Antiarrhythmic mechanisms of beta blocker therapy

Effect of Digoxin vs Beta-Blockers on Left Atrial Strain for Heart Rate-Controlled Atrial Fibrillation: The DIGOBET-AF Randomized Clinical Trial

BACKGROUND AND OBJECTIVE: Left atrial strain (LAS) has prognostic value in patients with atrial fibrillation (AF). Consequently, therapies that improve LAS may help reduce AF-related adverse cardiac events. We aimed to compare how digoxin and bisoprolol modulate LAS in patients with AF being treated with rate control.

METHODS

This was a bicentric randomized controlled trial. Patients with AF, naïve to beta-blockers and digoxin, and scheduled for treatment with a rate control strategy were randomized to receive oral bisoprolol 5-10 mg daily or digoxin 0.25 mg daily. The primary aim was to compare the change in peak LAS before and after 30 days of treatment between the two groups.

RESULTS

A total of 60 patients, equally distributed between the two groups, completed the trial. By day 30, there was no significant difference in global peak LAS between the groups. However, when analyzed separately, the two-chamber view showed a significantly higher peak LAS in the digoxin group than in the BB group (mean 7.5 ± standard deviation 3.2% vs. 5.9 ± 3.4%; p = 0.004). Similarly, the four-chamber view also showed a higher peak LAS in the digoxin group (7.2 ± 3.6% vs. 6.4 ± 3.8%; p = 0.047). Considering the entire LAS curve rather than solely the peak value, digoxin significantly increased all LAS curves. In the global and four-chamber view, the digoxin maximum effect occurred significantly earlier than the peak of the LAS curve (p < 0.001). This effect remained constant over the cardiac cycle in the two-chamber curve (p < 0.001).

CONCLUSION

Our findings suggest that, in patients with rate-controlled AF, digoxin positively modulates LAS when compared with bisoprolol.

CLINICAL TRIALS REGISTRATION NUMBER

NCT05540600, https://clinicaltrials.gov .

Effect of 24-hour heart rate fluctuations on mortality in patients with acute myocardial infarction: based on the MIMIC III database

BACKGROUND

Heart rate (HR) was one of the risk factors for cardiovascular disease, but there was insufficient evidence to demonstrate a relationship between heart rate fluctuations and the prognosis of patients with acute myocardial infarction (AMI). The objective of this study is to investigate the relationship between 24-h heart rate fluctuations after admission to the Intensive Care Unit (ICU) and 30-day, 1-year, and 3-year mortality rates in patients with AMI in order to examine its implications for prognosis in AMI patients.

METHODS

All data were obtained from the Medical Information Mart for Intensive Care III Database (MIMIC III). We calculated heart rate fluctuations using the maximum and minimum values of the patient's heart rate during the first 24 h after ICU admission and divided them into three groups (< 23beats/min, 23-33beats/min, > 33beats/min) according to tertiles. The COX risk regression model was applied to the analysis, and subgroup analyses were performed for use in testing the robustness of the results. Curve fitting was performed to explore whether there was a nonlinear relationship between heart rate fluctuations and mortality. Outcome measures were 30-day, 1-year, and 3-year mortality in patients with AMI.

RESULTS

After strict confounding adjustment, COX multifactorial analysis showed that patients' heart rate fluctuations were positively associated with 30-day, 1-year, and 3-year mortality rates (HR = 1.17, 95%CI: 1.11 ~ 1.23; HR = 1.17, 95%CI: 1.12 ~ 1.22; HR = 1.17, 95%CI: 1.12 ~ 1.21). In addition, the high heart rate fluctuation group (> 33 beats/min) had a significantly increased risk of death (HR = 1.76, 95%CI: 1.28 ~ 2.42; HR = 1.59, 95%CI: 1.25 ~ 2.03; HR = 1.43, 95%CI: 1.15 ~ 1.77). In the curve-fitting analysis, a J-shaped curve relationship among heart rate fluctuations and 1- and 3-year mortality was found (p for non-linearity = 0.049; p for non-linearity = 0.004), with an inflection point of 28 beats/min. In subgroup analyses, there was an interaction between heart rate fluctuations and age (P for interaction = 0.041).

CONCLUSIONS

Heart rate fluctuations within 24 h after ICU admission of AMI patients were associated with 30-day, 1-year, and 3-year mortality, which is a simple and stable predictor of patients' short- and long-term prognosis. Furthermore, 24-h heart rate fluctuations showed a "J" curve relationship with 1- and 3-year mortality, with fluctuations of 28 beats/min predicting the best prognosis.

A novel method for the measurement of cardiovascular responses to lower body negative pressure in the awake instrumented rat

Lower body negative pressure (LBNP) has been used for decades in humans to model arterial baroreceptor unloading and represents a powerful tool for evaluating cardiovascular responses to orthostatic challenges. However, LBNP studies in animals have been limited to conditions of anesthesia or sedation, where cardiovascular reflexes are altered. Given the consequent uncertainties, the usefulness of LBNP studies in these preclinical models has been severely hampered. Here, we developed an approach using a novel system to study LBNP responses in awake rats instrumented for telemetric blood pressure (BP) measurement. BP responses to progressive levels of LBNP (-3 to -15 mmHg) were first made in awake rats, followed by measurements under various treatments. In awake untreated rats, BP was well maintained up to -15 mmHg LBNP and there was a robust baroreceptor response in heart rate (HR). Under anesthesia with 3% isoflurane, BP was not maintained at LBNP below -3 mmHg and baroreceptor responses in HR were completely blocked, confirming the limited usefulness of this method under anesthesia. Interrogation of the autonomic pathways involved in the response revealed that muscarinic (atropine) and β1-adrenergic (atenolol) blockade, separately or together, blocked the HR responses, but BP remained well maintained. α1-adrenergic blockade (prazosin) severely blunted the ability to maintain BP in response to LBNP. These data are consistent with findings in human subjects in that the vascular component of the orthostatic reflex predominates in preserving BP. Validation of this novel method provides a valuable tool for investigating orthostatic (in)tolerance in a facile preclinical model.NEW & NOTEWORTHY Orthostatic hypotension or intolerance is a common but often underappreciated disorder that is associated with a variety of neurological comorbidities. LBNP studies provide a valuable tool to study these conditions, but heretofore could only be used in human subjects, since animal subjects needed to be anesthetized or sedated, which blunts or eliminates neurocardiovascular reflexes. This novel method allowing LBNP studies in awake rats will provide a valuable preclinical model for studying these disorders.

Exploration of the potential association between newer antiseizure medications and arrhythmias: Integrating pharmacovigilance and bioinformatics evidence

INTRODUCTION

Arrhythmias resulting from newer antiseizure medications (ASMs) may significantly impact the safety and quality of life of patients with epilepsy. This study investigated the potential association between new first-line or second-line ASMs and arrhythmias.

METHODS

Pharmacovigilance analysis was conducted using data from the Food and Drug Administration Adverse Event Reporting System (FAERS) from 2004 to 2023. A disproportionality analysis was performed to compare newer ASMs with other drugs, using carbamazepine and valproate as positive controls. Newer ASMs were categorized into sodium channel (SCN) main mechanism, SCN possible mechanism, and non-SCN group. The bioinformatics analysis involved retrieving therapeutic gene targets for ASMs from the DrugBank and OMIM databases, as well as identifying arrhythmia disease targets from the GeneCards database. Additionally, enrichment analysis of gene ontology functions and KEGG pathways was conducted.

RESULTS

A total of 3,457 cases of arrhythmias associated with newer ASMs were identified in the FAERS database. Disproportionality analysis indicates that brivaracetam (IC025 = 0.08), zonisamide (IC025 = 0.13), eslicarbazepine (IC025 = 0.39), and lacosamide (IC025 = 0.84) exhibited a positive signal for arrhythmias, with signals predominantly observed in the SCN main mechanism group. Furthermore, bioinformatics analysis revealed the involvement of adrenergic signaling in cardiac myocytes, as well as the participation of sodium channel genes in ASM-induced arrhythmias.

CONCLUSION

Our findings suggest a potential association between SCN-ASMs and arrhythmias, highlighting the importance of monitoring and evaluating the safety profiles of newer ASMs in clinical practice. Further research is necessary to elucidate the underlying mechanisms and inform patient care strategies.

Impact of Adherence to Beta-Blockers in Patients With All-Comers ST-Segment Elevation Myocardial Infarction and According to Left Ventricular Ejection Fraction at Discharge: Results From the Real-World Registry FAST-STEMI

ABSTRACT

Beta-blockers are a crucial part of post-myocardial infarction (MI) pharmacological therapy. Recent studies have raised questions about their efficacy in patients without reduced left ventricular ejection fraction (LVEF). This study aims to assess adherence to beta-blockers after discharge for ST-segment elevation myocardial infarction (STEMI) and the impact of adherence on outcomes based on LVEF at discharge. The retrospective registry FAST-STEMI evaluated real-world adherence to main cardiovascular drugs in patients with STEMI between 2012 and 2017 by comparing purchased tablets with expected ones at 1 year through pharmacy registries. Optimal adherence was defined as ≥80%. Primary outcomes included all-cause and cardiovascular death while secondary outcomes were MI, major/minor bleeding events, and ischemic stroke. The study included 4688 patients discharged on beta-blockers. The mean age was 64 ± 12.3 years, 76% were male, and the mean LVEF was 49.2 ± 8.8%. The mean adherence at 1 year was 87.1%. Optimal adherence was associated with lower all-cause (adjusted hazard ratio, 0.62, 95% confidence interval, 0.41-0.92, P : 0.02) and cardiovascular (adjusted hazards ratio, 0.55, 95% confidence interval, 0.26-0.98, P : 0.043) mortality. In patients with LVEF ≤40%, optimal adherence was linked to reduced all-cause and cardiovascular mortality, but this was not found in patients with either preserved or mildly reduced LVEF. Predictors of cardiovascular mortality included older age, chronic kidney disease, male gender, and atrial fibrillation. Optimal adherence to beta-blocker therapy in patients with all-comers STEMI reduced all-cause and cardiovascular mortality at 1 year; once stratified by LVEF, this effect was confirmed only in patients with reduced LVEF (<40%) at hospital discharge. Impact of adherence to beta-blockers in all-comers STEMI patients and according to LVEF at discharge: results from the real-world registry FAST-STEMI.

Effects of spatially dense adrenergic stimulation to rotor behaviour in simulated atrial sheets

Sympathetic hyperactivity via spatially dense adrenergic stimulation may create pro-arrhythmic substrates even without structural remodelling. However, the effect of sympathetic hyperactivity on arrhythmic activity, such as rotors, is unknown. Using simulations, we examined the effects of gradually increasing the spatial density of adrenergic stimulation (AS) in atrial sheets on rotors. We compared their characteristics against rotors hosted in atrial sheets with increasing spatial density of minimally conductive (MC) elements to simulate structural remodelling due to injury or disease. We generated rotors using an S1-S2 stimulation protocol. Then, we created phase maps to identify phase singularities and map their trajectory over time. We measured each rotor's duration (s), angular speed (rad/s), and spatiotemporal organization. We demonstrated that atrial sheets with increased AS spatial densities could maintain rotors longer than with MC elements (2.6 ± 0.1 s vs. 1.5 ± 0.2 s, p<0.001). Moreover, rotors have higher angular speed (70 ± 7 rads/s vs. 60 ± 15 rads/s, p<0.05) and better spatiotemporal organization (0.56 ± 0.05 vs. 0.58 ± 0.18, p<0.05) in atrial sheets with less than 25% AS elements compared to MC elements. Our findings may help elucidate electrophysiological potential alterations in atrial substrates due to sympathetic hyperactivity, particularly among individuals with autonomic derangements caused by chronic distress.

Scar-Related Ventricular Tachycardia: Pathophysiology, Diagnosis, and Management

Scar-related ventricular tachycardia (VT) commonly results from scarring in the myocardium, principally produced by antecedent myocardial infarction, cardiomyopathy, or prior cardiac surgery. The resultant arrhythmogenic substrate from scarred tissue and the alteration of normal cardiac electrical conduction predispose patients to reentrant circuits, followed by VT. This literature review synthesizes current research on pathophysiology, diagnostic methods, and treatment modalities of scar-related VT. The primary contents of the review are descriptions of the mechanisms through which myocardial fibrosis results in VT, clinical presentations of the condition, and advanced diagnostic techniques, including electrophysiological studies and mapping. Furthermore, the review outlines the various management strategies, such as implantable cardioverter-defibrillators, catheter ablation, stereotactic arrhythmia radioablation, and surgical ablation. The discussion also includes emerging therapeutics, such as gene therapy, artificial intelligence, and precision medicine in managing scar-related VT, emphasizing the ongoing advancements aimed at improving patient outcomes.

Efficacy of prescribing Inderal for polymorphic ventricular tachycardia in a young patient with the normal QT interval: A case report study

Polymorphic ventricular tachycardia (PVT) is a group of life-threatening heart rhythm disorders. These arrhythmias share similar electrocardiographic characteristics but require different modes of therapy for effective treatment. It is important to note that the medications that are considered the first-line treatment for one type of PVT may not be appropriate for another type, and may worsen the condition. Therefore, it is crucial to accurately diagnose the type of PVT before initiating treatment to provide the most effective therapy for the patient. A 42-year-old man was admitted to the emergency department with dyspnea, Levine sign, and severe chest pain. His electrocardiogram showed ST elevation, and the QT interval was normal. The patient was sent to the cath lab based on the treatment protocols. According to the results of angiography, three coronary arteries were severely obstructed. His coronary arteries did not open during percutaneous coronary intervention; thus, the healthcare team decided on open heart surgery. He suffered from recurrent PVT following open heart surgery and did not respond to any of the drugs suitable for this type of tachycardia. Inderal prevented the recurrence of ventricular tachycardia (VT) in a patient with polymorphic VT without QT prolongation, contrary to the healthcare team's expectations. Inderal was used as the last line of treatment because this patient's arrhythmia was polymorphic VT without QT prolongation. Inderal is typically used for treating VT in patients with long QT syndromes and heart structural disorders. This case report aims to highlight the impact of Inderal on polymorphic tachycardia, specifically in cases where the QT interval is not elongated. In this particular case, the standard treatment approaches were ineffective in preventing reversibility, but Inderal proved to be successful. Therefore, we feel it is important to document and share this case.

Understanding Arrhythmia-Induced Cardiomyopathy: Symptoms and Treatments

Arrhythmia-induced cardiomyopathy is a complex condition that causes a decline in heart function as a result of irregular heart rhythms. This disorder highlights the link between irregular heart rhythm and heart failure, necessitating prompt identification and intervention. It often occurs due to ongoing fast heart rhythms like atrial fibrillation or tachycardia. Understanding the mechanisms, symptoms, and available treatments is essential for enhancing patient outcomes given the complicated nature of the condition. This article delves into various aspects of arrhythmia-induced cardiomyopathy, including pathogenesis, clinical presentation, diagnostic methods, epidemiology, typical arrhythmias associated with the condition, and management options. It assesses patients' future outlook and necessary follow-up, aiming to provide healthcare providers with a comprehensive understanding of how to handle this intricate condition. The article emphasizes the important effect an integrative approach can have on both patients' lives and the clinical consequences of diagnosing and treating this condition. This extensive understanding enhances the resources at the disposal of physicians, enabling targeted treatments that enhance cardiomyopathy by targeting arrhythmia regulation. More research and development are needed in the field of cardiomyopathy and arrhythmia relationship. The presentation urges the medical field to delve deeper into the complexities of illness by emphasizing the need for continuous research and a multifaceted treatment plan. By combining these understandings, our goal is to enhance patient outcomes and create opportunities for further studies on cardiovascular wellness.

Atrial Arrhythmia and Bradycardia as a Presentation of Congenital Long QT Syndrome

We present a term newborn with atrial arrhythmia on the first day of life (DOL). An echocardiogram showed normal structure and normal function; laboratory testing showed normal electrolytes and thyroid function. After initiation of flecainide, the EKG on DOL 2 showed significant and increasing bradycardia with atrial arrhythmia and extremely prolonged QTc interval. Flecainide was stopped and esmolol started. After 6 h of treatment, atrial tachycardia was suppressed, and the rhythm converted to sinus. Genetic testing found variants of unknown significance in the ALPK3 gene and KCNQ1 gene, which has been associated with long QT syndrome (LQTs). LQTs in infants can present as bradycardia, 2:1 AV block, or torsades de pointes. Our review of the literature found only one other case report of atrial arrhythmia in a newborn with congenital LQTs. Diagnosis of LQTs via EKG alone is difficult in neonates since the ST segment and T wave on the first DOL are usually flattened, making correct measurement of the QTc interval difficult. β-blockers, the first line of treatment for LQTs, are known to shorten QTc intervals and prevent arrhythmia events. As in our patient, β-blockers may be helpful for atrial arrhythmia prevention in patients with adrenergically mediated atrial tachycardia. In conclusion, atrial arrhythmia with bradycardia can be a presentation of congenital LQTs and be difficult to recognize. For neonates with this presentation with no evidence of myocarditis, congenital heart disease, or significant respiratory illness, genetic congenital LQTs should be highly suspected, especially when associated with low resting heart rates.

The Danish-Norwegian randomized trial on beta-blocker therapy after myocardial infarction: Design, rationale, and baseline characteristics

BACKGROUND AND AIMS

The evidence for beta-blocker therapy after myocardial infarction (MI) is randomized trials conducted more than 30 years ago, and the continued efficacy has been questioned.

DESIGN AND METHODS

The ongoing Danish (DANBLOCK) and Norwegian (BETAMI) randomized beta-blocker trials are joined to evaluate the effectiveness and risks of long-term beta-blocker therapy after MI. Patients with normal or mildly reduced left ventricular ejection fraction (LVEF ≥ 40%) will be randomized to open-label treatment with beta-blockers or no such therapy. The event-driven trial will randomize ∼5700 patients and continue until 950 primary endpoints have occurred. As of July 2023, 5228 patients have been randomized. Of the first 4000 patients randomized, median age was 62 years, 79% were men, 48% had a ST-segment elevation myocardial infarction (STEMI), and 84% had a normal LVEF. The primary endpoint is a composite of adjudicated recurrent MI, incident heart failure (HF), coronary revascularization, ischaemic stroke, all-cause mortality, malignant ventricular arrhythmia, or resuscitated cardiac arrest. The primary safety endpoint includes a composite of recurrent MI, HF, all-cause mortality, malignant ventricular arrhythmia, or resuscitated cardiac arrest 30 days after randomization. Secondary endpoints include each of the components of the primary endpoint, patient-reported outcomes, and other clinical outcomes linked to beta-blocker therapy. The primary analysis will be conducted according to the intention-to-treat principle using a Cox proportional hazards regression model. End of follow-up is expected in December 2024.

CONCLUSION

The combined BETAMI-DANBLOCK trial will have the potential to affect current clinical practice for beta-blocker therapy in patients with normal or mildly reduced LVEF after MI.

An Overview of the Pharmacokinetics and Pharmacodynamics of Landiolol (an Ultra-Short Acting β1 Selective Antagonist) in Atrial Fibrillation

Landiolol is an ultra-short-acting, selective β1-adrenergic receptor blocker that was originally approved in Japan for the treatment of intraoperative tachyarrhythmias. It has gained attention for its use in the management of tachyarrhythmias and perioperative tachycardia, especially atrial fibrillation for both cardiac and non-cardiac surgeries. It can be the ideal agent for heart rate control due to its high β1-selectivity, potent negative chronotropic effect, a limited negative inotropic potential, and an ultrashort elimination half-life (around 4 min); moreover, it may have a potential therapeutic effects for sepsis and pediatric patients. Landiolol seems to be superior to other short-acting and selective beta-blockers such as esmolol. This review aims to provide a comprehensive overview of landiolol, a new ultra-short-acting β1 selective antagonist, including its pharmacology, clinical applications, efficacy, safety profile, and future directions in research and clinical data.

Anti-Arrhythmic Effects of Heart Failure Guideline-Directed Medical Therapy and Their Role in the Prevention of Sudden Cardiac Death: From Beta-Blockers to Sodium-Glucose Cotransporter 2 Inhibitors and Beyond

Sudden cardiac death (SCD) accounts for a substantial proportion of mortality in heart failure with reduced ejection fraction (HFrEF), frequently triggered by ventricular arrhythmias (VA). This review aims to analyze the pathophysiological mechanisms underlying VA and SCD in HFrEF and evaluate the effectiveness of guideline-directed medical therapy (GDMT) in reducing SCD. Beta-blockers, angiotensin receptor-neprilysin inhibitors, and mineralocorticoid receptor antagonists have shown significant efficacy in reducing SCD risk. While angiotensin-converting enzyme inhibitors and angiotensin receptor blockers exert beneficial impacts on the renin-angiotensin-aldosterone system, their direct role in SCD prevention remains less clear. Emerging treatments like sodium-glucose cotransporter 2 inhibitors show promise but necessitate further research for conclusive evidence. The favorable outcomes of those molecules on VA are notably attributable to sympathetic nervous system modulation, structural remodeling attenuation, and ion channel stabilization. A multidimensional pharmacological approach targeting those pathophysiological mechanisms offers a complete and synergy approach to reducing SCD risk, thereby highlighting the importance of optimizing GDMT for HFrEF. The current landscape of HFrEF pharmacotherapy is evolving, with ongoing research needed to clarify the full extent of the anti-arrhythmic benefits offered by both existing and new treatments.

Ivabradine could not decrease mitral regurgitation triggered atrial fibrosis and fibrillation compared with carvedilol

BACKGROUND

Ivabradine, a medical treatment for heart failure (HF), reduces heart rate (HR) and prolongs diastolic perfusion time. It is frequently prescribed to patients with HF who have a suboptimal response or intolerance to beta-blockers. Degenerative mitral regurgitation (MR) is a valvular heart disease often associated with the development of HF and atrial fibrillation (AF). However, studies comparing the effects of ivabradine and beta-blockers on MR are lacking. Therefore, this study aimed to explore the potential therapeutic effects of ivabradine and carvedilol on MR using a rat model.

METHODS AND RESULTS

Using a novel echo-guided mini-invasive surgery, MR was created in 12-weeks-old Sprague-Dawley rats. After 2 weeks, the rats were randomized to receive either ivabradine or carvedilol for 4 weeks. Echocardiography was performed at baseline and at two-week intervals. Following haemodynamic studies, postmortem tissues were analysed. Notably, the MR-induced myocardial dysfunction did not improve considerably after treatment with ivabradine or carvedilol. However, in haemodynamic studies, pharmacological therapies, particularly carvedilol, mitigated MR-induced chamber dilatation (end-systolic volume and end-diastolic volume; MR vs. MR + Carvedilol; P < 0.05) and decreased compliance (end-systolic pressure-volume relationship; MR vs. MR + Carvedilol; P < 0.05). Compared with ivabradine, a shorter duration (MR vs. MR + Carvedilol; P < 0.05) and reduced inducibility (MR vs. MR + Carvedilol and MR vs. MR + Ivabradine; P < 0.05) of AF were observed in MR rats treated with carvedilol. Similarly, reduced cardiac fibrosis and apoptosis were observed in the MR rat model in the treatment groups, especially in those treated with carvedilol (MR vs. MR + Carvedilol; P < 0.01).

CONCLUSIONS

Although both ivabradine and carvedilol, at least in part, mitigated MR-induced chamber dilatation and decreased compliance, carvedilol had a better effect on reversing MR-induced cardiac fibrosis, apoptosis, and arrhythmogenesis than ivabradine. When compared with Ivabradine, MR rats treated with carvedilol exhibited a shorter duration and reduced inducibility of AF, thus providing more effective suppression of HCN4. Further investigations are required to validate our findings.

Beta-blockers in Hypertensive Left Ventricular Hypertrophy and Atrial Fibrillation Prevention

BACKGROUND

Hypertensive left ventricular hypertrophy (HTN LVH) is a key risk factor for atrial fibrillation (AF).

OBJECTIVE

To evaluate the possible role of beta-blockers (BBs) in addition to a renin-angiotensinaldosterone system (RAAS) blocker in AF prevention in patients with HTN LVH.

METHODS

We performed a PubMed, Elsevier, SAGE, Oxford, and Google Scholar search with the search items 'beta blocker hypertension left ventricular hypertrophy patient' from 2013-2023. In the end, a 'snowball search', based on the references of relevant papers as well as from papers that cited them was performed.

RESULTS

HTN LVH is a risk factor for AF. In turn, AF substantially complicates HTN LVH and contributes to the genesis of heart failure (HF) with preserved ejection fraction (HFpEF). The prognosis of HFpEF is comparable with that of HF with reduced EF (HFrEF), and, regardless of the type, HF is associated with five-year mortality of 50-75%. The antiarrhythmic properties of BBs are wellrecognized, and BBs as a class of drugs are - in general - recommended to decrease the incidence of AF in HTN.

CONCLUSION

BBs are recommended (as a class) for AF prevention in several contemporary guidelines for HTN. LVH regression in HTN - used as a single criterion for the choice of antihypertensive medication - does not capture this protective effect. Consequently, it is worth studying how meaningful this antiarrhythmic action (to prevent AF) of BBs is in patients with HTN LVH in addition to a RAAS blocker.

Computational Modeling of Cardiac Electrophysiology

Mathematical modeling and simulation are well-established and powerful tools to integrate experimental data of individual components of cardiac electrophysiology, excitation-contraction coupling, and regulatory signaling pathways, to gain quantitative and mechanistic insight into pathophysiological processes and guide therapeutic strategies. Here, we briefly describe the processes governing cardiac myocyte electrophysiology and Ca2+ handling and their regulation, as well as action potential propagation in tissue. We discuss the models and methods used to describe these phenomena, including procedures for model parameterization and validation, in addition to protocols for model interrogation and analysis and techniques that account for phenotypic variability and parameter uncertainty. Our objective is to provide a summary of basic concepts and approaches as a resource for scientists training in this discipline and for all researchers aiming to gain an understanding of cardiac modeling studies.

Beyond β-Blockade: ACE Inhibitors Reduce Non-Cardiac Mortality in High Killip Grade AMI Patients

OBJECTIVE

This study evaluates the 3-year clinical outcomes of high Killip grade (III/IV) acute myocardial infarction (AMI) patients treated with either β-blockers (BB) and angiotensin-converting enzyme inhibitors (ACEI) or BB and angiotensin receptor blockers (ARB).

METHODS

A total of 13,105 patients were registered at the Korea Acute Myocardial Infarction Registry at the National Institute of Health (KAMIR-NIH). Among them, 871 patients with high Killip classification AMI were divided into the BB + ACEI group (n = 489) and the BB + ARB group (n = 381). Following propensity score matching, 343 patients were selected in each group. All patients completed a 3-year follow-up period.

RESULTS

The results indicate no significant differences between the BB + ACEI group and BB + ARB group in terms of cardiac death, recurrent myocardial infarction, and the rate of repeat percutaneous coronary intervention. However, the BB + ACEI group exhibited significantly lower risks in major adverse cardiac events (HR = 0.574, 95% CI: 0.421-0.783, p < .001), all-cause mortality (HR = 0.561, 95% CI: 0.404-0.778, p = .001), and non-cardiac death (HR = 0.365, 95% CI: 0.208-0.639, p < .001) compared to the BB + ARB group.

CONCLUSION

Our results suggest that BB + ACEI treatment is more beneficial than BB + ARB for high Killip grade AMI patients. Additionally, the BB + ACEI group has a superior preventative effect on mortality compared to the BB + ARB group.

Assessment of Plasma Exovesicles and Prothrombotic Biomarkers Suggest Prethrombotic Conditions in Chagas Cardiomyopathy in Colombia

Chagas cardiomyopathy (CCC) is associated with coagulation disorders that frequently culminate in thrombotic events, contributing to increased mortality rates in this clinical condition. Considering the demonstrated effect that extracellular vesicles (EVs) have on regulating inflammatory processes, coagulation, and angiogenesis, the present study aims to characterize plasma EVs and their relationship with coagulation disorders in patients with CCC. A total of 78 patients were assessed with 46.1% (36/78) representing the CCC group, 8.9% (7/78) with cardiomyopathy unrelated to Chagas disease (CM group), and 44.8% (35/78) comprising the control group, which included individuals without cardiomyopathy and negative for T. cruzi infection. Plasma EVs concentration (EVs/mL) for each individual was evaluated by flow cytometry, along with the proportion of EVs expressing PSGL-1 (PSGL-1+ EVs), Tissue Factor (TF + EVs), and CD41a (CD41a + EVs). The ability of EVs to induce platelet aggregation was evaluated by spectrophotometry. We also evaluated other prothrombotic biomarkers, including platelet count, activated partial thromboplastin time (PTT), prothrombin time (PT), and D-dimer levels. The results revealed elevated D-dimer levels in the CCC group, accompanied by a decrease in the count of EVs per mL of plasma and a significant increase in the proportion of PSGL-1+ EVs (P < .05) compared to the control group. Other parameters did not exhibit significant differences between groups. The elevated levels of PSGL-1+ EVs in the CCC group may be attributed to myocardial inflammatory processes, which, upon interaction with platelet-derived P-selectin, could promote thrombus formation, as indicated by the increased D-dimer levels in this group.

New-Onset Sleep Disorders before Cardiac Surgery May Indicate an Increased Risk of Postoperative Atrial Fibrillation

PURPOSE

We aimed to determine if sleep disorders before cardiac surgery indicate an increased risk of postoperative atrial fibrillation (POAF).

METHODS

In this study, 238 patients undergoing coronary artery bypass grafting in our center were included. Patients were separated into the preoperative sleep disorder group and the control group. The primary endpoint was the incidence of POAF, and the secondary endpoints were the incidence of postoperative stroke, duration of invasive ventilation, length of intensive care unit, and hospitalization stay. Propensity score matching and multivariable logistic regression were used for adjusting potential confounders.

RESULTS

A total of 165 (69.3%) patients had sleep disorders before surgery, and 73 well-matched pairs were generated. A higher incidence of POAF was found in the preoperative sleep disorder group (16.4% versus 5.5%, p = 0.034). In multivariable logistic regression, preoperative sleep disorders were correlated to a higher risk of POAF (odds ratio = 4.627, 95% confidence interval: 1.181-18.123, p = 0.028). In the subgroup of patients without long-term sleep disorders, those who experienced preoperative sleep disorders had a higher incidence of POAF (16.1% versus 4.3%, p = 0.024), meanwhile, no difference was found in the subgroup of long-term sleep disorders.

CONCLUSION

New-onset sleep disorders before cardiac surgery may indicate a higher incidence of POAF.

Further exploration of the collision-induced dissociation of select beta blockers: Acebutolol, atenolol, bisoprolol, carteolol, and labetalol

Beta blockers are a class of drugs commonly used to treat heart-related diseases; they are also regulated under the World Anti-Doping Agency. Tandem mass spectrometry is often used in the pharmaceutical industry, clinical analysis laboratory, and antidoping laboratory for detection and characterization of drugs and their metabolites. A deeper chemical understanding of dissociation pathways may eventually lead to an improved ability to predict tandem mass spectra of compounds based strictly on their chemical structure (or vice versa), which is especially important for characterization of unknowns such as emerging designer drugs or novel metabolites. In addition to providing insights into dissociation pathways, the use of energy-resolved breakdown curves can produce improved selectivity and lend insights into optimal fragmentation conditions for liquid chromatography-tandem mass spectrometry LC-MS/MS workflows. Here, we perform energy-resolved collision cell and multistage ion trap collision-induced dissociation-mass spectrometry (CID-MS) experiments, along with complementary density functional theory calculations, on five beta blockers (acebutolol, atenolol, bisoprolol, carteolol, and labetalol), to better understand the details of the pathways giving rise to the observed MS/MS patterns. Results from this work are contextualized within previously reported literature on these compounds. New insights into the formation of the characteristic product ion m/z 116 and the pathway leading to characteristic loss of 77 u are highlighted. We also present comparisons of breakdown curves obtained via qToF, quadrupole ion trap, and in-source CID, allowing for differences between the data to be noted and providing a step toward allowing for improved selectivity of breakdown curves to be realized on simple instruments such as single quadrupoles or ion traps.

The long-term health outcomes, pathophysiological mechanisms and multidisciplinary management of long COVID

There have been hundreds of millions of cases of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the growing population of recovered patients, it is crucial to understand the long-term consequences of the disease and management strategies. Although COVID-19 was initially considered an acute respiratory illness, recent evidence suggests that manifestations including but not limited to those of the cardiovascular, respiratory, neuropsychiatric, gastrointestinal, reproductive, and musculoskeletal systems may persist long after the acute phase. These persistent manifestations, also referred to as long COVID, could impact all patients with COVID-19 across the full spectrum of illness severity. Herein, we comprehensively review the current literature on long COVID, highlighting its epidemiological understanding, the impact of vaccinations, organ-specific sequelae, pathophysiological mechanisms, and multidisciplinary management strategies. In addition, the impact of psychological and psychosomatic factors is also underscored. Despite these crucial findings on long COVID, the current diagnostic and therapeutic strategies based on previous experience and pilot studies remain inadequate, and well-designed clinical trials should be prioritized to validate existing hypotheses. Thus, we propose the primary challenges concerning biological knowledge gaps and efficient remedies as well as discuss the corresponding recommendations.

Integrative human atrial modelling unravels interactive protein kinase A and Ca2+/calmodulin-dependent protein kinase II signalling as key determinants of atrial arrhythmogenesis

AIMS

Atrial fibrillation (AF), the most prevalent clinical arrhythmia, is associated with atrial remodelling manifesting as acute and chronic alterations in expression, function, and regulation of atrial electrophysiological and Ca2+-handling processes. These AF-induced modifications crosstalk and propagate across spatial scales creating a complex pathophysiological network, which renders AF resistant to existing pharmacotherapies that predominantly target transmembrane ion channels. Developing innovative therapeutic strategies requires a systems approach to disentangle quantitatively the pro-arrhythmic contributions of individual AF-induced alterations.

METHODS AND RESULTS

Here, we built a novel computational framework for simulating electrophysiology and Ca2+-handling in human atrial cardiomyocytes and tissues, and their regulation by key upstream signalling pathways [i.e. protein kinase A (PKA), and Ca2+/calmodulin-dependent protein kinase II (CaMKII)] involved in AF-pathogenesis. Populations of atrial cardiomyocyte models were constructed to determine the influence of subcellular ionic processes, signalling components, and regulatory networks on atrial arrhythmogenesis. Our results reveal a novel synergistic crosstalk between PKA and CaMKII that promotes atrial cardiomyocyte electrical instability and arrhythmogenic triggered activity. Simulations of heterogeneous tissue demonstrate that this cellular triggered activity is further amplified by CaMKII- and PKA-dependent alterations of tissue properties, further exacerbating atrial arrhythmogenesis.

CONCLUSIONS

Our analysis reveals potential mechanisms by which the stress-associated adaptive changes turn into maladaptive pro-arrhythmic triggers at the cellular and tissue levels and identifies potential anti-AF targets. Collectively, our integrative approach is powerful and instrumental to assemble and reconcile existing knowledge into a systems network for identifying novel anti-AF targets and innovative approaches moving beyond the traditional ion channel-based strategy.

Impact of beta-blockers on mortality and cardiovascular disease outcomes in patients with obstructive sleep apnoea: a population-based cohort study in target trial emulation framework

Background

There is no real-world evidence regarding the association between beta-blocker use and mortality or cardiovascular outcomes in patients with obstructive sleep apnoea (OSA). We aimed to investigate the impact of beta-blocker use on all-cause mortality and cardiovascular diseases (CVDs) in patients with OSA.

Methods

We conducted a target trial emulation study of 37,581 patients with newly diagnosed OSA from 1st January 2000 to 30th November 2021 using the IMRD-UK database (formerly known as the THIN database). We compared the treatment strategies of initiating beta-blocker treatment within one year versus non-beta-blocker treatment through the method of clone-censor-weight. Covariates, including patients' demographics, lifestyle, comorbidities, and recent medications, were measured and controlled. Patients were followed up for all-cause mortality or composite CVD outcomes (angina, myocardial infarction, stroke/transient ischaemic attack, heart failure, or atrial fibrillation). We estimated the five-year absolute risks, risk differences and risk ratio with 95% confidence intervals (CIs) with standardised, weighted pooled logistic regression, which is a discrete-time hazard model for survival analysis. Several sensitivity analyses were performed, including multiple imputation addressing the missing data.

Findings

The median follow-up time was 4.1 (interquartile range, 1.9-7.8) years. The five-year absolute risk of all-cause mortality and CVD outcomes were 4.9% (95% CI, 3.8-6.0) and 13.0% (95% CI, 11.4-15.0) among beta-blocker users, and 4.0% (95% CI, 3.8-4.2) and 9.4% (95% CI, 9.1-9.7) among non-beta-blocker users, respectively. The five-year absolute risk difference and risk ratio between the two groups for all-cause mortality and CVD outcomes were 0.9% (95% CI, -0.2 to 2.1) and 1.22 (95% CI, 0.96-1.54), and 3.5% (95% CI, 2.1-5.5) and 1.37 (95% CI, 1.22-1.62), respectively. Findings were consistent across the sensitivity analyses.

Interpretation

Beta-blocker treatment was associated with an increased risk of CVD and a trend for an increased risk of mortality among patients with OSA. Further studies are needed to confirm our findings.

Funding

Innovation and Technology Commission of the Hong Kong Special Administration Region Government.

Beta-Blockers and Their Current Role in Maternal and Neonatal Health: A Narrative Review of the Literature

Beta-blockers are a class of medications that act on beta-adrenergic receptors and are categorized as cardio-selective and non-selective. They are principally used to treat cardiovascular conditions such as hypertension and arrhythmias. Beta-blockers have also been used to treat non-cardiogenic indications in non-pregnant individuals and the pediatric population. In pregnancy, labetalol is the mainstay treatment for hypertension and other cardiovascular indications. However, contraindications to certain sub-types of beta-blockers include bradycardia, heart failure, obstructive lung diseases, and hemodynamic instability. There is conflicting evidence of the adverse effects on fetal and neonatal health due to a scarce safety and efficacy profile, and further studies are necessary to understand the pharmacokinetics of the different classes of beta-blockers in pregnancy and fetal health. Understanding the hemodynamic changes during the stages of pregnancy is important to target a more beneficial therapy for both mother and fetus as well as better neonatal outcomes. Beta-blocker use in the pediatric population is less documented in studies but does have the potential to treat various cardiogenic and non-cardiogenic conditions. Future comprehensive studies would further benefit the direction of beta-blocker treatment during pregnancy in neonates and pediatrics.

Overview of Cardiac Arrhythmias and Treatment Strategies

Maintenance of normal cardiac rhythm requires coordinated activity of ion channels and transporters that allow well-ordered propagation of electrical impulses across the myocardium. Disruptions in this orderly process provoke cardiac arrhythmias that may be lethal in some patients. Risk of common acquired arrhythmias is increased markedly when structural heart disease caused by myocardial infarction (due to fibrotic scar formation) or left ventricular dysfunction is present. Genetic polymorphisms influence structure or excitability of the myocardial substrate, which increases vulnerability or risk of arrhythmias in patients. Similarly, genetic polymorphisms of drug-metabolizing enzymes give rise to distinct subgroups within the population that affect specific drug biotransformation reactions. Nonetheless, identification of triggers involved in initiation or maintenance of cardiac arrhythmias remains a major challenge. Herein, we provide an overview of knowledge regarding physiopathology of inherited and acquired cardiac arrhythmias along with a summary of treatments (pharmacologic or non-pharmacologic) used to limit their effect on morbidity and potential mortality. Improved understanding of molecular and cellular aspects of arrhythmogenesis and more epidemiologic studies (for a more accurate portrait of incidence and prevalence) are crucial for development of novel treatments and for management of cardiac arrhythmias and their consequences in patients, as their incidence is increasing worldwide.

Comparing the Efficacy of Carvedilol and Flecainide on the Treatment of Idiopathic Premature Ventricular Complexes from Ventricular Outflow Tract: A Multicenter, Randomized, Open-Label Pilot Study

The mechanism of premature ventricular complexes (PVC) occurring in the ventricular outflow tract (OT) is related to an intracellular calcium overload and delayed afterdepolarizations that lead to triggered activity. The guidelines recommend using beta-blockers and flecainide for idiopathic PVCs, but they also acknowledge the limited evidence supporting this recommendation. We conducted a multicenter, randomized, open-label pilot study comparing the effect of carvedilol and flecainide on OT PVC, which are widely used to treat this arrhythmia. Patients with a 24 h Holter recording a PVC burden ≥ 5%, which showed positive R waves in leads II, III, and aVF, and without structural heart disease were enrolled. They were randomly assigned to the carvedilol or flecainide group, and the maximum tolerated dose was administered for 12 weeks. A total of 103 participants completed the protocol: 51 with carvedilol and 52 with flecainide. After 12 weeks of treatment, the mean PVC burden significantly decreased in both groups: 20.3 ± 11.5 to 14.6 ± 10.8% with carvedilol (p < 0.0001) and 17.1 ± 9.9 to 6.6 ± 9.9% with flecainide (p < 0.0001). Both carvedilol and flecainide effectively suppressed OT PVCs in patients without structural heart disease, with flecainide showing a superior efficacy compared to carvedilol.

Defining the Sarcomeric Proteoform Landscape in Ischemic Cardiomyopathy by Top-Down Proteomics

Ischemic cardiomyopathy (ICM) is a prominent form of heart failure, but the molecular mechanisms underlying ICM remain relatively understudied due to marked phenotypic heterogeneity. Alterations in post-translational modifications (PTMs) and isoform switches in sarcomeric proteins play important roles in cardiac pathophysiology. Thus, it is essential to define sarcomeric proteoform landscape to better understand ICM. Herein, we have implemented a top-down liquid chromatography (LC)-mass spectrometry (MS)-based proteomics method for the identification and quantification of sarcomeric proteoforms in the myocardia of donors without heart diseases (n = 16) compared to end-stage ICM patients (n = 16). Importantly, quantification of post-translational modifications (PTMs) and expression reveal significant changes in various sarcomeric proteins extracted from ICM tissues. Changes include altered phosphorylation and expression of cardiac troponin I (cTnI) and enigma homologue 2 (ENH2) as well as an increase in muscle LIM protein (MLP) and calsarcin-1 (Cal-1) phosphorylation in ICM hearts. Our results imply that the contractile apparatus of the sarcomere is severely dysregulated during ICM. Thus, this is the first study to uncover significant molecular changes to multiple sarcomeric proteins in the LV myocardia of the end-stage ICM patients using liquid chromatography-mass spectrometry (LC-MS)-based top-down proteomics. Raw data are available via the PRIDE repository with identifier PXD038066.

Tachy-Brady Syndrome in a Schizophrenic Patient: A Case Report

Tachy-brady syndrome is the result of sinus node dysfunction (SND), an electrocardiographic phenomenon caused by defective pacemaker functioning that leads to alternating arrhythmias. We present a case of a 73-year-old male with multiple mental health and medical comorbidities who was admitted to the inpatient floor for catatonia, paranoid delusions, refusal to eat, inability to cooperate with activities of daily life, and generalized weakness. Upon admission, a 12-lead electrocardiogram (ECG) showed an episode of atrial fibrillation with a ventricular rate of 64 beats per minute (bpm). During hospitalization, telemetry recorded a variety of arrhythmias such as ventricular bigeminy, atrial fibrillation, supraventricular tachycardia (SVT), multifocal atrial contractions, and sinus bradycardia. Each episode spontaneously reverted and the patient remained asymptomatic throughout these arrhythmic changes. These frequently fluctuating arrhythmias on resting ECG confirmed the diagnosis of tachycardia-bradycardia syndrome, also known as tachy-brady syndrome. Medical intervention, especially for cardiac arrhythmias, in patients with paranoid and catatonic schizophrenia can be challenging, as they might not share their symptoms. Additionally, certain psychotropic medications can also cause cardiac arrhythmias and must be carefully evaluated. The decision was made to start the patient on a beta-blocker and direct oral anticoagulation for reducing the risk of thromboembolic events. Due to an unsatisfactory response to drug therapy alone, the patient qualified as a candidate for definitive treatment with an implantable dual-chamber pacemaker. Our patient had a dual-chamber pacemaker implanted to prevent bradyarrhythmias and continued oral beta-blockers to prevent tachyarrhythmias.

Beta-blockers in cardiac arrhythmias-Clinical pharmacologist's point of view

β-blockers is a vast group of antiarrhythmic drugs which differ in their pharmacokinetic and chemical properties. Some of them block β-adrenergic receptors selectively while the others work non-selectively. Consequently, they reduce the influence of the sympathetic nervous system on the heart, acting negatively inotropic, chronotropic, bathmotropic and dromotropic. Although they have been present in medicine since the beginning of the 1960s, they still play a crucial role in the treatment of cardiac arrhythmias. They are also first-line group of drugs used to control the ventricular rate in patients with the most common arrhythmia-atrial fibrillation. Previous reports indicate that infection with SARS-CoV-2 virus may constitute an additional risk factor for arrhythmia. Due to the aging of the population in developed countries and the increase in the number of patients with cardiac burden, the number of people suffering from cardiac arrhythmias will increase in the upcoming years. As a result the role of above-mentioned beta-blockers will remain significant. Particularly noteworthy is propranolol-the oldest beta adrenergic antagonist, which in recent years has found additional applications due to its unique properties. In this article, we reviewed the accessible literature and summarized the current guidelines on the use of beta-blockers in the treatment of cardiac arrhythmias.

Clinical characteristics and prognosis of patients with left ventricular thrombus in East China

Background

Left ventricular thrombus (LVT) is a serious complication in patients with left ventricular dysfunction. However, there is still a paucity of data on treatments and prognosis of patients with LVT. This study aims to evaluate the clinical characteristics of patients with LVT and to determine the impact of LVT on the incidence of major adverse cardiovascular events (MACEs) and all-cause mortality.

Methods

From January 2010 to January 2020, 237 patients diagnosed with LVT at The Second Affiliated Hospital Zhejiang University School of Medicine in East China were retrospectively included. Clinical characteristics, treatments, MACEs, and bleeding events [thrombolysis in myocardial infarction (TIMI) I and II] were collected. MACE is determined as the composite of all-cause mortality, ischemic stroke, acute myocardial infarction (MI), and acute peripheral artery emboli.

Results

The all-cause mortality rate was 28.3% (89.6% due to cardiovascular death), ischemic stroke 8.4%, MI 3%, peripheral artery emboli 1.7%, and bleeding events (TIMI I and II) 7.6% were found during a median follow-up of 736 days. Total LVT regression occurred in 152 patients (64.1%). Atrial fibrillation [hazard ratio (HR), 3.049; 95% confidence interval (95% CI) 1.264–7.355; p = 0.013], moderate and severe renal function injuries (HR, 2.097; 95% CI, 1.027–4.281; p = 0.042), and left ventricular ejection fraction (LVEF) ≤ 50% (HR, 2.243; 95% CI 1.090–4.615; p = 0.028) were independent risk factors for MACE, whereas the use of β-blocker (HR, 0.397; 95% CI 0.210–0.753; p = 0.005) was its protective factor. Age (HR, 1.021; 95% CI 1.002–1.040; p = 0.031), previous caronary artery bypass grafting (CABG; HR, 4.634; 95% CI 2.042–10.517; p < 0.001), LVEF ≤ 50% (HR, 3.714; 95% CI 1.664–8.290; p = 0.001), and large thrombus area (HR, 1.071; 95% CI 1.019–1.126; p = 0.007) were independent risk factors for increasing all-cause mortality, whereas the use of β-blocker (HR, 0.410; 95% CI 0.237–0.708; p = 0.001) was protective factor.

Conclusion

This study showed that atrial fibrillation, moderate and severe renal dysfunction, and LVEF ≤ 50% were independent risk factors for MACE; age, previous CABG, LVEF ≤ 50%, and large thrombus area were independent risk factors for all-cause mortality. It was found that the use of β-blockers could improve the prognosis of patient with LVT for the first time. It is recommended that clinicians could be more active in applying patient with LVT with anticoagulants.

Harm of circadian misalignment to the hearts of the adolescent wistar rats

PURPOSE

The purpose of this study was to observe the harm of circadian misalignment (CM), caused by an inverted photoperiod (IP), on the hearts of the adolescent Wistar rats, and to explore the mechanisms leading to harm.

METHODS

An IP was used to create a CM model. A total of 174 Wistar rats were randomly divided into circadian alignment (CA) and CM groups (87 rats per group). The different activity rhythms of the two groups of rats were adjusted through different light/dark cycles for 90 days. We recorded the rhythmic activity trajectory and sleep time of the rats. After 90 days of modeling, we performed various analyses (i.e., blood pressure, weight, cardiac ultrasound tests, serological tests, cardiac tissue immunofluorescence, immunohistochemistry, transmission electron microscopy on myocardial mitochondria, western blotting, and quantitative polymerase chain reactions).

RESULTS

(1) The IP protocol caused CM in rats. (2) CM rats showed significantly higher blood pressure during the day (resting phase). They also showed significantly higher serum levels of angiotensin II and epinephrine during the day compared to the CA rats. (3) CM caused up-regulation of gene expression of adrenergic receptors α1 (α1-AR) and β1 (β1-AR) and down-regulation of the glucocorticoid receptor (Gr) gene expression in rat hearts. It also caused downregulation of Bmal1 expression. In addition, the changes in Bmal1 and Per2 correlated with the changes in β1-AR and α1-AR. (4) CM had adverse effects on multiple molecular proteins of the heart. (5) CM increased the collagen fibers in the rat heart and increased the destruction of mitochondria. (6) Eventually, CM caused a decrease in the pumping function of the heart and decreased the coronary blood flow rate.

CONCLUSIONS

(1) CM significantly affected the cardiac structure and function in the adolescent rats through a variety of mechanisms. (2) CM can regulate the expression of myocardial clock genes, and it is likely to have an impact on the heart through this pathway.

Maternal beta-blocker dose and risk of small-for gestational-age in women with heart disease

INTRODUCTION

Beta-blockers are prescribed for many pregnant women with heart disease, but whether there is a dose-dependent effect on fetal growth remains to be examined. We aimed to investigate if antenatal beta-blocker use and dose were associated with delivering a small-for-gestational-age infant among women with heart disease.

MATERIAL AND METHODS

Our cohort included women with heart disease who delivered at Oslo University Hospital between 2006 and 2015. Maternal heart disease was classified into modified WHO risk scores. Women with beta-blocker treatment were dichotomized into whether they had been treated with a low or high dose based on clinical factors. We compared the risk of delivering a small-for-gestational-age infant in women exposed to high doses, low doses, or with no exposure to antenatal beta-blockers while adjusting for severity of maternal heart disease in logistic regression models.

RESULTS

Of a total of 540 pregnancies among women with heart disease, 163 (30.2%) were exposed to beta-blocker treatment. The majority were treated with metoprolol (86.5%). Almost twice as many babies in the beta-blocker group were small-for-gestational-age, compared with the non-exposed group (19.8 vs 9.5%, P < 0.001). Women using a high-dose beta-blocker had a five-fold increased risk of delivering a small-for-gestational-age infant compared with non-exposure (adjusted odds ratio [aOR] 4.89, 95% confidence interval [CI] 2.22-10.78, P < 0.001). Women using a low dose of beta-blocker had a two-fold increased risk of delivering a small-for-gestational-age infant; however, the confidence interval included the null (aOR 1.75, 95% CI 0.83-3.72, P = 0.143). Results when restricting the analyses to metoprolol showed the same pattern, but with attenuation of risks.

CONCLUSIONS

We found a five-fold increased risk of delivering a small-for-gestational-age infant in women with heart disease treated with a high dose of beta-blocker, and a two-fold increased risk among those treated with a low dose, showing an apparent dose-response relation. Close monitoring of fetal growth is warranted among women with heart disease treated with beta-blockers. As drug therapy in pregnancy concerns both mother and fetus, an optimum balance for both should be the goal.

Congenital Heart Disease: The State-of-the-Art on Its Pharmacological Therapeutics

Congenital heart disease is one of the most common causes of death derived from malformations. Historically, its treatment has depended on timely diagnosis and early pharmacological and surgical interventions. Survival rates for patients with this disease have increased, primarily due to advancements in therapeutic choices, but mortality remains high. Since this disease is a time-sensitive pathology, pharmacological interventions are needed to improve clinical outcomes. Therefore, we analyzed the applications, dosage, and side effects of drugs currently used for treating congenital heart disease. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and potassium-sparing diuretics have shown a mortality benefit in most patients. Other therapies, such as endothelin receptor antagonists, phosphodiesterase-5 inhibitors, prostaglandins, and soluble guanylyl cyclase stimulators, have benefited patients with pulmonary artery hypertension. Likewise, the adjunctive symptomatic treatment of these patients has further improved the outcomes, since antiarrhythmics, digoxin, and non-steroidal anti-inflammatory drugs have shown their benefits in these cases. Conclusively, these drugs also carry the risk of troublesome adverse effects, such as electrolyte imbalances and hemodynamic compromise. However, their benefits for survival, symptom improvement, and stabilization outweigh the possible complications from their use. Thus, cases must be assessed individually to accurately identify interventions that would be most beneficial for patients.

Pharmacologic Management for Ventricular Arrhythmias: Overview of Anti-Arrhythmic Drugs

Ventricular arrhythmias (Vas) are a life-threatening condition and preventable cause of sudden cardiac death (SCD). With the increased utilization of implantable cardiac defibrillators (ICD), the focus of VA management has shifted toward reduction of morbidity from VAs and ICD therapies. Anti-arrhythmic drugs (AADs) can be an important adjunct therapy in the treatment of recurrent VAs. In the treatment of VAs secondary to structural heart disease, amiodarone remains the most well studied and current guideline-directed pharmacologic therapy. Beta blockers also serve as an important adjunct and are a largely underutilized medication with strong evidentiary support. In patients with defined syndromes in structurally normal hearts, AADs can offer tailored therapies in prevention of SCD and improvement in quality of life. Further clinical trials are warranted to investigate the role of newer therapeutic options and for the direct comparison of established AADs.

Adrenergic prolongation of action potential duration in rainbow trout myocardium via inhibition of the delayed rectifier potassium current, IKr

Catecholamines mediate the 'fight or flight' response in a wide variety of vertebrates. The endogenous catecholamine adrenaline increases heart rate and contractile strength to raise cardiac output. The increase in contractile force is driven in large part by an increase in myocyte Ca²⁺ influx on the L-type Ca current (I_CaL) during the cardiac action potential (AP). Here, we report a K⁺- based mechanism that prolongs AP duration (APD) in fish hearts following adrenergic stimulation. We show that adrenergic stimulation inhibits the delayed rectifier K⁺ current (I_Kr) in rainbow trout (Oncorhynchus mykiss) cardiomyocytes. This slows repolarization and prolongs APD which may contribute to positive inotropy following adrenergic stimulation in fish hearts. The endogenous ligand, adrenaline (1 μM), which activates both α- and β-ARs reduced maximal I_Kr tail current to 61.4 ± 3.9% of control in atrial and ventricular myocytes resulting in an APD prolongation of ~20% at both 50 and 90% repolarization. This effect was reproduced by the α-specific adrenergic agonist, phenylephrine (1 μM), but not the β-specific adrenergic agonist isoproterenol (1 μM). Adrenaline (1 μM) in the presence of β₁ and β₂-blockers (1 μM atenolol and 1 μM ICI-118551, respectively) also inhibited I_Kr. Thus, I_Kr suppression following α-adrenergic stimulation leads to APD prolongation in the rainbow trout heart. This is the first time this mechanism has been identified in fish and may act in unison with the well-known enhancement of I_CaL following adrenergic stimulation to prolong APD and increase cardiac inotropy.

A review of new-onset ventricular arrhythmia after left ventricular assist device implantation

INTRODUCTION

Heart failure (HF) is a severe and terminal stage of various heart diseases. Left ventricular assist devices (LVADs) are relatively mature and have contributed to the treatment of end-stage HF. Ventricular arrhythmia (VA) is a common complication after LVAD implantation, including ventricular tachycardia and ventricular fibrillation, both of which may cause abnormal circulation in the body.

METHODS

A literature search was conducted in the PubMed database, "Ventricular Arrhythmia" OR "VA" OR "Arrhythmia" OR "Ventricular Tachycardia," OR "Ventricular Fibrillation" AND "LVAD" OR "Left Ventricular Assist Device" OR "Heart Assist Device" as either keywords or MeSH terms, the authors screened the titles and abstracts of the articles. Eventually, 12 original research articles were retrieved.

RESULTS

The 0.83 [95%CI: 0.77, 0.89] of patients were male. A whole of 53% [95%CI:0.25, 0.81] of VA patients had a history of atrial fibrillation and 61% [95%CI:0.52, 0.69] had a history of VA. 39% [95%CI:0.29, 0.49] of the participants had no prior history of VA and experienced new VA following CF-LVAD implantation. Following CF-LVAD implantation, 59% [95%CI:0.51, 0.67] of patients developed the early VA (VA ≤ 30 days). The 30-day mortality of patients was 4% [95%CI:0.01, 0.07]. And overall mortality was 28% [95%CI:0.15, 0.41] The reported incidence of VA after LVAD implantation is not identical in different medical centers and ranges from 20% to 60%. The mechanism of VA after LVAD implantation is summarized as primary cardiomyopathy-related, device mechanical stimulation, myocardial scarring, ventricular displacement, electrolyte regulation, and other processes.

CONCLUSIONS

A preoperative VA history is considered a predictor of VA following LVAD implantation in most studies. Multiple mechanisms and factors, such as prevention of "suction events", ablation, and ICD, should be considered for the prevention and treatment of postoperative VA in patients requiring long-term VAD treatment. This study provides a reference for the clinical application of LAVD and the prevention of postoperative VA after LVAD implantation. Future multicenter prospective studies with uniform patient follow-up are needed to screen for additional potential risk factors and predictors. These studies will help to define the incidence rate of VA after LAVD implantation. As a result, we provide guidance for the selection of preventive intervention.

Integrated Pharmacogenetics Analysis of the Three Fangjis Decoctions for Treating Arrhythmias Based on Molecular Network Patterns

Aim: To explore the diverse target distribution and variable mechanisms of different fangjis prescriptions when treating arrhythmias based on the systems pharmacology.

Methods: The active ingredients and their corresponding targets were acquired from the three fangjis [Zhigancao Tang (ZT), Guizhigancao Longgumuli Tang (GLT), and Huanglian E'jiao Tang (HET)] and the arrhythmia-related genes were identified based on comprehensive database screening. Networks were constructed between the fangjis and arrhythmia and used to define arrhythmia modules. Common and differential gene targets were identified within the arrhythmia network modules and the cover rate (CR) matrix was applied to compare the contributions of the fangjis to the network and modules. Comparative pharmacogenetics analyses were then conducted to define the arrhythmia-related signaling pathways regulated by the fangjis prescriptions. Finally, the divergence and convergence points of the arrhythmia pathways were deciphered based on databases and the published literature.

Results: A total of 187, 105, and 68 active ingredients and 1,139, 1,195, and 811 corresponding gene targets of the three fangjis were obtained and 102 arrhythmia-related genes were acquired. An arrhythmia network was constructed and subdivided into 4 modules. For the target distribution analysis, 65.4% of genes were regulated by the three fangjis within the arrhythmia network. ZT and GLT were more similar to each other, mainly regulated by module two, whereas HET was divided among all the modules. From the perspective of signal transduction, calcium-related pathways [calcium, cyclic guanosine 3′,5′-monophosphate (cGMP)-PKG, and cyclic adenosine 3′,5′-monophosphate (cAMP)] and endocrine system-related pathways (oxytocin signaling pathway and renin secretion pathways) were associated with all the three fangjis prescriptions. Nevertheless, heterogeneity existed between the biological processes and pathway distribution among the three prescriptions. GLT and HET were particularly inclined toward the conditions involving abnormal hormone secretion, whereas ZT tended toward renin-angiotensin-aldosterone system (RAAS) disorders. However, calcium signaling-related pathways prominently feature in the pharmacological activities of the decoctions. Experimental validation indicated that ZT, GLT, and HET significantly shortened the duration of ventricular arrhythmia (VA) and downregulated the expression of CALM2 and interleukin-6 (IL-6) messenger RNAs (mRNAs); GLT and HET downregulated the expression of CALM1 and NOS3 mRNAs; HET downregulated the expression of CRP mRNA.

Conclusion: Comparing the various distributions of the three fangjis, pathways provide evidence with respect to precise applications toward individualized arrhythmia treatments.

Advances in Cardiac Pacing: Arrhythmia Prediction, Prevention and Control Strategies

Cardiac arrhythmias constitute a tremendous burden on healthcare and are the leading cause of mortality worldwide. An alarming number of people have been reported to manifest sudden cardiac death as the first symptom of cardiac arrhythmias, accounting for about 20% of all deaths annually. Furthermore, patients prone to atrial tachyarrhythmias such as atrial flutter and fibrillation often have associated comorbidities including hypertension, ischemic heart disease, valvular cardiomyopathy and increased risk of stroke. Technological advances in electrical stimulation and sensing modalities have led to the proliferation of medical devices including pacemakers and implantable defibrillators, aiming to restore normal cardiac rhythm. However, given the complex spatiotemporal dynamics and non-linearity of the human heart, predicting the onset of arrhythmias and preventing the transition from steady state to unstable rhythms has been an extremely challenging task. Defibrillatory shocks still remain the primary clinical intervention for lethal ventricular arrhythmias, yet patients with implantable cardioverter defibrillators often suffer from inappropriate shocks due to false positives and reduced quality of life. Here, we aim to present a comprehensive review of the current advances in cardiac arrhythmia prediction, prevention and control strategies. We provide an overview of traditional clinical arrhythmia management methods and describe promising potential pacing techniques for predicting the onset of abnormal rhythms and effectively suppressing cardiac arrhythmias. We also offer a clinical perspective on bridging the gap between basic and clinical science that would aid in the assimilation of promising anti-arrhythmic pacing strategies.

Autonomic modulation of ventricular electrical activity: recent developments and clinical implications

PURPOSE

This review aimed to provide a complete overview of the current stance and recent developments in antiarrhythmic neuromodulatory interventions, focusing on lifethreatening vetricular arrhythmias.

METHODS

Both preclinical studies and clinical studies were assessed to highlight the gaps in knowledge that remain to be answered and the necessary steps required to properly translate these strategies to the clinical setting.

RESULTS

Cardiac autonomic imbalance, characterized by chronic sympathoexcitation and parasympathetic withdrawal, destabilizes cardiac electrophysiology and promotes ventricular arrhythmogenesis. Therefore, neuromodulatory interventions that target the sympatho-vagal imbalance have emerged as promising antiarrhythmic strategies. These strategies are aimed at different parts of the cardiac neuraxis and directly or indirectly restore cardiac autonomic tone. These interventions include pharmacological blockade of sympathetic neurotransmitters and neuropeptides, cardiac sympathetic denervation, thoracic epidural anesthesia, and spinal cord and vagal nerve stimulation.

CONCLUSION

Neuromodulatory strategies have repeatedly been demonstrated to be highly effective and very promising anti-arrhythmic therapies. Nevertheless, there is still much room to gain in our understanding of neurocardiac physiology, refining the current neuromodulatory strategic options and elucidating the chronic effects of many of these strategic options.

Quantitative cross-species translators of cardiac myocyte electrophysiology: Model training, experimental validation, and applications

Animal experimentation is key in the evaluation of cardiac efficacy and safety of novel therapeutic compounds. However, interspecies differences in the mechanisms regulating excitation-contraction coupling can limit the translation of experimental findings from animal models to human physiology and undermine the assessment of drugs’ efficacy and safety. Here, we built a suite of translators for quantitatively mapping electrophysiological responses in ventricular myocytes across species. We trained these statistical operators using a broad dataset obtained by simulating populations of our biophysically detailed computational models of action potential and Ca2+ transient in mouse, rabbit, and human. We then tested our translators against experimental data describing the response to stimuli, such as ion channel block, change in beating rate, and β-adrenergic challenge. We demonstrate that this approach is well suited to predicting the effects of perturbations across different species or experimental conditions and suggest its integration into mechanistic studies and drug development pipelines.

Beta-blockers in patients without heart failure after myocardial infarction

BACKGROUND

Cardiovascular disease is the number one cause of death globally. According to the World Health Organization (WHO), 7.4 million people died from ischaemic heart disease in 2012, constituting 15% of all deaths. Beta-blockers are recommended and are often used in patients with heart failure after acute myocardial infarction. However, it is currently unclear whether beta-blockers should be used in patients without heart failure after acute myocardial infarction. Previous meta-analyses on the topic have shown conflicting results. No previous systematic review using Cochrane methods has assessed the effects of beta-blockers in patients without heart failure after acute myocardial infarction.

OBJECTIVES

To assess the benefits and harms of beta-blockers compared with placebo or no treatment in patients without heart failure and with left ventricular ejection fraction (LVEF) greater than 40% in the non-acute phase after myocardial infarction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index - Expanded, BIOSIS Citation Index, the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, European Medicines Agency, Food and Drug Administration, Turning Research Into Practice, Google Scholar, and SciSearch from their inception to February 2021.

SELECTION CRITERIA

We included all randomised clinical trials assessing effects of beta-blockers versus control (placebo or no treatment) in patients without heart failure after myocardial infarction, irrespective of publication type and status, date, and language. We excluded trials randomising participants with diagnosed heart failure at the time of randomisation.

DATA COLLECTION AND ANALYSIS

We followed our published protocol, with a few changes made, and methodological recommendations provided by Cochrane and Jakobsen and colleagues. Two review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse events, and major cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial reinfarction). Our secondary outcomes were quality of life, angina, cardiovascular mortality, and myocardial infarction during follow-up. We assessed all outcomes at maximum follow-up. We systematically assessed risks of bias using seven bias domains and we assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 25 trials randomising a total of 22,423 participants (mean age 56.9 years). All trials and outcomes were at high risk of bias. In all, 24 of 25 trials included a mixed group of participants with ST-elevation myocardial infarction and non-ST myocardial infarction, and no trials provided separate results for each type of infarction. One trial included participants with only ST-elevation myocardial infarction. All trials except one included participants younger than 75 years of age. Methods used to exclude heart failure were various and were likely insufficient. A total of 21 trials used placebo, and four trials used no intervention, as the comparator. All patients received usual care; 24 of 25 trials were from the pre-reperfusion era (published from 1974 to 1999), and only one trial was from the reperfusion era (published in 2018). The certainty of evidence was moderate to low for all outcomes. Our meta-analyses show that beta-blockers compared with placebo or no intervention probably reduce the risks of all-cause mortality (risk ratio (RR) 0.81, 97.5% confidence interval (CI) 0.73 to 0.90; I² = 15%; 22,085 participants, 21 trials; moderate-certainty evidence) and myocardial reinfarction (RR 0.76, 98% CI 0.69 to 0.88; I² = 0%; 19,606 participants, 19 trials; moderate-certainty evidence). Our meta-analyses show that beta-blockers compared with placebo or no intervention may reduce the risks of major cardiovascular events (RR 0.72, 97.5% CI 0.69 to 0.84; 14,994 participants, 15 trials; low-certainty evidence) and cardiovascular mortality (RR 0.73, 98% CI 0.68 to 0.85; I² = 47%; 21,763 participants, 19 trials; low-certainty evidence). Hence, evidence seems to suggest that beta-blockers versus placebo or no treatment may result in a minimum reduction of 10% in RR for risks of all-cause mortality, major cardiovascular events, cardiovascular mortality, and myocardial infarction. However, beta-blockers compared with placebo or no intervention may not affect the risk of angina (RR 1.04, 98% CI 0.93 to 1.13; I² = 0%; 7115 participants, 5 trials; low-certainty evidence). No trials provided data on serious adverse events according to good clinical practice from the International Committee for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH-GCP), nor on quality of life.

AUTHORS' CONCLUSIONS

Beta-blockers probably reduce the risks of all-cause mortality and myocardial reinfarction in patients younger than 75 years of age without heart failure following acute myocardial infarction. Beta-blockers may further reduce the risks of major cardiovascular events and cardiovascular mortality compared with placebo or no intervention in patients younger than 75 years of age without heart failure following acute myocardial infarction. These effects could, however, be driven by patients with unrecognised heart failure. The effects of beta-blockers on serious adverse events, angina, and quality of life are unclear due to sparse data or no data at all. All trials and outcomes were at high risk of bias, and incomplete outcome data bias alone could account for the effect seen when major cardiovascular events, angina, and myocardial infarction are assessed. The evidence in this review is of moderate to low certainty, and the true result may depart substantially from the results presented here. Future trials should particularly focus on patients 75 years of age and older, and on assessment of serious adverse events according to ICH-GCP and quality of life. Newer randomised clinical trials at low risk of bias and at low risk of random errors are needed if the benefits and harms of beta-blockers in contemporary patients without heart failure following acute myocardial infarction are to be assessed properly. Such trials ought to be designed according to the SPIRIT statement and reported according to the CONSORT statement.

Dynamic Electrocardiogram under P Wave Detection Algorithm Combined with Low-Dose Betaloc in Diagnosis and Treatment of Patients with Arrhythmia after Hepatocarcinoma Resection

This work aimed to study the diagnostic value of dynamic electrocardiogram (ECG) based on P wave detection algorithm for arrhythmia after hepatectomy in patients with primary liver cancer, and to compare the therapeutic effect of different doses of Betaloc. P wave detection algorithm was introduced for ECG automatic detection and analysis, which can be used for early diagnosis of arrhythmia. Sixty patients with arrhythmia after hepatectomy for primary liver cancer were selected as the research objects. They were randomly divided into control group, SD group, MD group, and HD group, with 15 cases in each group. No Betaloc, low-dose (≤47.5 mg), medium-dose (47.5-95 mg), and high-dose (142.5-190 mg) Betaloc were used for treatment. As a result, P wave detection algorithms can mark P waves that may be submerged in strong interference. P waves from arrhythmia database were used to verify the performance of the proposed algorithm. The prediction precision (Pp) of ventricular arrhythmia and atrial arrhythmia was 98.53% and 98.76%, respectively. Systolic blood pressure (117.35 ± 7.33, 126.44 ± 9.38, and 116.02 ± 8.2) mmHg in SD group, MD group, and HD group was significantly lower than that in control group (140.3 ± 7.21) mmHg after two weeks of treatment. Moreover, those of SD group and HD group were significantly lower than MD group (P < 0.05). The effective rate of cardiac function improvement in SD group (72.35 ± 1.21%) was significantly higher than that in control group, MD group, and HD group (38.2 ± 0.98%, 65.12 ± 1.33%, and 60.43 ± 1.25%; P < 0.05). In short, dynamic ECG based on P wave detection algorithm had high diagnostic value for arrhythmia after hepatectomy in patients with primary liver cancer. It was safe and effective for patients to choose small dose of Betaloc.

The Use of β-Blockers in Heart Failure with Reduced Ejection Fraction

Treatment with β-blockers is the main strategy for managing patients with heart failure and reduced ejection fraction because of their ability to reverse the neurohumoral effects of the sympathetic nervous system, with consequent prognostic and symptomatic benefits. However, to date, they are underused, mainly because of the misconception that hypotension and bradycardia may worsen the haemodynamic status of patients with HFrEF and because of the presence of comorbidities falsely believed to be absolute contraindications to their use. To promote proper use of β-blockers in this article, we review the clinical pharmacology of β-blockers, the evidence of the beneficial effects of these drugs in heart failure with reduced ejection fraction, and the current guidelines for their use in clinical practice and in the presence of comorbidities (e.g., pulmonary disease, diabetes, atrial fibrillation, peripheral arterial disease, etc.). It is hoped that the practical approach discussed in this review will allow for a proper diffusion of knowledge about the correct use of β-blockers and the drug-disease interactions to achieve their increased use and titration, as well as for the selection of a specific agent with a view to a properly tailored approach for HFrEF patients.

Aggressive beta-blocker titration in stabilized acute heart failure patients with low left ventricular ejection fraction

Objectives

A beta-blocker should be initiated in patients with stable acute heart failure (AHF). Beta-blocker titration should be conducted after a two-week interval. The benefits of aggressive beta-blocker titration are still unclear. This study aimed to investigate the aggressive beta-blocker titration outcomes in stabilized AHF patients with low left ventricular ejection fraction (LVEF).

Methods

In this retrospective cohort study, we analysed clinical data from the heart failure (HF) registry. AHF Patients with LVEF <40% were divided into aggressive and guideline-directed beta-blocker titration groups. The composite of worsening HF, ventricular arrhythmia, and mortality during hospitalization were defined as the primary outcomes. We considered secondary outcomes as the components of primary outcomes and also the outcomes during a 90-day follow-up after hospital discharge, including HF readmission and mortality.

Results

The primary outcomes between both groups were not significantly different (12.3% vs 24.4%; relative risk [RR] 0.51; 95% confidence interval [CI] 0.25–1.01; p = 0.055). However, the aggressive beta-blocker titration reduced ventricular arrhythmia events (5.7% vs 17.8%; RR 0.32; 95% CI 0.12–0.84; p = 0.016). The 90-day HF readmission rate (2.6% vs 7.5%; RR 0.35; 95% CI 0.07–1.66; p = 0.179) and mortality rate (4.3% vs 5%; RR 0.87; 95% CI 0.18–4.31; p = 1.000) between both groups were not found to be significantly different.

Conclusion

Compared to the guideline-directed beta-blocker titration, the aggressive beta-blocker titration was safe in low LVEF AHF patients who have been previously stabilized. Additionally, aggressive beta-blocker titration effectively reduced ventricular arrhythmia events.

Synergistic antiarrhythmic effect of inward rectifier current inhibition and pulmonary vein isolation in a 3D computer model for atrial fibrillation

AIMS

Recent clinical studies showed that antiarrhythmic drug (AAD) treatment and pulmonary vein isolation (PVI) synergistically reduce atrial fibrillation (AF) recurrences after initially successful ablation. Among newly developed atrial-selective AADs, inhibitors of the G-protein-gated acetylcholine-activated inward rectifier current (IKACh) were shown to effectively suppress AF in an experimental model but have not yet been evaluated clinically. We tested in silico whether inhibition of inward rectifier current or its combination with PVI reduces AF inducibility.

METHODS AND RESULTS

We simulated the effect of inward rectifier current blockade (IK blockade), PVI, and their combination on AF inducibility in a detailed three-dimensional model of the human atria with different degrees of fibrosis. IK blockade was simulated with a 30% reduction of its conductivity. Atrial fibrillation was initiated using incremental pacing applied at 20 different locations, in both atria. IK blockade effectively prevented AF induction in simulations without fibrosis as did PVI in simulations without fibrosis and with moderate fibrosis. Both interventions lost their efficacy in severe fibrosis. The combination of IK blockade and PVI prevented AF in simulations without fibrosis, with moderate fibrosis, and even with severe fibrosis. The combined therapy strongly decreased the number of fibrillation waves, due to a synergistic reduction of wavefront generation rate while the wavefront lifespan remained unchanged.

CONCLUSION

Newly developed blockers of atrial-specific inward rectifier currents, such as IKAch, might prevent AF occurrences and when combined with PVI effectively supress AF recurrences in human.

Return-to-Play for Athletes With Long QT Syndrome or Genetic Heart Diseases Predisposing to Sudden Death

BACKGROUND

Within the last 5 years, cardiac society guidelines have begun to acknowledge shared decision making (SDM) for the athlete with sudden cardiac death-predisposing genetic heart diseases (GHDs), such as long QT syndrome (LQTS), and the possibility for that athlete's return to play. Previously, international guidelines embraced a de facto disqualification for all such athletes including athletes with solely a positive genetic test in Europe.

OBJECTIVES

This study sought to examine the prevalence and outcomes of athletes with sudden cardiac death-predisposing GHDs, particularly LQTS, after their return to play.

METHODS

A retrospective review of the electronic medical record was performed on all athletes with GHD, with a primary analysis for those with LQTS, who were evaluated, risk stratified, and treated in Mayo Clinic's Windland Smith Rice Genetic Heart Rhythm Clinic by a single genetic cardiologist between July 1, 2000, and July 31, 2020.

RESULTS

There were 672 athletes with GHD overall including 494 athletes with LQTS (231 female athletes [46.8%]; mean age at diagnosis 14.8 ± 10.5 years; mean follow-up 4.2 ± 4.8 years) who were given return-to-play approval. Overall, 79 of 494 athletes with LQTS (16.0%) were symptomatic before diagnosis, and 58 (11.7%) had an implantable cardioverter-defibrillator. In 2,056 combined years of follow-up, there was no GHD-sports associated mortality. Instead, 29 patients (5.9%) had ≥1 nonlethal, LQTS-associated breakthrough cardiac event. Of those, 15 (3.0%) were athletes at the time of the breakthrough cardiac event, with 3 (0.6%) experiencing a sports-related breakthrough cardiac event, and 12 (2.4%) a non-sports-related event. Overall, the event rate was 1.16 nonlethal events per 100 athlete-years of follow-up.

CONCLUSIONS

This 20-year single center experience challenges the status quo of disqualification for all athletes with LQTS and provides additional observational evidence, albeit from a single center, in support of the more contemporary SDM approaches to this complex issue.

OASIS +: leveraging machine learning to improve the prognostic accuracy of OASIS severity score for predicting in-hospital mortality

Background

Severity scores assess the acuity of critical illness by penalizing for the deviation of physiologic measurements from normal and aggregating these penalties (also called “weights” or “subscores”) into a final score (or probability) for quantifying the severity of critical illness (or the likelihood of in-hospital mortality). Although these simple additive models are human readable and interpretable, their predictive performance needs to be further improved.

Methods

We present OASIS +, a variant of the Oxford Acute Severity of Illness Score (OASIS) in which an ensemble of 200 decision trees is used to predict in-hospital mortality based on the 10 same clinical variables in OASIS.

Results

Using a test set of 9566 admissions extracted from the MIMIC-III database, we show that OASIS + outperforms nine previously developed severity scoring methods (including OASIS) in predicting in-hospital mortality. Furthermore, our results show that the supervised learning algorithms considered in our experiments demonstrated higher predictive performance when trained using the observed clinical variables as opposed to OASIS subscores.

Conclusions

Our results suggest that there is room for improving the prognostic accuracy of the OASIS severity scores by replacing the simple linear additive scoring function with more sophisticated non-linear machine learning models such as RF and XGB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12911-021-01517-7.