Use of beta-blockers in atrial fibrillation

Inhibitors of Intracellular RyR2 Calcium Release Channels as Therapeutic Agents in Arrhythmogenic Heart Diseases

Ryanodine receptor type 2 (RyR2) is the principal intracellular calcium release channel in the cardiac sarcoplasmic reticulum (SR). Pathological RyR2 hyperactivity generates arrhythmia risk in genetic and structural heart diseases. RYR2 gain-of-function mutations cause catecholaminergic polymorphic ventricular tachycardia. In structural heart diseases (i.e., heart failure), posttranslation modifications render RyR2 channels leaky, resulting in pathologic calcium release during diastole, contributing to arrhythmogenesis and contractile dysfunction. Hence, RyR2 represents a therapeutic target in arrhythmogenic heart diseases. We provide an overview of the structure and function of RyR2, and then review US Food and Drug Administration-approved and investigational RyR2 inhibitors. A therapeutic classification of RyR2 inhibitors is proposed based on their mechanism of action. Class I RyR2 inhibitors (e.g., flecainide) do not change SR calcium content and are primarily antiarrhythmic. Class II RyR2 inhibitors (e.g., dantrolene) increase SR calcium content, making them less effective as antiarrhythmics but preferable in conditions with reduced SR calcium content such as heart failure.

Implications of Atrial Fibrillation for Guideline-Directed Therapy in Patients With Heart Failure: JACC State-of-the-Art Review

Atrial fibrillation (AF) and heart failure (HF) are common cardiovascular conditions that frequently coexist. Among patients with HF, more than one-half also have AF. Both are associated with significant morbidity and mortality. Moreover, the prevalence of each is increasing globally, and this trend is expected to continue owing to an aging population and increased life expectancy. Diagnosis of AF in a patient with HF is associated with greater symptom burden, more frequent hospitalizations, and a worse prognosis. Guideline-directed medical therapy (GDMT) for HF can affect the incidence of AF. Once present, AF can influence the efficacy of some components of GDMT for HF. In this review, we discuss the effect of GDMT for HF across the spectrum of ejection fraction on prevention of AF as well as the benefit of GDMT in patients with vs without AF.

Consensus document on palliative care in cardiorenal patients

There is an unmet need to create consensus documents on the management of cardiorenal patients since, due to the aging of the population and the rise of both pathologies, these patients are becoming more prevalent in daily clinical practice. Chronic kidney disease coexists in up to 40%-50% of patients with chronic heart failure cases. There have yet to be consensus documents on how to approach palliative care in cardiorenal patients. There are guidelines for patients with heart failure and chronic kidney disease separately, but they do not specifically address patients with concomitant heart failure and kidney disease. For this reason, our document includes experts from different specialties, who will not only address the justification of palliative care in cardiorenal patients but also how to identify this patient profile, the shared planning of their care, as well as knowledge of their trajectory and the palliative patient management both in the drugs that will help us control symptoms and in advanced measures. Dialysis and its different types will also be addressed, as palliative measures and when the decision to continue or not perform them could be considered. Finally, the psychosocial approach and adapted pharmacotherapy will be discussed.

Autonomic Nervous System and Cardiac Metabolism: Links Between Autonomic and Metabolic Remodeling in Atrial Fibrillation

Simultaneous activation of the sympathetic and parasympathetic nervous systems is crucial for the initiation of paroxysmal atrial fibrillation (AF). However, unbalanced activation of the sympathetic system is characteristic of autonomic remodeling in long-standing persistent AF. Moreover, the adrenergic activation-induced metabolic derangements provide a milieu for acute AF and promote the transition from the paroxysmal to the persistent phase of AF. On the other hand, cholinergic activation ameliorates the maladaptive metabolic remodeling in the face of metabolic challenges. Selective inhibition of the sympathetic system and restoration of the balance of the cholinergic system by neuromodulation is emerging as a novel nonpharmacologic strategy for managing AF. This review explores the link between cardiac autonomic and metabolic remodeling and the potential roles of different autonomic modulation strategies on atrial metabolic aberrations in AF.

Beta blocker versus ivabradine for cardiovascular outcomes among patients with atrial fibrillation

PURPOSE

We conducted a retrospective observational study using Taiwanese insurance records to examine the association between beta blocker (BB)/ ivabradine (IVA) and cardiovascular (CV) outcomes in patients with atrial fibrillation (AF).

METHODS

A total of 1884 AF subjects were enrolled. The propensity score-matching technique was applied to estimate the effect of IVA by accounting for the covariates. The CV outcomes included hospitalisation/rehospitalisation due to acute myocardial infarction, heart failure (HF), haemorrhagic stroke, ischaemic stroke, CV death and all-cause death. Univariate and multivariate Cox proportional hazards regression models were used to estimate crude and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

We reported a higher risk of HF requiring admission (adjusted HR=2.01; 95% CI 1.67 to 2.42), and all cause death (adjusted HR=1.47; 95% CI 1.11 to 1.94) after adjusting for age, sex, comorbidities and medications.

CONCLUSION

Concerning adverse clinical events, IVA might not be appropriate for patients with AF.

Paroxysmal and Non-Paroxysmal Atrial Fibrillation in Middle Eastern Patients: Clinical Features and the Use of Medications. Analysis of the Jordan Atrial Fibrillation (JoFib) Study

(1) Background: Atrial fibrillation (AF) is the most common arrhythmia causing an increased risk of mortality and morbidity. It is classified into paroxysmal and non-paroxysmal AF depending on the duration and frequency of the episodes. (2) Aims: Our goal was to investigate and compare the clinical profiles, risk of co-morbidities, the use of oral anticoagulation, and outcomes of patients with paroxysmal and non-paroxysmal AF in inpatient and outpatient settings. (3) Methods: Data were extracted from 28 different hospitals and centers in Jordan with a total of 2160 patients enrolled in the study using an observational non-interventional study model. The clinical features and the use of oral anticoagulants were compared in patients with paroxysmal and non-paroxysmal AF. (4) Results: Paroxysmal AF was documented in 35.6% (769) of the patients and non-paroxysmal types in 63.9% (1380); in addition, the type of AF was unknown in 11 (0.5%) patients. Our results showed that non-paroxysmal AF patients tend to be older with more co-morbidities and higher CHA2DS2-VASC and HAS-BLED scores. They also have higher rates of hypertension and diabetes. Anticoagulant, antiarrhythmic, and diuretic agents, overall, were used more in non-paroxysmal AF than paroxysmal AF. Hospital admissions were also more frequent in non-paroxysmal AF due to various factors, some of which are heart failure, bleeding risk, and COPD. (5) Conclusions: Non-paroxysmal AF is more common among Jordanian AF patients. The prevalence of comorbidities and the use of different types of therapies, especially anticoagulants, were higher in these patients.

Rate versus rhythm control for atrial fibrillation: from AFFIRM to EAST-AFNET 4 - a paradigm shift

The clinical choice between rate or rhythm control therapies has been debated over the years. In 2002, the AFFIRM trial demonstrated that the rhythm-control strategy had no survival advantage over the rate-control strategy. Eighteen years later, EAST-AFNET 4 showed that the rhythm-control approach is better than rate control in reducing adverse cardiovascular outcomes in patients with a recent diagnosis of atrial fibrillation (AF). During the time between AFFIRM and EAST-AFNET 4, rhythm control understanding, specifically ablation, improved, while rate-control strategies remained the same possibly leading to the change in results seen in EAST-AFNET 4. This review seeks to evaluate the rate- and rhythm-control strategies, focusing on the important clinical trials in the past two decades. These trials have shown great advancement in AF management; however, the search for the best approach to controlling AF and minimizing the burden of symptoms is still a work in progress and needs further research.

Pharmacokinetics and pharmacodynamics of oral and intravenous metoprolol tartrate in clinically healthy horses

Cardiac drugs with defined pharmacological parameters in horses are limited. The objective of this study was to characterize the pharmacokinetic properties and cardiovascular effects of intravenous and oral metoprolol tartrate (MET) in horses. In a 2-period randomized cross-over design, MET was administered IV (0.04 mg/kg) and PO (6 mg/kg) once to six healthy adult horses. Horses were monitored via continuous telemetry and non-invasive blood pressure (NIBP). Blood samples were serially collected for 72 h post-administration, and concentrations were determined by LC-MS/MS. Pharmacokinetics were modeled using a 3-compartment model and non-linear least squares regression. Median (range) MET concentration was 110 (40.1-197) ng/ml collected 1 min (0.0167 h) after a bolus IV administration. Maximum concentration (C_max ) after PO administration was 2135 (1590-4170) ng/ml at 0.5 (0.25-0.5) hours. Oral bioavailability was 54% (17-100%). Median apparent volume of distribution was 0.39 (0.17-0.58) l/kg, clearance was 12.63 (11.41-18.94) ml/kg/min, and elimination half-life was 21.1 (7.46-34.36) minutes. No clinically relevant effects of IV or PO metoprolol were noted on cardiac rhythm or NIBP. Sweating was the most common side effect. The metoprolol doses used in this study achieve plasma concentrations reported to achieve ß-blockade in humans.

Benefits of prescribing low-dose digoxin in atrial fibrillation

INTRODUCTION

The role of digoxin (cardiac glycoside) in controlling the heart rate (HR) for the treatment of atrial fibrillation (AF) patients has not been explored in depth.

METHODS

To contribute to the limited data, our team conducted retrospective analysis of the clinical records of 1444 AF patients. We divided the AF patients into two groups, wherein group 1 patients were treated with beta-blockers (BB), low-dose digoxin, and an anticoagulant (vitamin K antagonist/factor-IIa inhibitor/factor-Xa inhibitor), and group 2 patients were treated with just BB and an anticoagulant. Our objectives were to compare the impact of combination therapy of BB and digoxin on the resting HR in patients with permanent AF and the patients' quality of life (QOL) at periodic intervals.

RESULTS

The findings of our study showed a better control of the resting HR rate (<110bpm) and an improved QOL among the group 1 patients when compared with group 2 patients.

CONCLUSION

Our findings are indicative of the favorable clinical outcomes that resulted from the addition of a low-dose of digoxin to the AF treatment regimen. However, larger studies/trials elucidating the outcomes of AF patients treated with the dual rate control therapy are required, to clarify the role of digoxin, guide the choice of agents, and standardize the AF treatment protocol.

Dynamic Electrocardiography is Useful in the Diagnosis of Persistent Atrial Fibrillation Accompanied with Second-Degree Atrioventricular Block

BACKGROUND

Periodic electrocardiography (ECG) at every clinical visit is generally performed for heart rhythm surveillance, and 24-h Holter ECG is usually used as the gold standard. We aimed to investigate the electrocardiographic features of persistent atrial fibrillation (AF) accompanied with second-degree atrioventricular block (AVB).

METHODS

From October 2012 to November 2015, 204 patients with an RR interval > 2.0 s before radiofrequency ablation were included. Dynamic ECG (DCG) was performed before and after the radiofrequency ablation. The patients were divided into two groups based on changes in DCG after radiofrequency ablation: group A (non-second-degree AVB group) and group B (second-degree AVB group). An RR interval > 2.0 s, the distribution of escape rhythm, mean heart rate and the long RR interval in the two groups were analyzed.

RESULTS

After radiofrequency ablation, all 204 patients who had persistent AF converted to sinus rhythm successfully. In group A (n = 193), the distribution of an RR interval > 2.0 s and escape rhythm were significantly correlated with sleep or rest, while no correlation was observed in group B (n = 11). The average RR interval prolongation and escape rhythm were significantly higher in group B than in group A (p < 0.05). The average number of long RR intervals > 3.0 s and average number of escape rhythm episodes (< 35 bpm) were significant predictive factors of second-degree AVB after radiofrequency ablation.

CONCLUSIONS

DCG is a useful tool for the diagnosis of persistent AF accompanied with second-degree AVB.

Use of statins and antihypertensive medications in relation to risk of long-standing persistent atrial fibrillation

BACKGROUND

After an initial episode of atrial fibrillation (AF), patients may develop long-standing persistent or permanent AF.

OBJECTIVE

We evaluated whether use of statins, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), or β-blockers is associated with lower risk of long-standing persistent AF after an initial AF episode.

METHODS

We conducted a population-based inception cohort study of participants enrolled in Group Health, aged 30 to 84 years, with newly diagnosed AF in 2001-2004. We included only participants whose initial AF episode terminated within 6 months of onset. We ascertained the primary outcome of long-standing persistent AF from medical records, electrocardiograms, and administrative data. We determined time-varying medication use from Group Health pharmacy data.

RESULTS

Among 1317 participants with incident AF, 304 developed long-standing persistent AF. Our study suggests that current statin use versus never use may be associated with lower risk for long-standing persistent AF. However, the association was not statistically significant when adjusted for age, sex, cardiovascular risk factors, and current use of antiarrhythmic medication (hazard ratio [HR] = 0.77; 95% CI = 0.57, 1.03). In lagged analyses intended to reduce healthy user bias, current statin use 1 year prior versus never use 1 year prior was not associated with risk for long-standing persistent AF (HR = 0.91; 95% CI = 0.67, 1.24). ACE inhibitor, ARB, and β-blocker use were not associated with risk for long-standing persistent AF.

CONCLUSIONS

Current statin use may confer protection that wanes after discontinuing use. Alternatively, healthy user bias or chance may explain the association. The association of statin use with long-standing persistent AF warrants further investigation.

Looking into a conceptual framework of ROS-miRNA-atrial fibrillation

Atrial fibrillation (AF) has been recognized as a major cause of cardiovascular-related morbidity and mortality. MicroRNAs (miRNAs) represent recent additions to the collection of biomolecules involved in arrhythmogenesis. Reactive oxygen species (ROS) have been independently linked to both AF and miRNA regulation. However, no attempts have been made to investigate the possibility of a framework composed of ROS–miRNA–AF that is related to arrhythmia development. Therefore, this review was designed as an attempt to offer a new approach to understanding AF pathogenesis. The aim of this review was to find and to summarize possible connections that exist among AF, miRNAs and ROS to understand the interactions among the molecular entities underlying arrhythmia development in the hopes of finding unappreciated mechanisms of AF. These findings may lead us to innovative therapies for AF, which can be a life-threatening heart condition. A systemic literature review indicated that miRNAs associated with AF might be regulated by ROS, suggesting the possibility that miRNAs translate cellular stressors, such as ROS, into AF pathogenesis. Further studies with a more appropriate experimental design to either prove or disprove the existence of an ROS–miRNA–AF framework are strongly encouraged.

New insights into cardiac resynchronization therapy

Ventricular dyssynchrony plays a central role in the expression and progression of heart failure (HF). An independent risk factor for cardiac mortality, ventricular dyssynchrony is characterized by delay in left ventricular (LV) lateral wall contraction. This leads to decreased pumping efficiency, with resulting fluid retention and impaired exercise tolerance. Cardiac resynchronization therapy (CRT) attempts to improve cardiac efficiency by restoring the normal mechanical relationship between right and left ventricular contraction. Cardiac output increases with resynchronization, while ventricular filling pressure decreases without increasing cardiac oxygen consumption. Cardiac resynchronization therapy can also reverse LV dysfunction and reduce mitral regurgitation in patients with HF. Since 1999, the efficacy of implantable CRT devices has been evaluated in clinical trials enrolling more than 4,000 patients with heart disease. In the CARE-HF trial, CRT reduced the risk of death by 36% relative to standard pharmacologic therapy. Combining CRT with a defibrillator might produce an added benefit. In the COMPANION trial, all-cause mortality in patients randomized to a CRT-defibrillator combination was less than in patients receiving CRT therapy alone. Cardiac resynchronization therapy has also been found to decrease morbidity and improve functional status and quality of life. At the present time, the indications for CRT are limited and include symptomatic HF despite optimal medical therapy, prolonged QRS interval, and LVEF < or = 35%. However, indications for CRT are still evolving and may be expanded as further studies identify those most likely to benefit.