A randomized controlled trial to prevent post-operative atrial fibrillation by antioxidant reinforcement

Pre- and post-operative administration of omega-3 polyunsaturated fatty acids in cardiac surgery patients. A narrative review

Eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are two biologically active omega-3 polyunsaturated fatty acids (n-3 PUFA), acquired by nutrition and incorporated in cell membranes' phospholipids, thus playing a crucial role in human health and homeostasis. Due to their potential cardioprotective, anti-inflammatory, and anti-arrhythmic actions, n-3 PUFA emerge as an interesting therapeutic option for cardiac surgery (CS) patients. The aim of this review was to assess the effects of perioperative administration of n-3 PUFA in CS patients. A comprehensive literature search was conducted in order to identify prospective cohort studies and randomized controlled trials (RCT) reporting on the perioperative effects of n-3 PUFA among adult patients undergoing CS. A total of 31 articles, published between 1995 and 2022, including 10 543 patients, met the inclusion criteria. There seems to be a beneficial effect of n-3 PUFA supplementation for arrhythmias such as in Postoperative Atrial Fibrillation (POAF), reduction of Intensive Care Unit Length of Stay (ICULOS) & Hospital Length of Stay (HLOS), reduction in postoperative ventilation time, in inotropic demand, in postoperative fatigue, as well as in overall morbidity and mortality. Moreover, n-3 PUFA increase antioxidant potential, attenuate oxidative stress and inflammation with subsequent significant reduction in myocardial ischemia/reperfusion (I/R) injury, thus promoting early metabolic recovery of the heart after elective CS leading to improved myocardial protection. They represent a readily available and cost-effective strategy that could improve the outcome of patients undergoing CS, by reducing the risks of serious cardiovascular adverse events (AE), both peri- and post-operatively.

Effect of Combined Vitamin C and Thiamine Therapy on Myocardial and Inflammatory Markers in Cardiac Surgery: A Randomized Controlled Clinical Trial

Background: Oxidative stress and systemic inflammation during cardiac surgery can lead to postoperative complications. Although vitamin C and thiamine (vitamin B1) have individually demonstrated protective effects, their combined effects remain underexplored. This study aimed to evaluate the efficacy of combined vitamin C and B1 therapy versus that of vitamin C alone in reducing inflammatory and cardiac biomarkers and improving postoperative outcomes in patients undergoing cardiac surgery. Methods: In this prospective, double-blind, randomized controlled trial, 64 patients scheduled for elective cardiac surgery at a tertiary care center were randomized to receive either 1000 mg vitamin C or a combination of 1000 mg vitamin C and 100 mg vitamin B1 at four perioperative time points. Primary outcomes included changes in inflammatory biomarkers [C-reactive protein, interleukin-6 (IL-6), and white blood cells], and cardiac biomarkers [creatine kinase-MB, Troponin-I, and lactate dehydrogenase]. Secondary outcomes included hemodynamic parameters and left ventricular function. Results: Compared with vitamin C alone, combined vitamin B1 and vitamin C significantly reduced postoperative cardiac biomarker levels. IL-6 levels were significantly lower immediately in the combined group; however, this effect was not sustained at 24 h post-surgery. Up to 24 h after surgery, no significant differences in hemodynamic stability or left ventricular ejection were observed between the groups. Notably, the combined therapy group demonstrated a lower incidence of postoperative arrhythmias and shorter dobutamine duration within 24 postoperatively. Conclusions: Combined vitamin C and B1 therapy significantly reduced markers of myocardial injury and early inflammatory responses (IL-6) in patients undergoing cardiac surgery, suggesting its potential as a protective agent.

Role of NLRP3 Inflammasome in Heart Failure Patients Undergoing Cardiac Surgery as a Potential Determinant of Postoperative Atrial Fibrillation and Remodeling: Is SGLT2 Cotransporter Inhibition an Alternative for Cardioprotection?

In heart failure (HF) patients undergoing cardiac surgery, an increased activity of mechanisms related to cardiac remodeling may determine a higher risk of postoperative atrial fibrillation (POAF). Given that atrial fibrillation (AF) has a negative impact on the course and management of HF, including the need for anticoagulation therapy, identifying the factors associated with AF occurrence after cardiac surgery is crucial for the prognosis of these patients. POAF is thought to occur when various clinical and biochemical triggers act on susceptible cardiac tissue (first hit), with oxidative stress and inflammation during cardiopulmonary bypass (CPB) surgery being potential contributing factors (second hit). However, the molecular mechanisms involved in these processes remain poorly characterized. Recent research has shown that patients who later develop POAF often have pre-existing abnormalities in calcium handling and activation of NLRP3-inflammasome signaling in their atrial cardiomyocytes. These molecular changes may make cardiomyocytes more susceptible to spontaneous Ca2+-releases and subsequent arrhythmias, particularly when exposed to inflammatory mediators. Additionally, some clinical studies have linked POAF with elevated preoperative inflammatory markers, but there is a need for further research in order to better understand the impact of CPB surgery on local and systemic inflammation. This knowledge would make it possible to determine whether patients susceptible to POAF have pre-existing inflammatory conditions or cellular electrophysiological factors that make them more prone to developing AF and cardiac remodeling. In this context, the NLRP3 inflammasome, expressed in cardiomyocytes and cardiac fibroblasts, has been identified as playing a key role in the development of HF and AF, making patients with pre-existing HF with reduced ejection fraction (HFrEF) the focus of several clinical studies with interventions that act at this level. On the other hand, HFpEF has been linked to metabolic and non-ischemic risk factors, but more research is needed to better characterize the myocardial remodeling events associated with HFpEF. Therefore, since ventricular remodeling may differ between HFrEF and HFpEF, it is necessary to perform studies in both groups of patients due to their pathophysiological variations. Clinical evidence has shown that pharmacological therapies that are effective for HFrEF may not provide the same anti-remodeling benefits in HFpEF patients, particularly compared to traditional adrenergic and renin-angiotensin-aldosterone system inhibitors. On the other hand, there is growing interest in medications with pleiotropic or antioxidant/anti-inflammatory effects, such as sodium-glucose cotransporter 2 inhibitors (SGLT-2is). These drugs may offer anti-remodeling effects in both HFrEF and HFpEF by inhibiting pro-inflammatory, pro-oxidant, and NLRP3 signaling pathways and their mediators. The anti-inflammatory, antioxidant, and anti-remodeling effects of SGLT-2 i have progressively expanded from HFrEF and HFpEF to other forms of cardiac remodeling. However, these advances in research have not yet encompassed POAF despite its associations with inflammation, oxidative stress, and remodeling. Currently, the direct or indirect effects of NLRP3-dependent pathway inhibition on the occurrence of POAF have not been clinically assessed. However, given that NLRP3 pathway inhibition may also indirectly affect other pathways, such as inhibition of NF-kappaB or inhibition of matrix synthesis, which are strongly linked to POAF and cardiac remodeling, it is reasonable to hypothesize that this type of intervention could play a role in preventing these events.

Mediterranean diet and atrial fibrillation: a case-control study from China

Objective

The aim of this study was to assess the association between adherence to Mediterranean diet and the presence of atrial fibrillation (AF) in a Northern Chinese population.

Methods

This study was a single center, case-control study. A total of 952 low risk participants in Beijing Anzhen Hospital from 2016 to 2021 were collected, including 476 patients with first diagnosed of atrial fibrillation and 476 age and sex matched controls. According to the food frequency questionnaire (FFQ), the alternate Mediterranean diet score (AMED) was calculated, which was 0-9 points, indicating the adherence to the Mediterranean diet from low to high.

Results

The average age of the participants was 57.6 ± 9.1 years old, and 70.2% were men. After analyzing every component of AMED, vegetable consumption shows a negative correlation with the risk of AF, whereas alcohol consumption demonstrates a positive correlation with it (OR = 0.61, 95% CI 0.44-0.80, p < 0.001; OR = 1.99, 95% CI 1.48-2.58, p < 0.001). All patients were grouped according to AMED score. A significant inverse association between AMED and the risk of AF was observed. Compared with participants with AMED<4, the multivariable-adjusted ORs of AF were 0.75 (95% CI 0.55-1.06) for AMED 4-5 and 0.61 (95% CI 0.43-0.89) for AMED ≥6, with a trend in risk (p = 0.008). Results were consistent in stratified analyses of gender, age, BMI and smoking.

Conclusion

The Mediterranean diet was inversely associated with the risk of AF in this Northern Chinese population.

Efficacy and Safety of Omega-3 Fatty Acids in the Prevention of Cardiovascular Disease: A Systematic Review and Meta-analysis

BACKGROUND

It is widely accepted that omega-3 fatty acids are beneficial in the prevention of cardiovascular disease, but many large randomized controlled trial studies and meta-analyses have come to different conclusions. The evidence for omega-3 fatty acids supplementation to prevent cardiovascular disease remains insufficient. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of several types of omega-3 fatty acids supplements.

METHODS

We comprehensively searched the online database and found 15 RCTs. The primary efficacy outcomes included major cardiovascular events, myocardial infarction, heart failure, atrial fibrillation, stroke, cardiovascular death, and all-cause death. The safety endpoints included gastrointestinal problems, bleeding-related disorders, and cancer. Subgroup analysis was conducted according to the main characteristics of the population, and the dose-response relationship of omega-3 fatty acids was evaluated by meta-regression. All results were calculated by the random effect model. Statistical heterogeneity was assessed using chi-square tests and quantified using I-square statistics.

RESULTS

The incidence of major cardiovascular events (RR 0.95, 95%CI 0.91 to 0.99, P = 0.026), myocardial infarction (RR 0.90, 95%CI 0.83 to 0.98; P = 0.021), and cardiovascular death (RR 0.94, 95%CI 0.88 to 0.99; P = 0.028) was reduced in the omega-3 fatty acid group compared with the control group. An increased risk of atrial fibrillation (RR 1.25, 95%CI 1.10 to 1.41; P = 0.000) was observed in patients in the omega-3 fatty acid group. No statistical differences were observed between the two groups in heart failure, stroke, and all-cause death. For safety endpoints, there were no statistically significant differences between the two groups in gastrointestinal problems, bleeding-related disorders, and cancer. Subgroup analysis showed that the cardiovascular benefit of omega-3 fatty acids was primarily attributable to the prescription of EPA ethyl ester. Omega-3 fatty acids may reduce the risk of major cardiovascular events in patients with cardiovascular disease or risk factors, and reduce the risk of myocardial infarction in patients without cardiovascular disease; however, they may increase the risk of stroke in patients with myocardial infarction. In addition, prescription omega-3 acid ethyl ester has a good safety profile, and prescription EPA ethyl ester has a high risk of bleeding.

CONCLUSION

Moderate evidence showed that the use of omega-3 fatty acids may reduce the risk of major cardiovascular events, myocardial infarction, and cardiovascular death. Compared to other types of omega-3 fatty acids supplements, we support the use of prescription EPA ethyl ester formulations for the prevention of cardiovascular disease, but the potential risk of atrial fibrillation and bleeding cannot be ignored. It is important to note that omega-3 fatty acids should be applied with caution in patients with previous myocardial infarction, which may increase the risk of stroke. Finally, omega-3 fatty acids are relatively safe and in general do not increase gastrointestinal problems, bleeding-related disorders, or cancer, but attention needs to be paid to the risk of bleeding with prescription EPA ethyl ester formulations.

Factors predicting the recurrence of atrial fibrillation after catheter ablation: A review

Atrial fibrillation (AF) is the most common and clinically significant type of cardiac arrhythmia. Although catheter ablation (CA) can restore sinus rhythm in patients with AF, some patients experience recurrence after the procedure. This requires us to find a simple and effective way to identify patients at a high risk of recurrence and to intervene early in the high-risk population to improve patient prognosis. The mechanism of AF recurrence is unclear, but it involves several aspects including patient history, inflammation, myocardial fibrosis, and genes. This article summarizes the current predictors of AF recurrence after CA, including myocardial fibrosis markers, inflammatory markers, MicroRNAs, Circular RNAs, AF recurrence scores, and imaging indicators. Each predictor has its own scope of application, and the predictive capacity and joint application of multiple predictors may improve the predictive power. In addition, we summarize the mechanisms involved in AF recurrence. We hope that this review will assist researchers understand the current predictors of AF recurrence and help them conduct further related studies.

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

Preoperative and postoperative administration of vitamin C in cardiac surgery patients - settings, dosages, duration, and clinical outcomes: a narrative review

Vitamin C or ascorbic acid is a water-soluble vitamin capable of directly donating electrons to reactive oxygen species, attenuating electrical remodeling, and cardiac dysfunction in patients undergoing cardiac surgery (CS), considered one of the most effective defenses against free radicals in the blood, thus being one of the first antioxidants consumed during oxidative stress. The aim of this review is to assess the effects of perioperative administration of vitamin C in CS patients. A comprehensive literature search was conducted in order to identify prospective cohort studies and/or randomized controlled trials reporting on the perioperative effects of vitamin C among adult patients undergoing CS. Studies published between January 1980 to December 2022 were included in our search, resulting in a total of 31 articles that met all our inclusion criteria. There seems to be a beneficial effect of vitamin C supplementation in arrhythmias such as in postoperative atrial fibrillation, reduction of ICU length of stay, and hospital length of stay, reduction in postoperative ventilation time, in inotropic demand, and in postoperative fatigue. Vitamin C can act as a scavenger of free radicals to decrease the peroxidation of the lipids present in the cell membrane, and to protect the myocardium postoperatively from ischemia/reperfusion injury, thus attenuating oxidative stress and inflammation. It represents a readily available and cost-effective strategy that could improve the outcome of patients undergoing CS, by reducing the risk of serious cardiovascular adverse events, both perioperatively and postoperatively.

Hereditary hemochromatosis with homozygous C282Y HFE mutation: possible clinical model to assess effects of elevated reactive oxygen species on the development of cardiovascular disease

Hereditary hemochromatosis with the homozygous C282Y HFE mutation (HH-282H) is a genetic condition which causes iron overload (IO) and elevated reactive oxygen species (ROS) secondary to the IO. Interestingly, even after successful iron removal therapy, HH-282H subjects demonstrate chronically elevated ROS. Raised ROS are also associated with the development of multiple cardiovascular diseases and HH-282H subjects may be at risk to develop these complications. In this narrative review, we consider HH-282H subjects as a clinical model for assessing the contribution of elevated ROS to the development of cardiovascular diseases in subjects with fewer confounding clinical risk factors as compared to other disease conditions with high ROS. We identify HH-282H subjects as a potentially unique clinical model to assess the impact of chronically elevated ROS on the development of cardiovascular disease and to serve as a clinical model to detect effective interventions for anti-ROS therapy.

Dapagliflozin attenuates the vulnerability to atrial fibrillation in rats with lipopolysaccharide-induced myocardial injury

BACKGROUND

Oxidative stress is an essential component participating in the development and maintenance of atrial fibrillation (AF). Dapagliflozin, a SGLT2 inhibitor, has been shown to exert cardioprotective effects by ameliorating oxidative stress in multiple heart disease models. However, its potential to attenuate lipopolysaccharide (LPS)-induced myocardial injury in rats remains unknown.

AIM

This study aims to investigate the role of dapagliflozin in LPS-induced myocardial injury and the potential mechanisms involved.

METHODS

Rats were intraperitoneally administered LPS to induce sepsis-like condition. The intervention was conducted with intraperitoneal injection of dapagliflozin or saline 1 h in advance. The effects of dapagliflozin were detected by electrophysiological recordings, western blot, qPCR, ELISA, HE staining, immunohistochemistry and fluorescence. We further validated the mechanism in vitro using HL-1 cells.

RESULTS

Dapagliflozin significantly improved LPS-induced myocardial injury, reduced susceptibility to AF, and mitigated atrial tissue inflammatory cell infiltration and atrial myocyte apoptosis. These were correlated with the Nrf2/HO-1 signaling pathway, which subsequently reduced oxidative stress. Subsequently, we used a specific inhibitor of the Nrf2/HO-1 pathway in vitro, reversed the anti-oxidative stress effects of dapagliflozin on HL-1 cells, further confirming the Nrf2/HO-1 pathway's pivotal role in dapagliflozin-mediated cardioprotection.

CONCLUSION

Dapagliflozin ameliorated myocardial injury and susceptibility to AF induced by LPS through anti-oxidative stress, which relied on upregulation of the Nrf2/HO-1 pathway.

Effect of PCSK9 Monoclonal Antibody Versus Placebo/Ezetimibe on Atrial Fibrillation in Patients at High Cardiovascular Risk: A Meta-Analysis of 26 Randomized Controlled Trials

BACKGROUND

Patients at high cardiovascular risk are closely associated with an increased risk of atrial fibrillation (AF). Whether proprotein convertase subtilisin/kexin type 9 monoclonal antibodies (PCSK9 mAbs) can attenuate AF progression remains unknown.

METHODS

To compare PCSK9 mAbs with placebo or ezetimibe to explore the effect of PCSK9 mAbs therapy on the end-point of incidence of AF, we searched PubMed, Embase, and ClinicalTrials.gov for articles. We used Mantel-Haenszel risk ratio (RR) with corresponding 95% CI for the categorical data, including the incidence of AF and predefined other outcomes of interest.

RESULTS

We included 21 articles consisting of 26 randomized controlled trials with a total of 95,635 participants. Quantitative synthesis revealed that PCSK9 mAbs significantly reduce the incidence of AF events (RR 0.84; 95% CI 0.72-0.98; p = 0.03), whereas no obvious differences were seen between the PCSK9 mAbs group and the ezetimibe group (RR 0.90; 95% CI 0.29-2.76; p = 0.85). PCSK9 mAbs also markedly decreased the incidence of cerebrovascular events (RR 0.75; 95% CI 0.66-0.85; p < 0.0001) and new-onset hypertension (RR 0.92; 95% CI 0.87-0.97; p = 0.003), but not the risk of cardiovascular death (RR 0.95; 95% CI 0.85-1.07; p = 0.40) and new-onset diabetes mellitus (RR 1.01; 95% CI 0.95-1.08; p = 0.67).

CONCLUSIONS

Overall, the PCSK9 mAbs therapy reduced AF and presented certain cardiovascular benefits in patients at high cardiovascular risk. Further big-scale and long follow-up duration randomized controlled trials that compare PCSK9 mAbs with ezetimibe are required to evaluate the effect of PCSK9 mAbs versus ezetimibe on AF.

Potential Role of Natural Antioxidants in Countering Reperfusion Injury in Acute Myocardial Infarction and Ischemic Stroke

Stroke and acute myocardial infarction are leading causes of mortality worldwide. The latter accounts for approximately 9 million deaths annually. In turn, ischemic stroke is a significant contributor to adult physical disability globally. While reperfusion is crucial for tissue recovery, it can paradoxically exacerbate damage through oxidative stress (OS), inflammation, and cell death. Therefore, it is imperative to explore diverse approaches aimed at minimizing ischemia/reperfusion injury to enhance clinical outcomes. OS primarily arises from an excessive generation of reactive oxygen species (ROS) and/or decreased endogenous antioxidant potential. Natural antioxidant compounds can counteract the injury mechanisms linked to ROS. While promising preclinical results, based on monotherapies, account for protective effects against tissue injury by ROS, translating these models into human applications has yielded controversial evidence. However, since the wide spectrum of antioxidants having diverse chemical characteristics offers varied biological actions on cell signaling pathways, multitherapy has emerged as a valuable therapeutic resource. Moreover, the combination of antioxidants in multitherapy holds significant potential for synergistic effects. This study was designed with the aim of providing an updated overview of natural antioxidants suitable for preventing myocardial and cerebral ischemia/reperfusion injuries.

Effect of Perioperative Oral Vitamin C Supplementation on In-Hospital Postoperative Medication Costs for Cardiac Surgery Patients: A Prospective, Single-Centre, Randomised Clinical Trial

BACKGROUND

Due to its antioxidant properties, vitamin C might be a promising and effective strategy for preventing postoperative atrial fibrillation (POAF) after cardiac surgery. This study was aimed at evaluating whether vitamin C supplementation is effective in reducing the cost of in-hospital postoperative medication used for patients undergoing coronary artery bypass (CABG) or valve surgery (±CABG).

OBJECTIVE

The primary goal of this study was to evaluate the impact of perioperative vitamin C supplementation in patients undergoing cardiac surgery on in-hospital postoperative medication costs, while secondary endpoints were the effects on length of stay (LOS) in both the intensive care unit (ICU) and the hospital, and the incidence of POAF.

MATERIAL AND METHODS

From November 2018 to January 2021, 253 patients planned for CABG or valve surgery (±CABG) in AZ Maria Middelares, Ghent, Belgium, and who met the inclusion criteria (≥18 years of age, all having cardiac sinus rhythm, and who provided written informed consent) were randomised into a placebo group or vitamin C group. The medication was administered orally (1 g twice daily), starting from 5 days preoperatively until 10 days postoperatively. The medication used, LOS in the hospital/ICU, and development of clinically relevant POAF in the ICU were registered.

RESULTS

Mean medication costs were €264.6 ± 98.1 for patients in the vitamin C group and €294.9 ± 267.3 for patients in the placebo group. When stratifying according to the type of surgery (CABG or valve surgery [±CABG]), these costs did not significantly differ. There was no significant difference in LOS or the incidence of clinically relevant POAF.

CONCLUSION

Our data did not identify any short-term financial impact on postoperative medication costs after oral perioperative vitamin C supplementation (1 g twice daily) for patients undergoing a CABG procedure or valve surgery (±CABG). No effect was found on the LOS or the incidence of clinically relevant POAF. Potential effects in the longer term, after intravenous administration of vitamin C or in other types of (cardiac) surgery, are still to be investigated.

CLINICAL TRIALS REGISTRATION NUMBER

NCT03592680.

Effects of Melatonin on Cardiac Injury and Inflammatory Biomarkers in Patients Undergoing Coronary Artery Bypass Graft Surgery: a Meta-analysis

INTRODUCTION

The antiinflammatory and antioxidative effects of melatonin have been established in recent years. Several studies indicate that oxidative stress and inflammation are key drivers of post-coronary artery bypass graft (CABG) surgery complications. In the present study, we aimed to investigate the effects of melatonin on cardiac injury and inflammatory biomarkers in CABG candidates.

METHODS

Embase, Medline/PubMed, Web of Science, Scopus, and the Cochrane library were searched up to 5 June 2022. All randomized controlled trials examining cardiac injury and inflammatory biomarkers of CABG patients who received melatonin were included. The random-effects model was utilized to perform the analysis.

RESULTS

A total of 947 citations were retrieved through database searches. Finally, five articles (six trials with 342 patients) were included after the screening. Melatonin supplementation led to a significant reduction in cardiac troponin I (CTnI) [weighted mean difference(WMD): -2.28 ng/ml; 95% CI -2.87, -1.69; P < 0.01; I²: 91.25%] and high sensitivity-C reactive protein (hs-CRP) levels (WMD: -0.62 mg/L; 95% CI -0.73, -0.5; P < 0.01; I²: 99.98%) in patients undergoing CABG surgery. We found a nonsignificant decrease in creatine kinase isoenzyme muscle/brain (CK-MB) levels (WMD: -2.87 ng/ml; 95% CI -5.97, 0.23; P = 0.07; I²: 99.98%) after melatonin supplementation. No publication bias was found according to Egger's test.

CONCLUSION

Melatonin supplementation may be useful in reducing cardiac injury and inflammatory biomarkers in CABG candidates. Future studies should investigate the clinical significance of these findings.

No causal association between tea consumption and 7 cardiovascular disorders: A two-sample Mendelian randomization study

Background: Previous studies have reported inconsistent results on the causal association between habitual tea consumption and the risk of cardiovascular disease (CVD). This study is aim to determine the association between habitual tea intake and CVD using two-sample Mendelian randomization (MR) analysis. Methods: The genetically predicted causation between tea consumption and 7 common cardiovascular diseases (atrial fibrillation, hypertension, acute myocardial infarction, coronary atherosclerosis, peripheral vascular disease, angina, and heart failure) was evaluated using MR analysis model. We performed a total of 9 MR analysis methods to analyze the final results. The IVW methods was used as the primary outcome. The other MR analysis method (simple mode, weighted mode, simple median, weighted median, penalized weighted median, MR Egger, and MR-Egger (bootstrap)) were performed as the complement to IVW. Also, the robustness of the MR analysis results was assessed using a leave-one-out analysis. Results: The IVW analysis methods indicated that there is no causal association between tea consumption and risk of CVD (AF: OR, 0.997, 95% CI, 0.992-1.0001, p = 0.142; hypertension: OR, 0.976, 95% CI, 0.937-1.017, p = 0.242; AMI: OR, 0.996, 95% CI, 0.991-1.000, p = 0.077; CA: OR, 1.001, 95% CI, 0.993-1.009, p = 0.854; PVD: OR, 1.002, 95% CI, 1.000-1.005, p = 0.096; angina: OR, 0.999, 95% CI, 0.993-1.006, p = 0.818; HF: OR, 0.999, 95% CI, 0.996-1.002, p = 0.338). The other MR analysis method and further leave-one-out sensitivity analysis suggested the results were robust. Conclusion: This MR study indicated that there was no genetically predicted causal association between habitual tea intake and risk of CVD.

Biodegradable Redox-Responsive AIEgen-Based-Covalent Organic Framework Nanocarriers for Long-Term Treatment of Myocardial Ischemia/Reperfusion Injury

Timely restoration of blood supply after myocardial ischemia is imperative for the treatment of acute myocardial infarction but causes additional myocardial ischemia/reperfusion (MI/R) injury, which has not been hitherto effectively targeted by interventions for MI/R injury. Hence, the development of advanced nanomedicine that can reduce apoptosis of cardiomyocytes while protecting against MI/R in vivo is of utmost importance. Herein, a redox-responsive and emissive TPE-ss covalent organic framework (COF) nanocarrier by integrating aggregation-induced emission luminogens and redox-responsive disulfide motifs into the COF skeleton is developed. TPE-ss COF allows for efficient loading and delivery of matrine, a renowned anti-cryptosporidial drug, which significantly reduces MI/R-induced functional deterioration and cardiomyocyte injury when injected through the tail vein into MI/R models at 5 min after 30 min of ischemia. Moreover, TPE-ss COF@Matrine shows a drastic reduction in cardiomyocyte apoptosis and improvements in cardiac function and survival rate. The effect of the TPE-ss COF carrier is further elucidated by enhanced cardiomyocyte viability and triphenyltetrazolium chloride staining in vitro. This work demonstrates the cardioprotective effect of TPE-ss COFs for MI/R injury, which unleashes the immense potential of using COFs as smart drug carriers for the peri-reperfusion treatment of ischemic heart disease with low cost, high stability, and single postoperative intervention.

Dose-dependent scavenging activity of the ultra-short-acting β1-blocker landiolol against specific free radicals

Landiolol, a highly cardioselective ultra-short-acting β1-blocker, prevents perioperative atrial fibrillation associated with systemic inflammation and oxidative stress. We evaluated the direct scavenging activity of landiolol against multiple free radical species. Nine free radical species (hydroxyl, superoxide anion, ascorbyl, tert-butyl peroxyl, tert-butoxyl, singlet oxygen, 2,2-diphenyl-1-picrylhydrazyl, nitric oxide, and tyrosyl radicals) were directly quantified using an X-band ESR spectrometer with the spin-trapping method. IC50 and reaction rate constants were estimated from the dose-response curve for each free radical. Landiolol scavenged six of the free radical species examined: hydroxyl radical (IC50 = 0.76 mM, k landiolol = 1.4 × 10‍10 M‍-1 s‍-1, p<0.001), superoxide anion (58 mM, 2.1 M‍-1 s‍-1, p = 0.044), tert-butoxyl radical (4.3 mM, k landiolol/k CYPMPO = 0.77, p<0.001), ascorbyl free radical (0.31 mM, p<0.001), singlet oxygen (0.69 mM, k landiolol/k 4-OH ‍TEMP = 2.9, p<0.001), and nitric oxide (15 mM, 1.7 × 10 M‍-1 s‍-1, p<0.001). This study is the first to report that landiolol dose-dependently scavenges multiple free radical species with different reaction rate constants. These results indicate the potential clinical application of landiolol as an antioxidative and anti-inflammatory agent in addition to its present clinical use as an anti-arrhythmic agent.

Antioxidants in Arrhythmia Treatment—Still a Controversy? A Review of Selected Clinical and Laboratory Research

Antioxidants are substances that can prevent damage to cells caused by free radicals. Production of reactive oxygen species and the presence of oxidative stress play an important role in cardiac arrhythmias. Currently used antiarrhythmic drugs have many side effects. The research on animals and humans using antioxidants (such as vitamins C and E, resveratrol and synthetic substances) yields many interesting but inconclusive results. Natural antioxidants, such as vitamins C and E, can reduce the recurrence of atrial fibrillation (AF) after successful electrical cardioversion and protect against AF after cardiac surgery, but do not affect the incidence of atrial arrhythmias in critically ill patients with trauma. Vitamins C and E may also effectively treat ventricular tachycardia, ventricular fibrillation and long QT-related arrhythmias. Another natural antioxidant—resveratrol—may effectively treat AF and ventricular arrhythmias caused by ischaemia–reperfusion injury. It reduces the mortality associated with life-threatening ventricular arrhythmias and can be used to prevent myocardial remodelling. Statins also show antioxidant activity. Their action is related to the reduction of oxidative stress and anti-inflammatory effect. Therefore, statins can reduce the post-operative risk of AF and may be useful in lowering its recurrence rate after successful cardioversion. Promising results also apply to polyphenols, nitric oxide synthase inhibitors and MitoTEMPO. Although few clinical trials have been conducted, the use of antioxidants in treating arrhythmias is an interesting prospect.

Amiodarone with or without N-Acetylcysteine for the Prevention of Atrial Fibrillation after Thoracic Surgery: A Double-blind, Randomized Trial

BACKGROUND

Postoperative atrial fibrillation may identify patients at risk of subsequent atrial fibrillation, with its greater risk of stroke. This study hypothesized that N-acetylcysteine mitigates inflammation and oxidative stress to reduce the incidence of postoperative atrial fibrillation.

METHODS

In this double-blind, placebo-controlled trial, patients at high risk of postoperative atrial fibrillation scheduled to undergo major thoracic surgery were randomized to N-acetylcysteine plus amiodarone or placebo plus amiodarone. On arrival to the postanesthesia care unit, N-acetylcysteine or placebo intravenous bolus (50 mg/kg) and then continuous infusion (100 mg/kg over the course of 48 h) was administered plus intravenous amiodarone (bolus of 150 mg and then continuous infusion of 2 g over the course of 48 h). The primary outcome was sustained atrial fibrillation longer than 30 s by telemetry (first 72 h) or symptoms requiring intervention and confirmed by electrocardiography within 7 days of surgery. Systemic markers of inflammation (interleukin-6, interleukin-8, tumor necrosis factor α, C-reactive protein) and oxidative stress (F2-isoprostane prostaglandin F2α; isofuran) were assessed immediately after surgery and on postoperative day 2. Patients were telephoned monthly to assess the occurrence of atrial fibrillation in the first year.

RESULTS

Among 154 patients included, postoperative atrial fibrillation occurred in 15 of 78 who received N-acetylcysteine (19%) and 13 of 76 who received placebo (17%; odds ratio, 1.24; 95.1% CI, 0.53 to 2.88; P = 0.615). The trial was stopped at the interim analysis because of futility. Of the 28 patients with postoperative atrial fibrillation, 3 (11%) were discharged in atrial fibrillation. Regardless of treatment at 1 yr, 7 of 28 patients with postoperative atrial fibrillation (25%) had recurrent episodes of atrial fibrillation. Inflammatory and oxidative stress markers were similar between groups.

CONCLUSIONS

Dual therapy comprising N-acetylcysteine plus amiodarone did not reduce the incidence of postoperative atrial fibrillation or markers of inflammation and oxidative stress early after major thoracic surgery, compared with amiodarone alone. Recurrent atrial fibrillation episodes are common among patients with postoperative atrial fibrillation within 1 yr of major thoracic surgery.

EDITOR’S PERSPECTIVE

Atrial nitroso-redox balance and refractoriness following on-pump cardiac surgery: a randomized trial of atorvastatin

AIMS

Systemic inflammation and increased activity of atrial NOX2-containing NADPH oxidases have been associated with the new onset of atrial fibrillation (AF) after cardiac surgery. In addition to lowering LDL-cholesterol, statins exert rapid anti-inflammatory and antioxidant effects, the clinical significance of which remains controversial.

METHODS AND RESULTS

We first assessed the impact of cardiac surgery and cardiopulmonary bypass (CPB) on atrial nitroso-redox balance by measuring NO synthase (NOS) and GTP cyclohydrolase-1 (GCH-1) activity, biopterin content, and superoxide production in paired samples of the right atrial appendage obtained before (PRE) and after CPB and reperfusion (POST) in 116 patients. The effect of perioperative treatment with atorvastatin (80 mg once daily) on these parameters, blood biomarkers, and the post-operative atrial effective refractory period (AERP) was then evaluated in a randomized, double-blind, placebo-controlled study in 80 patients undergoing cardiac surgery on CPB. CPB and reperfusion led to a significant increase in atrial superoxide production (74% CI 71-76%, n = 46 paired samples, P < 0.0001) and a reduction in atrial tetrahydrobiopterin (BH4) (34% CI 33-35%, n = 36 paired samples, P < 0.01), and in GCH-1 (56% CI 55-58%, n = 26 paired samples, P < 0.001) and NOS activity (58% CI 52-67%, n = 20 paired samples, P < 0.001). Perioperative atorvastatin treatment prevented the effect of CPB and reperfusion on all parameters but had no significant effect on the postoperative right AERP, troponin release, or NT-proBNP after cardiac surgery.

CONCLUSION

Perioperative statin therapy prevents post-reperfusion atrial nitroso-redox imbalance in patients undergoing on-pump cardiac surgery but has no significant impact on postoperative atrial refractoriness, perioperative myocardial injury, or markers of postoperative LV function.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT01780740.

Contribution of oxidative stress in the mechanisms of postoperative complications and multiple organ dysfunction syndrome

BACKGROUND

The extent of the damage following surgery has been subject of study for several years. Numerous surgical complications can impact postoperative quality of life of patients and even can cause mortality. Although these complications are generally due to multifactorial mechanisms, oxidative stress plays a key pathophysiological role. Moreover, oxidative stress could be an unavoidable effect derived even from the surgical procedure itself.

METHODS

A systematic review was performed following an electronic search of Pubmed and ScienceDirect databases. Keywords such as sepsis, oxidative stress, organ dysfunction, antioxidants, outcomes in postoperative complications, among others, were used. Review articles were preferably used between the years 2015 onwards, not excluding older ones.

RESULTS

The vast majority point to the role of oxidative stress in generating greater damage and worse prognosis in postoperative patients without the necessary care and precautions, taking importance on the use of antioxidants to prevent this problem.

DISCUSSIONS

Oxidative stress represents a common final pathway related to pathological processes such as inflammation or ischemia-reperfusion, among others. The expression of greater severity of these complications can result in multiple organ dysfunction or sepsis. The aim of this study was to present an update of the role of oxidative stress on surgical postoperative complications.

A double-blind randomised controlled trial on the effect of Tocovid, a tocotrienol-rich capsule on postoperative atrial fibrillation at the National Heart Institute, Kuala Lumpur: an interim blinded analysis

INTRODUCTION

Post-operative atrial fibrillation (POAF) is associated with poorer outcomes, increased resource utilisation, morbidity and mortality. Its pathogenesis is initiated by systemic inflammation and oxidative stress. It is hypothesised that a potent antioxidant and anti-inflammatory agent such as tocotrienol, an isomer of Vitamin E, could reduce or prevent POAF.

AIMS

The aim of this study is to determine whether a potent antioxidative and anti-inflammatory agent, Tocovid, a tocotrienol-rich capsule, could reduce the incidence of POAF and affect the mortality and morbidity as well as the duration of ICU, HDU and hospital stay.

METHODS

This study was planned as a prospective, randomised, controlled trial with parallel groups. The control group received placebo containing palm superolein while the treatment group received Tocovid capsules. We investigated the incidence of POAF, the length of hospital stay after surgery and the health-related quality of life.

RESULTS

Recruitment commenced in January 2019 but the preliminary results were unblinded as the study is still ongoing. Two-hundred and two patients have been recruited out of a target sample size of 250 as of January 2021. About 75% have completed the study and 6.4% were either lost during follow-up or withdrew; 4% of participants died. The mean age group was 61.44 ± 7.30 years with no statistical difference between the groups, with males having a preponderance for AF. The incidence of POAF was 24.36% and the mean time for developing POAF was 55.38 ± 29.9 h post-CABG. Obesity was not a predictive factor. No statistically significant difference was observed when comparing left atrial size, NYHA class, ejection fraction and the premorbid history. The mean cross-clamp time was 71 ± 34 min and the mean bypass time was 95 ± 46 min, with no difference between groups. There was a threefold increase in death among patients with POAF (p = 0.008) and an increase in the duration of ICU stay (p = 0.01), the total duration of hospital stay (p = 0.04) and reintubation (p = 0.045).

CONCLUSION

A relatively low incidence rate of POAF was noted although the study is still ongoing. It remains to be seen if our prophylactic intervention using Tocovid would effectively reduce the incidence of POAF. Clinical Registration Number: US National Library of Medicine. Clinical Trials - NCT03807037. Registered on 16th January 2019. Link: https://clinicaltrials.gov/ct2/show/NCT03807037.

Combating Ischemia-Reperfusion Injury with Micronutrients and Natural Compounds during Solid Organ Transplantation: Data of Clinical Trials and Lessons of Preclinical Findings

Although extended donor criteria grafts bear a higher risk of complications such as graft dysfunction, the exceeding demand requires to extent the pool of potential donors. The risk of complications is highly associated with ischemia-reperfusion injury, a condition characterized by high loads of oxidative stress exceeding antioxidative defense mechanisms. The antioxidative properties, along with other beneficial effects like anti-inflammatory, antiapoptotic or antiarrhythmic effects of several micronutrients and natural compounds, have recently emerged increasing research interest resulting in various preclinical and clinical studies. Preclinical studies reported about ameliorated oxidative stress and inflammatory status, resulting in improved graft survival. Although the majority of clinical studies confirmed these results, reporting about improved recovery and superior organ function, others failed to do so. Yet, only a limited number of micronutrients and natural compounds have been investigated in a (large) clinical trial. Despite some ambiguous clinical results and modest clinical data availability, the vast majority of convincing animal and in vitro data, along with low cost and easy availability, encourage the conductance of future clinical trials. These should implement insights gained from animal data.

Synergistic Action of Membrane-Bound and Water-Soluble Antioxidants in Neuroprotection

Prevention of neurodegeneration during aging, and support of optimal brain function throughout the lifespan, requires protection of membrane structure and function. We review the synergistic action of different classes of dietary micronutrients, as well as further synergistic contributions from exercise and stress reduction, in supporting membrane structure and function. We address membrane-associated inflammation involving reactive oxygen species (ROS) that produce immune regulators from polyunsaturated fatty acids (PUFAs) of membrane phospholipids. The potential of dietary micronutrients to maintain membrane fluidity and prevent chronic inflammation is examined with a focus on synergistically acting membrane-soluble components (zeaxanthin, lutein, vitamin E, and omega-3 PUFAs) and water-soluble components (vitamin C and various phenolics). These different classes of micronutrients apparently operate in a series of intertwined oxidation-reduction cycles to protect membrane function and prevent chronic inflammation. At this time, it appears that combinations of a balanced diet with regular moderate exercise and stress-reduction practices are particularly beneficial. Effective whole-food-based diets include the Mediterranean and the MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay diet, where DASH stands for Dietary Approaches to Stop Hypertension).

Novel Combined Antioxidant Strategy against Hypertension, Acute Myocardial Infarction and Postoperative Atrial Fibrillation

Reactive oxygen species (ROS) play a physiological role in the modulation of several functions of the vascular wall; however, increased ROS have detrimental effects. Hence, oxidative stress has pathophysiological impacts on the control of the vascular tone and cardiac functions. Recent experimental studies reported the involvement of increased ROS in the mechanism of hypertension, as this disorder associates with increased production of pro-oxidants and decreased bioavailability of antioxidants. In addition, increased ROS exposure is found in ischemia-reperfusion, occurring in acute myocardial infarction and cardiac surgery with extracorporeal circulation, among other settings. Although these effects cause major heart damage, at present, there is no available treatment. Therefore, it should be expected that antioxidants counteract the oxidative processes, thereby being suitable against cardiovascular disease. Nevertheless, although numerous experimental studies agree with this notion, interventional trials have provided mixed results. A better knowledge of ROS modulation and their specific interaction with the molecular targets should contribute to the development of novel multitarget antioxidant effective therapeutic strategies. The complex multifactorial nature of hypertension, acute myocardial infarction, and postoperative atrial fibrillation needs a multitarget antioxidant strategy, which may give rise to additive or synergic protective effects to achieve optimal cardioprotection.

Antioxidant treatment to reduce mortality and serious adverse events in adult surgical patients: A systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Hyperoxia during anesthesia can increase cellular oxidative stress, and perioperative antioxidant treatment may reduce the resulting damage. The aim of this review was to evaluate risks and benefits of antioxidant treatment in surgical patients. We hypothesized that antioxidant treatment reduced mortality compared to placebo/no intervention.

METHODS

This systematic review with meta-analyses and trial sequential analysis (TSA) was conducted using Cochrane standards and GRADE methodology. Randomized clinical trials comparing perioperative antioxidant treatment vs. placebo/no intervention in adults were included. Primary outcome was mortality at longest follow-up.

RESULTS

Ninety-seven trials with 8156 patients were included. The most common interventions were N-Acetylcysteine (36 trials) and vitamin C (29 trials). Trials were primarily performed during cardiac surgery (53 trials). Fifty-six trials with 4890 patients reported information on mortality (243 events). The meta-analysis of mortality at longest follow-up showed a reduced mortality in antioxidant treated patients (RR 0.74, 95% CI 0.59; 0.94, I2 0%), however, TSA-adjusted CI was broadened (0.55-1.02) and only 31% of the required information size was reached. Furthermore, in the subgroup of three trials with overall low risk of bias the RR for mortality was 1.18 (95% CI 0.39, 3.63). Based on GRADE, our findings are of low quality of evidence due to high risk of bias, imprecision, and indirectness.

CONCLUSION

We found a 26% relative risk reduction of mortality in surgical patients treated with antioxidants but the quality of evidence supporting our findings is low and influenced by clinical heterogeneity and high risk of systematic- and random errors.

Long-term outcomes of postoperative atrial fibrillation following non cardiac surgery: A systematic review and metanalysis

BACKGROUND

New-onset atrial fibrillation (AF) in non-cardiac postoperative setting is common and is associated with a high risk of in-hospital mortality and morbidity. The long-term risks of stroke, mortality and AF recurrence rate in patients with postoperative AF (POAF) are unclear.

METHODS

We performed a systematic literature review in electronic databases from inception to March 5th, 2020 of studies reporting the incidence of stroke, mortality and AF recurrence in patients with POAF. We confined our analysis to studies with a cohort of at least 150 patients with POAF and with a median follow-up of 12 months as a minimum. Odds Ratios (OR) were pooled using a random-effects model.

RESULTS

Qualitative analysis included 8 studies (7 observational cohort studies and 1 randomized controlled trial) enrolling 3,718,587 patients. Six studies underwent metanalysis comprising 17,684 postoperative patients with POAF and 2,169,248 postoperative patients without POAF. The development of POAF conferred a four-fold increased risk of stroke in the long-term [OR 4.05; 95% confidence interval (CI) 2.91-5.62]. Mortality in the two studies reporting long-term data was higher in patients with POAF compared to those without POAF (OR 3.59; CI 95% 2.84-4.53). Data about recurrence were too heterogeneous to undergo metanalysis.

CONCLUSIONS

POAF is associated with a greater risk of stroke and mortality over the long-term period. Studies focusing on AF recurrence are needed to address the perception of POAF as a benign transient entity. The increased mortality risk following POAF should encourage systematic detection and prevention of this arrhythmia.

Cardiovascular Impact of Nutritional Supplementation With Omega-3 Fatty Acids: JACC Focus Seminar

Omega-3 polyunsaturated fatty acids (PUFAs) are a key component of a heart-healthy diet. For patients without clinical atherosclerotic cardiovascular disease, 2 or more servings of fatty fish per week is recommended to obtain adequate intake of omega-3 PUFAs. If this not possible, dietary supplementation with an appropriate fish oil may be reasonable. Supplementation with omega-3 PUFA capsules serves 2 distinct but overlapping roles: treatment of hypertriglyceridemia and prevention of cardiovascular events. Marine-derived omega-3 PUFAs reduce triglycerides and have pleiotropic effects including decreasing inflammation, improving plaque composition and stability, and altering cellular membranes. Clinical trial data have shown inconsistent results with omega-3 PUFAs improving cardiovascular outcomes. In this paper, the authors provide an overview of PUFAs and a summary of key clinical trial data. Recent trial data suggest the use of prescription eicosapentaenoic acid ethyl ester for atherosclerotic cardiovascular disease event reduction in selected populations.

Mitochondrial and Sarcoplasmic Reticulum Interconnection in Cardiac Arrhythmia

Ca²⁺ plays a pivotal role in mitochondrial energy production, contraction, and apoptosis. Mitochondrial Ca²⁺-targeted fluorescent probes have demonstrated that mitochondria Ca²⁺ transients are synchronized with Ca²⁺ fluxes occurring in the sarcoplasmic reticulum (SR). The presence of specialized proteins tethering SR to mitochondria ensures the local Ca²⁺ flux between these organelles. Furthermore, communication between SR and mitochondria impacts their functionality in a bidirectional manner. Mitochondrial Ca²⁺ uptake through the mitochondrial Ca²⁺ uniplex is essential for ATP production and controlled reactive oxygen species levels for proper cellular signaling. Conversely, mitochondrial ATP ensures the proper functioning of SR Ca²⁺-handling proteins, which ensures that mitochondria receive an adequate supply of Ca²⁺. Recent evidence suggests that altered SR Ca²⁺ proteins, such as ryanodine receptors and the sarco/endoplasmic reticulum Ca²⁺ ATPase pump, play an important role in maintaining proper cardiac membrane excitability, which may be initiated and potentiated when mitochondria are dysfunctional. This recognized mitochondrial role offers the opportunity to develop new therapeutic approaches aimed at preventing cardiac arrhythmias in cardiac disease.

Role of Oxidative Stress in the Mechanisms of Anthracycline-Induced Cardiotoxicity: Effects of Preventive Strategies

Anthracycline-induced cardiotoxicity (AIC) persists as a significant cause of morbidity and mortality in cancer survivors. Although many protective strategies have been evaluated, cardiotoxicity remains an ongoing threat. The mechanisms of AIC remain unclear; however, several pathways have been proposed, suggesting a multifactorial origin. When the central role of topoisomerase 2β in the pathophysiology of AIC was described some years ago, the classical reactive oxygen species (ROS) hypothesis shifted to a secondary position. However, new insights have reemphasized the importance of the role of oxidative stress-mediated signaling as a common pathway and a critical modulator of the different mechanisms involved in AIC. A better understanding of the mechanisms of cardiotoxicity is crucial for the development of treatment strategies. It has been suggested that the available therapeutic interventions for AIC could act on the modulation of oxidative balance, leading to a reduction in oxidative stress injury. These indirect antioxidant effects make them an option for the primary prevention of AIC. In this review, our objective is to provide an update of the accumulated knowledge on the role of oxidative stress in AIC and the modulation of the redox balance by potential preventive strategies.

A Remote Nutritional Intervention to Change the Dietary Habits of Patients Undergoing Ablation of Atrial Fibrillation: Randomized Controlled Trial

BACKGROUND

The Prevention With Mediterranean Diet (PREDIMED) trial supported the effectiveness of a nutritional intervention conducted by a dietitian to prevent cardiovascular disease. However, the effect of a remote intervention to follow the Mediterranean diet has been less explored.

OBJECTIVE

This study aims to assess the effectiveness of a remotely provided Mediterranean diet-based nutritional intervention in obtaining favorable dietary changes in the context of a secondary prevention trial of atrial fibrillation (AF).

METHODS

The PREvention of recurrent arrhythmias with Mediterranean diet (PREDIMAR) study is a 2-year multicenter, randomized, controlled, single-blinded trial to assess the effect of the Mediterranean diet enriched with extra virgin olive oil (EVOO) on the prevention of atrial tachyarrhythmia recurrence after catheter ablation. Participants in sinus rhythm after ablation were randomly assigned to an intervention group (Mediterranean diet enriched with EVOO) or a control group (usual clinical care). The remote nutritional intervention included phone contacts (1 per 3 months) and web-based interventions with provision of dietary recommendations, and participants had access to a web page, a mobile app, and printed resources. The information is divided into 6 areas: Recommended foods, Menus, News and Online resources, Practical tips, Mediterranean diet classroom, and Your personal experience. At baseline and at 1-year and 2-year follow-up, the 14-item Mediterranean Diet Adherence Screener (MEDAS) questionnaire and a semiquantitative food frequency questionnaire were collected by a dietitian by phone.

RESULTS

A total of 720 subjects were randomized (365 to the intervention group, 355 to the control group). Up to September 2020, 560 subjects completed the first year (560/574, retention rate 95.6%) and 304 completed the second year (304/322, retention rate 94.4%) of the intervention. After 24 months of follow-up, increased adherence to the Mediterranean diet was observed in both groups, but the improvement was significantly higher in the intervention group than in the control group (net between-group difference: 1.8 points in the MEDAS questionnaire (95% CI 1.4-2.2; P<.001). Compared with the control group, the Mediterranean diet intervention group showed a significant increase in the consumption of fruits (P<.001), olive oil (P<.001), whole grain cereals (P=.002), pulses (P<.001), nuts (P<.001), white fish (P<.001), fatty fish (P<.001), and white meat (P=.007), and a significant reduction in refined cereals (P<.001), red and processed meat (P<.001), and sweets (P<.001) at 2 years of intervention. In terms of nutrients, the intervention group significantly increased their intake of omega-3 (P<.001) and fiber (P<.001), and they decreased their intake of carbohydrates (P=.02) and saturated fatty acids (P<.001) compared with the control group.

CONCLUSIONS

The remote nutritional intervention using a website and phone calls seems to be effective in increasing adherence to the Mediterranean diet pattern among AF patients treated with catheter ablation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03053843; https://www.clinicaltrials.gov/ct2/show/NCT03053843.

Flavonoid intake and its association with atrial fibrillation

BACKGROUND & AIMS

Primary prevention of atrial fibrillation (AF) through behavioural and dietary modification is a critically important and unmet need. Flavonoids are bioactive dietary compounds with promising cardiovascular health benefits. Our aim was to investigate the association between flavonoid intake and clinically apparent AF.

METHODS

Baseline data from 55 613 participants of the Danish Diet, Cancer and Health Study, without AF, recruited between 1993 and 1997, were cross-linked with Danish nationwide registries. Total flavonoid and flavonoid subclass intakes were calculated from validated food frequency questionnaires using the Phenol-Explorer database. Associations between flavonoid intake and incident AF (first-time hospitalization or outpatient visit) were examined using restricted cubic splines based on Cox proportional hazards models.

RESULTS

During a median [IQR] follow-up of 21 [18-22] years, 7291 participants were diagnosed with AF. Total flavonoid intake was not statistically significantly associated with risk of incident AF in the whole cohort. However, compared to the lowest quintile, a total flavonoid intake of 1000 mg/day was associated with a lower risk of AF in smokers [0.86 (0.77, 0.96)] but not in non-smokers [0.96 (0.88, 1.06)], and a lower risk of AF in high alcohol consumers [>20 g/d: 0.84 (0.75, 0.95)] but not in low-to-moderate alcohol consumers [<20 g/d: 0.97 (0.89, 1.07)].

CONCLUSION

Intake of flavonoids was not significantly associated with a lower risk of incident AF. However, higher intakes of flavonoids may be beneficial for those at a higher risk of developing AF.

Potential use of n-3 PUFAs to prevent oxidative stress-derived ototoxicity caused by platinum-based chemotherapy

Platinum-based compounds are widely used for the treatment of different malignancies due to their high effectiveness. Unfortunately, platinum-based treatment may lead to ototoxicity, an often-irreversible side effect without a known effective treatment and prevention plan. Platinum-based compound-related ototoxicity results mainly from the production of toxic levels of reactive oxygen species (ROS) rather than DNA-adduct formation, which has led to test strategies based on direct ROS scavengers to ameliorate hearing loss. However, favorable clinical results have been associated with several complications, including potential interactions with chemotherapy efficacy. To understand the contribution of the different cytotoxic mechanisms of platinum analogues on malignant cells and auditory cells, the particular susceptibility and response of both kinds of cells to molecules that potentially interfere with these mechanisms, is fundamental to develop innovative strategies to prevent ototoxicity without affecting antineoplastic effects. The n-3 long-chain polyunsaturated fatty acids (n-3 PUFAs) have been tried in different clinical settings, including with cancer patients. Nevertheless, their use to decrease cisplatin-induced ototoxicity has not been explored to date. In this hypothesis paper, we address the mechanisms of platinum compounds-derived ototoxicity, focusing on the differences between the effects of these compounds in neoplastic versus auditory cells. We discuss the basis for a strategic use of n-3 PUFAs to potentially protect auditory cells from platinum-derived injury without affecting neoplastic cells and chemotherapy efficacy.

Mechanisms of Chronic Metabolic Stress in Arrhythmias

Cardiac arrhythmias are responsible for many cardiovascular disease-related deaths worldwide. While arrhythmia pathogenesis is complex, there is increasing evidence for metabolic causes. Obesity, diabetes, and chronically consuming high-fat foods significantly increase the likelihood of developing arrhythmias. Although these correlations are well established, mechanistic explanations connecting a high-fat diet (HFD) to arrhythmogenesis are incomplete, although oxidative stress appears to be critical. This review investigates the metabolic changes that occur in obesity and after HFD. Potential therapies to prevent or treat arrhythmias are discussed, including antioxidants.

The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

Redox control of vascular biology

Redox control is lost when the antioxidant defense system cannot remove abnormally high concentrations of signaling molecules, such as reactive oxygen species (ROS). Chronically elevated levels of ROS cause oxidative stress that may eventually lead to cancer and cardiovascular and neurodegenerative diseases. In this review, we focus on redox effects in the vascular system. We pay close attention to the subcompartments of the vascular system (endothelium, smooth muscle cell layer) and give an overview of how redox changes influence those different compartments. We also review the core aspects of redox biology, cardiovascular physiology, and pathophysiology. Moreover, the topic-specific knowledgebase DES-RedoxVasc was used to develop two case studies, one focused on endothelial cells and the other on the vascular smooth muscle cells, as a starting point to possibly extend our knowledge of redox control in vascular biology.

Prevention of doxorubicin-induced Cardiotoxicity by pharmacological non-hypoxic myocardial preconditioning based on Docosahexaenoic Acid (DHA) and carvedilol direct antioxidant effects: study protocol for a pilot, randomized, double-blind, controlled trial (CarDHA trial)

BACKGROUND

Anthracycline-induced cardiotoxicity (AIC), a condition associated with multiple mechanisms of damage, including oxidative stress, has been associated with poor clinical outcomes. Carvedilol, a β-blocker with unique antioxidant properties, emerged as a strategy to prevent AIC, but recent trials question its effectiveness. Some evidence suggests that the antioxidant, not the β-blocker effect, could prevent related cardiotoxicity. However, carvedilol's antioxidant effects are probably not enough to prevent cardiotoxicity manifestations in certain cases. We hypothesize that breast cancer patients taking carvedilol as well as a non-hypoxic myocardial preconditioning based on docosahexaenoic acid (DHA), an enhancer of cardiac endogenous antioxidant capacity, will develop less subclinical cardiotoxicity manifestations than patients randomized to double placebo.

METHODS/DESIGN

We designed a pilot, randomized controlled, two-arm clinical trial with 32 patients to evaluate the effects of non-hypoxic cardiac preconditioning (DHA) plus carvedilol on subclinical cardiotoxicity in breast cancer patients undergoing anthracycline treatment. The trial includes four co-primary endpoints: changes in left ventricular ejection fraction (LVEF) determined by cardiac magnetic resonance (CMR); changes in global longitudinal strain (GLS) determined by two-dimensional echocardiography (ECHO); elevation in serum biomarkers (hs-cTnT and NT-ProBNP); and one electrocardiographic variable (QTc interval). Secondary endpoints include other imaging, biomarkers and the occurrence of major adverse cardiac events during follow-up. The enrollment and follow-up for clinical outcomes is ongoing.

DISCUSSION

We expect a group of anthracycline-treated breast cancer patients exposed to carvedilol and non-hypoxic myocardial preconditioning with DHA to show less subclinical cardiotoxicity manifestations than a comparable group exposed to placebo.

TRIAL REGISTRATION

ISRCTN registry, ID: ISRCTN69560410. Registered on 8 June 2016.

PREvention of recurrent arrhythmias with Mediterranean diet (PREDIMAR) study in patients with atrial fibrillation: Rationale, design and methods

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Catheter ablation aims to restore sinus rhythm. However, relapses occur in up to 30% of patients. A Mediterranean diet (MedDiet) enriched with extra-virgin olive oil (EVOO) substantially reduced the incidence of AF in the PREDIMED trial. The PREDIMAR will test a similar intervention in secondary prevention.

Methods

PREDIMAR is a multicenter, randomized, single-blind trial testing the effect of a MedDiet enriched with EVOO to reduce tachyarrhythmia relapses after AF ablation. The primary outcome is the recurrence of any sustained atrial tachyarrhythmia after ablation (excluding those occurring only during the first 3 months after ablation). The target final sample size is 720 patients (360 per group) recruited from 4 Spanish hospitals. A remote intervention, maintained for 2 years, is delivered to the active intervention group including periodic phone calls by a dietitian and free provision of EVOO. The control group will receive delayed intervention after trial completion. Routine electrocardiogram (ECG) and Holter ECG are performed, and a portable cardiac rhythm monitoring device is provided to be worn by participants during 15 months.

Results

Recruitment started in March 2017. Up to July 2019, 609 patients were randomized (average inclusion rate: 5.3 patients/wk). Retention rates after 18 months are >94%.

Conclusions

If our hypothesis is confirmed, the utility of the MedDiet enriched with EVOO in slowing the progression of AF will be proven, preventing recurrences and potentially reducing complications.

Postoperative Atrial Fibrillation Following Cardiac Surgery: From Pathogenesis to Potential Therapies

Postoperative atrial fibrillation (POAF) is a major complication after cardiac surgery which can lead to high rates of morbidity and mortality, an enhanced length of hospital stay, and an increased cost of care. POAF is postulated to be a multifactorial phenomenon; however, some major pathogeneses have been proposed, including inflammatory pathways, oxidative stress, and autonomic dysfunction. Genetic studies also showed that inflammatory pathways, beta-1 adrenoreceptor variants, G protein-coupled receptor kinase 5 gene variants, and non-coding single-nucleotide polymorphisms in the 4q25 chromosomal locus are involved in this phenomenon. Moreover, several predisposing factors lead to the development of POAF, consisting of pre-, intra-, and postoperative contributors. The main predisposing factors comprise age, prior history of major cardiovascular risk factors, and ischemia-reperfusion injury during surgery. The management of POAF is based on the usual therapies used for non-surgical AF, including medications for either rate control or rhythm control in hemodynamically unstable patients. The perioperative administration of β-blockers and some antiarrhythmic agents has been recommended in major international guidelines. In addition, upstream therapies consisting of colchicine, magnesium, statins, and antioxidants have attenuated the incidence of POAF; however, some uncomfortable side effects developed in large randomized trials. The use of anticoagulation has also resulted in less mortality in patients with POAF at higher risk of thromboembolic events. Despite these recommendations, the actual regimen for the prevention of POAF remains controversial. In this review, we highlight the pathogenesis, predisposing factors, and potential therapeutic options for the management of patients at risk for or with POAF following cardiac surgery.

Early Oxidative Stress Response in Patients with Severe Aortic Stenosis Undergoing Transcatheter and Surgical Aortic Valve Replacement: A Transatlantic Study

Myocardial ischemia/reperfusion-related oxidative stress as a result of cardiopulmonary bypass is thought to contribute to the adverse clinical outcomes following surgical aortic valve replacement (SAVR). Although the acute response following this procedure has been well characterized, much less is known about the nature and extent of oxidative stress induced by the transcatheter aortic valve replacement (TAVR) procedure. We therefore sought to examine and directly compare the oxidative stress response in patients undergoing TAVR and SAVR. A total of 60 patients were prospectively enrolled in this exploratory study, 38 patients undergoing TAVR and 22 patients SAVR. Reduced and oxidized glutathione (GSH, GSSG) in red blood cells as well as the ferric-reducing ability of plasma (FRAP) and plasma concentrations of 8-isoprostanes were measured at baseline (S1), during early reperfusion (S2), and 6-8 hours (S3) following aortic valve replacement (AVR). TAVR and SAVR were successful in all patients. Patients undergoing TAVR were older (79.3 ± 9.5 vs. 74.2 ± 4.1 years; P < 0.01) and had a higher mean STS risk score (6.6 ± 4.8 vs. 3.2 ± 3.0; P < 0.001) than patients undergoing SAVR. At baseline, FRAP and 8-isoprostane plasma concentrations were similar between the two groups, but erythrocytic GSH concentrations were significantly lower in the TAVR group. After AVR, FRAP was markedly higher in the TAVR group, whereas 8-isoprostane concentrations were significantly elevated in the SAVR group. In conclusion, TAVR appears not to cause acute oxidative stress and may even improve the antioxidant capacity in the extracellular compartment.

Dietary Saturated Fat Promotes Arrhythmia by Activating NOX2 (NADPH Oxidase 2)

BACKGROUND

Obesity and diets high in saturated fat increase the risk of arrhythmias and sudden cardiac death. However, the molecular mechanisms are not well understood. We hypothesized that an increase in dietary saturated fat could lead to abnormalities of calcium homeostasis and heart rhythm by a NOX2 (NADPH oxidase 2)-dependent mechanism.

METHODS

We investigated this hypothesis by feeding mice high-fat diets. In vivo heart rhythm telemetry, optical mapping, and isolated cardiac myocyte imaging were used to quantify arrhythmias, repolarization, calcium transients, and intracellular calcium sparks.

RESULTS

We found that saturated fat activates NOX (NADPH oxidase), whereas polyunsaturated fat does not. The high saturated fat diet increased repolarization heterogeneity and ventricular tachycardia inducibility in perfused hearts. Pharmacological inhibition or genetic deletion of NOX2 prevented arrhythmogenic abnormalities in vivo during high statured fat diet and resulted in less inducible ventricular tachycardia. High saturated fat diet activates CaMK (Ca2+/calmodulin-dependent protein kinase) in the heart, which contributes to abnormal calcium handling, promoting arrhythmia.

CONCLUSIONS

We conclude that NOX2 deletion or pharmacological inhibition prevents the arrhythmogenic effects of a high saturated fat diet, in part mediated by activation of CaMK. This work reveals a molecular mechanism linking cardiac metabolism to arrhythmia and suggests that NOX2 inhibitors could be a novel therapy for heart rhythm abnormalities caused by cardiac lipid overload.

No association between coffee consumption and risk of atrial fibrillation: A Mendelian randomization study

BACKGROUND AND AIMS

Some observational studies have found that habitual coffee and caffeine consumption might reduce the risk of atrial fibrillation (AF). We conducted a two-sample Mendelian randomization study to explore the potential association between coffee consumption and AF.

METHODS AND RESULTS

This study was based on summary-level data from the Atrial Fibrillation Consortium, including 588 190 individuals (65 446 cases and 522 744 non-cases). Nine single-nucleotide polymorphisms associated with coffee consumption at significance level of P < 5 × 10^-8 were used as instrumental variables and were obtained from a genome-wide association study that included up to 375 833 individuals. The odds ratio of AF per genetically-predicted 50% increase of coffee consumption was 0.98 (95% confidence interval, 0.88, 1.10; P = 0.80) in the standard inverse-variance weighted analysis. Results were consistent in sensitivity analyses using the weighted median and MR-Egger methods, and no directional pleiotropy (P = 0.37) was observed. Moreover, complementary analyses that separated the coffee-related single-nucleotide polymorphisms based on their association with blood levels of caffeine metabolites (lower, higher, unrelated or unknown association) revealed no association with AF.

CONCLUSIONS

This study does not support a causal association between habitual coffee consumption and risk of AF.

Olive oil intake and risk of atrial fibrillation in the SUN cohort

BACKGROUND AND AIMS

A Mediterranean-type diet enriched with extra virgin olive oil has been associated with a reduction in the incidence of atrial fibrillation (AF) in a population at high cardiovascular risk. However, no study has replicated these findings. In our study, we analyzed the association between olive oil consumption and AF in the SUN project, a cohort with young Spanish adults at low cardiovascular risk.

METHODS AND RESULTS

We included all participants without prevalent AF at baseline (18,118 participants). Incident AF cases were confirmed by a cardiologist following a prespecified protocol. We used multivariable repeated-measurement Cox models adjusted for possible confounders (sex, age, BMI, and several classic cardiovascular risk factors). After a mean follow-up of 10.1 years, 94 AF incident cases were confirmed. Comparing to the lowest category of consumption (<7.9 g/d), the multivariable models showed hazard ratios (IC 95%) of 1.52 (0.93-2.48) for low-to-moderate, 1.44 (0.83-2.47) for moderate-to-high and 1.27 (0.56-2.86) for high olive oil intake. In a subgroup analysis stratified by overweight, an inverse although non-significant association was found only among overweight participants when we compared the highest vs the lowest category of consumption (p for interaction = 0.043).

CONCLUSION

No association between olive oil and AF was found in this low-risk cohort, although the effect of extra-virgin olive oil on AF prevention especially among people with overweight deserves further investigation.

New-Onset Atrial Fibrillation in Adult Patients After Cardiac Surgery

Purpose of Review

An overview of recent literature regarding pathophysiology, risk factors, prophylaxis, and treatment of new-onset atrial fibrillation (AF) in post-cardiac surgical patients.

Recent Findings

AF is the most frequent adverse event after cardiac surgery with significant associated morbidity, mortality, and financial cost. Its causes are multifactorial, and models to stratify patients into risk categories are progressing but a consistent, evidence-based system has not yet been developed. Pharmacologic and surgical interventions to prevent and treat this complication have been an area of ongoing research and recent societal guidelines reflect this.

Summary

Inconsistencies remain surrounding how to best identify higher-risk AF patients, which interventions should be used to prevent and treat AF, and which patient groups should receive these interventions. The evidence for these available strategies and their place in contemporary guidelines are summarized.

Plasma Malondialdehyde and Risk of New-Onset Diabetes after Transplantation in Renal Transplant Recipients: A Prospective Cohort Study

New-onset diabetes after transplantation (NODAT) is a frequent complication in renal transplant recipients (RTR). Although oxidative stress has been associated with diabetes mellitus, data regarding NODAT are limited. We aimed to prospectively investigate the long-term association between the oxidative stress biomarker malondialdehyde (measured by high-performance liquid chromatography) and NODAT in an extensively phenotyped cohort of non-diabetic RTR with a functioning graft ≥1 year. We included 516 RTR (51 ± 13 years-old, 57% male). Median plasma malondialdehyde (MDA) was 2.55 (IQR, 1.92-3.66) µmol/L. During a median follow-up of 5.3 (IQR, 4.6-6.0) years, 56 (11%) RTR developed NODAT. In Cox proportional-hazards regression analyses, MDA was inversely associated with NODAT, independent of immunosuppressive therapy, transplant-specific covariates, lifestyle, inflammation, and metabolism parameters (HR, 0.55; 95% CI, 0.36-0.83 per 1-SD increase; p < 0.01). Dietary antioxidants intake (e.g., vitamin E, α-lipoic acid, and linoleic acid) were effect-modifiers of the association between MDA and NODAT, with particularly strong inverse associations within the subgroup of RTR with relatively higher dietary antioxidants intake. In conclusion, plasma MDA concentration is inversely and independently associated with long-term risk of NODAT in RTR. Our findings support a potential underrecognized role of oxidative stress in post-transplantation glucose homeostasis.

Redox State in Atrial Fibrillation Pathogenesis and Relevant Therapeutic Approaches

BACKGROUND

Myocardial redox state is a critical determinant of atrial biology, regulating cardiomyocyte apoptosis, ion channel function, and cardiac hypertrophy/fibrosis and function. Nevertheless, it remains unclear whether the targeting of atrial redox state is a rational therapeutic strategy for atrial fibrillation prevention.

OBJECTIVE

To review the role of atrial redox state and anti-oxidant therapies in atrial fibrillation.

METHOD

Published literature in Medline was searched for experimental and clinical evidence linking myocardial redox state with atrial fibrillation pathogenesis as well as studies looking into the role of redoxtargeting therapies in the prevention of atrial fibrillation.

RESULTS

Data from animal models have shown that altered myocardial nitroso-redox balance and NADPH oxidases activity are causally involved in the pathogenesis of atrial fibrillation. Similarly experimental animal data supports that increased reactive oxygen / nitrogen species formation in the atrial tissue is associated with altered electrophysiological properties of atrial myocytes and electrical remodeling, favoring atrial fibrillation development. In humans, randomized clinical studies using redox-related therapeutic approaches (e.g. statins or antioxidant agents) have not documented any benefits in the prevention of atrial fibrillation development (mainly post-operative atrial fibrillation risk).

CONCLUSION

Despite strong experimental and translational data supporting the role of atrial redox state in atrial fibrillation pathogenesis, such mechanistic evidence has not been translated to clinical benefits in atrial fibrillation risk in randomized clinical studies using redox-related therapies.