Risk and Protective Factors for Sudden Cardiac Death: An Umbrella Review of Meta-Analyses

Recent Advances in Cardiac Resynchronization Therapy: Current Treatment and Future Direction

Cardiac Resynchronization Therapy (CRT) has been established as a major component of heart failure management, resulting in a significant reduction in patient morbidity and death for patients with increased QRS duration, low left ventricular ejection fraction (LVEF), and high risk of arrhythmias. The ability to synchronize both ventricles, lower heart failure hospitalizations, and optimize clinical outcomes are some of the attractive characteristics of biventricular pacing, or CRT. However, the high rate of CRT non-responders has led to the development of new modalities including leadless CRT pacemakers (CRT-P) and devices focused on conduction system pacing (CSP). This comprehensive review aims to present recent findings from CRT clinical trials and systematic reviews that have been published that will likely guide future directions in patient care.

The Interplay of Type 2 Diabetes Status, Cardiorespiratory Fitness Level, and Sudden Cardiac Death: A Prospective Cohort Study

Background

To evaluate the individual and joint effects of type 2 diabetes (T2D) status and cardiorespiratory fitness (CRF) level with sudden cardiac death (SCD) risk.

Methods

Prevalent T2D was defined based on guideline recommendations, and CRF level was assessed using a respiratory gas-exchange analyzer during exercise testing at baseline, in 2308 men aged 42-61 years. T2D status was classified as either "Yes" or "No," and CRF level was classified as low, medium, or high. Cox regression analysis was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for SCD.

Results

A total of 264 SCDs occurred during a median follow-up of 28.1 years. Comparing Yes vs No history of T2D, the multivariable-adjusted HR (95% CI) for SCD was 1.79 (1.19-2.72). Comparing low vs high CRF levels, the corresponding adjusted HR (95% CI) for SCD was 1.77 (1.21-2.58). The HRs persisted when T2D status was further adjusted for CRF level, and vice versa. Compared with No-T2D & medium-high CRF level, men with No-T2D & low CRF and those with Yes-T2D & low CRF had an increased SCD risk: (HR = 1.87, 95% CI, 1.38-2.55) and (HR = 3.34, 95% CI, 2.00-5.57), respectively. No significant association occurred between men with Yes-T2D & medium-high CRF and SCD risk (HR = 1.46, 95% CI, 0.46-4.65). Modest evidence indicated the presence of additive and multiplicative interactions between T2D status and CRF level, in relation to SCD.

Conclusions

An interplay exists between T2D status, CRF level, and SCD risk in middle-aged and older men. Higher CRF levels may mitigate the increased SCD risk observed in men with T2D.

Ertugliflozin to Reduce Arrhythmic Burden in Patients with ICDs/CRT-Ds

BACKGROUND

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have beneficial pleiotropic effects, contributing to improved cardiovascular and renal outcomes for patients with and without diabetes. The impact of SGLT2is on arrhythmic burden remains largely unexplored through randomized trials.

METHODS

In this multicenter, double-blind, randomized, placebo-controlled trial, we investigated the effects of ertugliflozin on arrhythmic burden among patients with heart failure with an ejection fraction less than 50%. All patients had an implantable cardioverter-defibrillator (ICD) with or without a cardiac resynchronization therapy device (CRT-D) and were randomized (1:1) to receive either ertugliflozin 5 mg once daily or placebo. The primary end point was the number of incident sustained (>30 seconds) ventricular tachycardia or ventricular fibrillation events from baseline to week 52. Secondary end points included the total number of non-sustained ventricular tachycardias, appropriate ICD therapies, changes in N-terminal pro-brain-type natriuretic peptide (NTproBNP) levels, and the number of heart failure hospitalizations.

RESULTS

Randomization was prematurely terminated, after class IA guideline recommendations were published for SGLT2is in patients with heart failure regardless of the ejection fraction. The final analysis included 46 patients (11% of the originally planned sample size). The yearly rate of the primary end point was 3.5 (95% confidence interval [CI] 2.8 to 4.4) with ertugliflozin compared with 13.3 with placebo (95% CI 11.8 to 14.8; rate ratio 0.16, 95% CI 0.04 to 0.61; P<0.001). There were no apparent differences in appropriate ICD therapies, hospitalizations, NTproBNP levels, or predefined adverse and serious adverse events.

CONCLUSIONS

Ertugliflozin reduced sustained ventricular tachycardia or ventricular fibrillation events in adults with heart failure and an ICD compared with placebo; however, our trial ended early and thus results should be interpreted with caution. (Funded by Investigator-initiated Studies Program of Merck Sharp & Dohme Corp and Pfizer; EudraCT number, 2020-002581-14; ClinicalTrials.gov number NCT04600921.).

Fentanyl and Sudden Death-A Postmortem Perspective for Diagnosing and Predicting Risk

Sudden, unexpected deaths are extremely difficult for families, especially when the victim is a child. Most sudden deaths occur due to cardiovascular issues, and a smaller number (approximately one-quarter) are attributed to other causes, such as epilepsy. The medicinal and non-medicinal use of the synthetic opioid fentanyl, which can cause breathing problems, is frequently involved in these deaths. It is also being found more often in autopsies of sudden death cases, and the number of overdose deaths from illicit drugs containing fentanyl is increasing. There are cases in which it is mixed with other drugs. A gene known as the KCNH2 gene or human ether-a-go-go-related gene (hERG), involved in the heart's electrical activity, can be related to abnormal heart rhythms. This gene, along with others, may play a role in sudden deaths related to fentanyl use. In response, we have examined the scientific literature on genetic variations in the KCNH2 gene that can cause sudden death, the impact of fentanyl on this process, and the potential benefits of genetic testing for the victims to offer genetic counseling for their family members.

Arrhythmias and Sudden Cardiac Death

Ventricular tachyarrhythmias remain a major cause of sudden cardiac arrest (SCA) that leads to sudden cardiac death (SCD). Primary prevention strategies to prevent SCD include promoting a healthy lifestyle, following United States Preventive Service Task Force recommendations related to cardiovascular disease, and controlling comorbid conditions. For a patient experiencing SCA, early cardiopulmonary resuscitation and defibrillation should be performed. Implantable cardioverter defibrillators are more effective at secondary prevention compared with drug therapy but medications such as amiodarone, beta-blockers, and sotalol may be helpful adjuncts to reduce the risk of SCD or improve a patient's symptoms (eg, palpitations and inappropriate defibrillator shocks).

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

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

Sudden Cardiac Death: An Update on Commotio Cordis

Sudden cardiac death (SCD) is one of the leading causes of cardiovascular mortality, and it is caused by a diverse array of conditions. Among these is commotio cordis, a relatively infrequent but still significant cause, often seen in young athletes involved in competitive or recreational sports. It is known to be caused by blunt trauma to the chest wall resulting in life-threatening arrhythmia (typically ventricular fibrillation). The current understanding pertains to blunt trauma to the precordium, with an outcome depending on factors such as the type of stimulus, the force of impact, the qualities of the projectile (shape, size, and density), the site of impact, and the timing of impact in relation to the cardiac cycle. In the management of commotio cordis, a history of preceding blunt chest trauma is usually encountered. Imaging is mostly unremarkable except for ECG, which may show malignant ventricular arrhythmias. Treatment is focused on emergent resuscitation with the advanced cardiac life support protocol algorithm, with extensive workup following the return of spontaneous circulation. In the absence of underlying cardiovascular pathologies, implantable cardiac defibrillator insertion is not beneficial, and patients can even resume physical activity if the workup is unremarkable. Proper follow-up is also key in the management and monitoring of re-entrant ventricular arrhythmias, which are amenable to ablative therapy. Prevention of this condition involves protecting the chest wall against blunt trauma, especially with the use of safety balls and chest protectors in certain high-risk sporting activities.  This study aims to elucidate the current epidemiology and clinical management of SCD with a particular focus on a rarely explored etiology, commotio cordis.

Sudden Cardiac Death in Young Individuals: A Current Review of Evaluation, Screening and Prevention

Sudden cardiac death (SCD) can affect all age groups, including young persons. While less common in the age < 35 population, the occurrence of SCD in the young raises concern, with multiple possible etiologies and often unanswered questions. While coronary artery disease is the leading cause in those > 35 years of age, the younger population faces a different subset of pathologies associated with SCD, including arrhythmias and cardiomyopathies. The tragic nature of SCD in the young entails that we explore and implement available screening methods for this population, and perform the necessary investigations such as electrocardiography (ECG) and echocardiography. In this review, we not only explore the vast etiology associated with SCD in those age < 35, but emphasize evaluation methods, who is at risk, and delve into screening of SCD in potential victims and their family members, in an attempt to prevent this traumatic event. Future research must work towards establishing preventative measures in order to reduce SCD, particularly unexplained SCD in the young.