Sudden Cardiac Death in Dilated Cardiomyopathies

Implantable cardioverter defibrillator for primary prevention in patients with non-ischemic cardiomyopathy in the era of novel therapeutic agents- meta-analysis

Background

Evidence regarding the mortality benefit of implantable cardioverter defibrillator (ICD) non-ischemic dilated cardiomyopathy (NIDCM) is inconsistent. The most recent randomized study, the DANISH trial, did not find improved outcomes with ICD. However, based on previous studies and meta-analyses, current guidelines still highly recommend ICD implantation in NIDCM patients. The introduction of novel medications for heart failure improved the clinical outcome dramatically. We aimed in this study to evaluate the effect of Angiotensin Receptor-Neprilysin Inhibitors (ARNi) and sodium-glucose transport protein 2 inhibitors (SGLT2i) on the mortality benefit of ICD in NIDCM.

Methods

We used a previous metanalysis algorithm and added an updated comprehensive literature search in PubMed for randomized control trials that examined the mortality benefit of ICD in NIDCM vs. optimal medical treatment. The primary outcome included death from any cause. We did a meta-regression analysis to search for a single independent factor affecting mortality. Using previous data, we evaluated the theoretical effect of ICD implementation on patients treated with SGLT2 inhibitors and ARNi.

Results

No new articles were added to the results of the previous meta-analysis. 2,622 patients with NIDCM from 5 cohort studies published between 2002 and 2016 were included in the analysis. 50% of them underwent ICD implantation for primary prevention of sudden cardiac death, and 50% did not. ICD was associated with a significantly decreased risk for death from any cause compared to control (OR = 0.79, 95%CI: 0.66-0.95, p = 0.01, I² = 0%). The theoretical addition of ARNi and the SGLT2 inhibitor dapagliflozin did not change the significant mortality effect of ICD (OR = 0.82, 95%CI: 0.7-0.9, p = 0.001, I² = 0%) and (OR = 0.82, 95%CI: 0.7-0.9, p = 0.001, I² = 0%). A meta-regression revealed no association between death from any cause and left bundle branch block (LBBB), use of amiodarone, use of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers, year initiated enrollment, and the year ended enrollment (R² = 0.0).

Conclusion

In patients with NIDCM, the addition of ARNi and SGLT2i did not affect the mortality advantages of ICD for primary prevention.

PROSPERO registry number

https://www.crd.york.ac.uk/prospero/, identifier: CRD42023403210.

Autoimmune channelopathies as a novel mechanism in cardiac arrhythmias

Cardiac arrhythmias confer a considerable burden of morbidity and mortality in industrialized countries. Although coronary artery disease and heart failure are the prevalent causes of cardiac arrest, in 5-15% of patients, structural abnormalities at autopsy are absent. In a proportion of these patients, mutations in genes encoding cardiac ion channels are documented (inherited channelopathies), but, to date, the molecular autopsy is negative in nearly 70% of patients. Emerging evidence indicates that autoimmunity is involved in the pathogenesis of cardiac arrhythmias. In particular, several arrhythmogenic autoantibodies targeting specific calcium, potassium, or sodium channels in the heart have been identified. Experimental and clinical studies demonstrate that these autoantibodies can promote conduction disturbances and life-threatening tachyarrhythmias by inducing substantial electrophysiological changes. In this Review, we propose the term 'autoimmune cardiac channelopathies' to define this novel pathogenic mechanism of cardiac arrhythmias, which could be more frequent and clinically relevant than previously appreciated. Indeed, pathogenic autoantibodies against ion channels are detectable not only in patients with manifest autoimmune disease, but also in apparently healthy individuals, which suggests a causal role in some cases of unexplained arrhythmias and cardiac arrest. Considering this possibility and performing specific testing in patients with 'idiopathic' rhythm disturbances could create novel treatment opportunities.

Evaluating the Efficacy and Safety of Internal Cardioversion with Implantable Cardioverter Defibrillator Device for Atrial Fibrillation in Systolic Heart Failure Patients

BACKGROUND

Atrial fibrillation (AF) commonly observed in patients with heart failure and cardioversion was often needed to restore the sinus rhythm. Previously, there is no study evaluating usefulness of internal cardioversion with implantable cardioverter defibrillator (ICD) device. In this study, we aimed to compare the efficacy and long-term effects of internal cardioversion with ICD devices compared to conventional external cardioversion in patients with AF and heart failure.

METHODS

Seventy patients with AF and heart failure who underwent electrical cardioversion were enrolled in the study. Forty patients (mean age 65.36 ± 10.37, 35 male) were assigned to undergo internal cardioversion with approximately 35 J shocks delivered through the ICD electrode. Standard external cardioversion was performed for the remaining patients (30 patients; mean age 66.20 ± 11.89; 24 male) that were similar with regard to baseline, and electrocardiographic characteristics.

RESULTS

Sinus rhythm was restored in 32 of 40 patients (80.0%) assigned to internal cardioversion compared with 25 of 30 patients (83.3%) assigned to external cardioversion (P = 0.725). We did not witness any serious complication during the procedure and hospitalization. On the follow-up, there was no statistically significant difference in recurrence of AF and incidence of major cardiovascular events between the internal and external cardioversion groups.

CONCLUSIONS

Internal cardioversion with ICD device is an effective and safe method to restore sinus rhythm in heart failure patients with AF.

Sudden cardiac death in the young: the bogeyman

Sudden cardiac death in the young is a relatively uncommon but marked event usually related to congenital diseases or anomalies. Despite the prevalence of each condition being variable, most common causes include primary myocardial diseases and arrhythmic disorder, frequently with inheritance pattern. Sudden cardiac death is usually preceded by symptoms, thus making personal and family history fundamental for its prevention. Nevertheless, in more than 50% of cases, sudden cardiac death is the first manifestation of the disease. In this review, we describe the different causes of sudden cardiac death, their incidence, and currently used preventive strategies.