Dataset for amiodarone adverse events compared to placebo using data from randomized controlled trials

Assessment of Comorbidity Burden and Treatment Response: Reanalysis of the SCD-HEFT Trial

INTRODUCTION

Comorbidity burden may be associated with treatment-effect heterogeneity (HTE) in clinical trials, which could alter the interpretation or clinical translation of results for many patients in the real world.

OBJECTIVE

In this analysis, we sought to determine the distribution of multimorbidity scores in patients enrolled in SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) and tested the association between comorbidity burden and treatment efficacy for the outcome of all-cause death.

METHODS

Each patient was assigned a modified Charlson Comorbidity Index (mCCI) score from 1 to 14 based on available enrollment data. We investigated the relationship between mCCI score and time to all-cause death using Cox proportional hazards models. Models were fit for quartiles of the comorbidity index, reference coding was used, with quartile 1 (Q1; mCCI score of 1-2) selected as the reference. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were reported from these models. Following the same analysis framework as the original manuscript, patients assigned to amiodarone or implantable cardioverter-defibrillator (ICD) were compared with those assigned to placebo in separate Cox models. Each model included the mCCI score in quartiles, group assignment, and an interaction term for the quartile and group assignment. HRs and corresponding 97.5% CIs were reported from these models.

RESULTS

The majority of patients had an mCCI score ≤5 (75.4%), and mortality risk was associated with increasing score. The HRs for Q2 (score 3), Q3 (scores 4-5), and Q4 (scores ≥6) were 1.46 (97.5% CI 1.06-1.99), 3.03 (97.5% CI 2.35-3.90), and 4.51 (97.5% CI 3.46-5.88), respectively. For the subgroup analysis, amiodarone was not associated with a significant difference compared with placebo for individuals in Q1-Q3; however, it was associated with an increase in death for those in Q4 (HR 1.50; 97.5% CI 1.03-2.18). ICD was associated with a significant reduction in death compared with placebo for individuals in Q1 and Q3 (HR 0.42; 97.5% CI 0.20-0.84 and HR 0.70; 97.5% CI 0.50-0.97, respectively) but not for those in Q2 or Q4. Interaction testing across subgroups suggested HTE for amiodarone (p = 0.07) and ICD (p = 0.08) versus placebo across mCCI quartiles.

CONCLUSIONS

Increasing comorbidity burden was associated with HTE when evaluating amiodarone and ICD compared with placebo in the SCD-HeFT trial. Our results highlight the importance of enrolling diverse patient populations in clinical trials and considering the possibility of HTE when translating results to clinical practice.

Advanced Therapies for Ventricular Arrhythmias in Patients With Chagasic Cardiomyopathy: JACC State-of-the-Art Review

Chagas disease is caused by infection from the protozoan parasite Trypanosoma cruzi. Although it is endemic to Latin America, global migration has led to an increased incidence of Chagas in Europe, Asia, Australia, and North America. Following acute infection, up to 30% of patients will develop chronic Chagas disease, with most patients developing Chagasic cardiomyopathy. Chronic Chagas cardiomyopathy is highly arrhythmogenic, with estimated annual rates of appropriate implantable cardioverter-defibrillator therapies and electrical storm of 25% and 9.1%, respectively. Managing arrhythmias in patients with Chagasic cardiomyopathy is a major challenge for the clinical electrophysiologist, requiring intimate knowledge of cardiac anatomy, advanced training, and expertise. Endocardial-epicardial mapping and ablation strategy is needed to treat arrhythmias in this patient population, owing to the suboptimal long-term success rate of endocardial mapping and ablation alone. We also describe innovative approaches to improve acute and long-term clinical outcomes in patients with refractory ventricular arrhythmias following catheter ablation, such as bilateral cervicothoracic sympathectomy and bilateral renal denervation, among others.

Inhibitory Effects of Dronedarone on Small Conductance Calcium Activated Potassium Channels in Patients with Chronic Atrial Fibrillation: Comparison to Amiodarone

BACKGROUND Dysfunction of small conductance calcium activated potassium (SK) channels plays a vital role in atrial arrhythmogenesis. Amiodarone and dronedarone are the most effective class III antiarrhythmic drugs. It is unclear whether the antiarrhythmic effect of amiodarone and dronedarone is related to SK channel inhibition. MATERIAL AND METHODS Tissue samples were obtained from the right atria of 46 patients with normal sinus rhythm and 39 patients with chronic atrial fibrillation. Isolated atrial myocytes were obtained by enzymatic dissociation. KCNN2 (SK2) channels were transiently expressed in human embryonic kidney (HEK)-293 cells. SK currents were recorded using whole-cell conventional patch clamp techniques. RESULTS Amiodarone and dronedarone showed a concentration-dependent inhibitory effect on SK currents (IKAS) in atrial myocytes from normal sinus rhythm patients and chronic atrial fibrillation patients. The suppressed efficacy of dronedarone and amiodarone on IKAS was greater in atrial myocytes from chronic atrial fibrillation patients than that from normal sinus rhythm patients. Furthermore, in patients with chronic atrial fibrillation, the IC₅₀ value was 2.42 µM with dronedarone and 8.03 µM with amiodarone. In HEK-293 cells with transiently transfected SK2 channels, both dronedarone and amiodarone had a dose-dependent inhibitory effect on IKAS. The IC₅₀ value was 1.7 µM with dronedarone and 7.2 µM with amiodarone in cells from patients with chronic atrial fibrillation. Compared to amiodarone, dronedarone is more efficacy to inhibit IKAS and could be a potential intervention for patients with chronic atrial fibrillation. CONCLUSIONS Dronedarone provides a great degree of IKAS inhibition in atrial myocytes from chronic atrial fibrillation than amiodarone. IKAS might be a potential target of amiodarone and dronedarone for the management of chronic atrial fibrillation.