medwireNews: Implantable cardioverter-defibrillators (ICDs) are no more likely than amiodarone hydrochloride to prevent death from any cause in patients with Chagas cardiomyopathy, suggest findings from the CHAGASICS trial.
Martino Martinelli-Filho (Hospital das Clínicas da Universidade de São Paulo, Brazil) and colleagues did find, however, that patients using ICDs were less likely than those given amiodarone to experience sudden cardiac death (SCD) or heart failure (HF).
The study involved 323 patients with Chagas disease from 13 medical centers in Brazil who had at least one episode of nonsustained ventricular tachycardia (NSVT) and a moderate-to-high mortality risk, with a Rassi score of at least 10 points. Most (63.7%) of the patients were at high risk, with a score between 12 and 20 points.
Factors included in the RASSI score are New York Heart Association (NYHA) functional classes III to IV, cardiomegaly, global or segmental ventricular dyssynergy, NSVT, low voltage on electrocardiography, and male sex. NSVT was defined as at least three successive ventricular ectopic beats (up to 30 seconds long), with a heart rate greater than 120 beats/minute.
The participants (mean age 57.4 years, 57.3% men) were randomly assigned to either have an ICD implanted or to receive daily amiodarone, at an oral loading dose of 600 mg for 10 days followed by a maintenance dose of 200–400 mg/day for the duration of the study.
“Although treatment crossover in either direction was strongly discouraged, it was permitted when it was clearly in the patient’s best interest,” the investigators note in JAMA Cardiology.
They also point out that due to administrative reasons, the trial was stopped prematurely, meaning that the study population size was smaller than the intended 1100 patients.
At a median follow-up of 3.6 years, 38.2% of patients in the ICD group had died from any cause, as had 38.6% of those in the amiodarone group. Cardiovascular causes were the most common contributing factor (29.3 vs 30.1%, respectively) followed by HF (19.7 vs 11.4%), with the differences nonsignificant in each case.
Martinelli-Filho and team point out that there might be a time-dependent benefit of ICD over medical therapy, finding that all-cause mortality was 32% lower in the ICD group than the amiodarone group at 3 years, 17% lower at 4 years, and just 7% lower at 5 years of follow-up.
“This can possibly be explained by the fact that VT and [ventricular fibrillation] occurred mainly in the first 4 years of follow-up, when the ICD was effective in reducing mortality,” the team remarks. “After 4 years, the mode of death in the ICD group became predominantly HF worsening.”
ICD use was associated with significant reductions in the risk for sudden cardiac death and HF hospitalization, the investigators report. The former occurred in 3.8% of those in the ICD group versus 13.9% of those in the amiodarone group, giving a significant risk reduction with ICD use of 75%. HF hospitalization was reduced a significant 54% with ICD use, occurring in a respective 8.9% versus 16.9% of patients, and there was a 90% reduction in the risk for bradycardia requiring a pacemaker or pacing with a previously implanted device, with rates of 1.9% versus 16.3%.
The researchers note that these differences “could not be ascribed to differences in the use of concomitant medications,” as the “use of concomitant medical therapy, mostly aiming at control of HF, was well balanced between the study groups.”
Adverse events occurred in a similar proportion of patients, affecting 4.3% of those in the ICD group and 3.1% of those in the amiodarone group, the most common of which were related to lead dysfunction for the former group and iatrogenic hypothyroidism for the latter.
Given that the trial recruited fewer participants than intended, Martinelli-Filho et al say the findings “should be interpreted cautiously,” adding that “[f]urther studies are warranted to confirm the evidence generated by this trial.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2024 Springer Healthcare Ltd, part of the Springer Nature Group