Implantable cardioverter defibrillator (ICD) therapy is effective in
primary and secondary prevention of sudden cardiac death among patients with
prior myocardial infarction and depressed ejection fraction. However, conclusive
evidence of survival benefit in patients with nonischemic cardiomyopathy (NICM)
is still lacking.
To determine whether ICD therapy reduces all-cause mortality in patients
MEDLINE (1966-2004), EMBASE (1991-2004), the Cochrane Central Register
of Controlled Trials (through first quarter, 2004), reports presented at scientific
meetings (2003-2004), and bibliographic review of secondary sources. Search
terms included defibrillator, randomized controlled trials,
clinical trials, andsudden death.
Eligible studies were prospective randomized controlled trials of ICD
or combined cardiac resynchronization therapy and defibrillator (CRT-D) vs
medical therapy enrolling at least some individuals with NICM and reporting
all-cause mortality as an outcome. Of 675 potentially relevant articles screened
initially, 8 reports of randomized trials enrolling a total of 2146 patients
with NICM were included.
Included studies were reviewed to determine the number of patients randomized,
mean duration of follow-up, primary end point, mortality of ICD cohort, and
mortality of control cohort.
Five primary prevention trials enrolling 1854 patients with NICM were
identified; pooled analysis suggested a significant reduction in total mortality
among patients randomized to ICD or CRT-D vs medical therapy (risk ratio [RR], 0.69;
95% confidence interval [CI], 0.55-0.87; P = .002).
Mortality reduction remained significant even after elimination of CRT-D trials.
Two of the 3 secondary prevention trials presented subgroup estimates for
ICD efficacy in NICM. Pooled analysis of these secondary prevention trials
(n = 256 patients with NICM) indicated an equivalent but nonsignificant
mortality reduction with ICD therapy (RR, 0.69; 95% CI, 0.39-1.24; P = .22). Analysis of all 7 trials combined demonstrated
a statistically significant 31% overall reduction in mortality with ICD therapy
(RR, 0.69; 95% CI, 0.56-0.86; P = .002).
ICD therapy appears to significantly reduce mortality in selected patients