LAUSR

TO THE EDITOR: On the basis of data pooled from SCD-HeFT, AMIOVIRT (Amiodarone Versus Implantable Cardioverter-Defibrillator Randomized Trial), CAT (Cardiomyopathy Trial), DEFINITE (Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation), and DANISH, Koodziejczak and colleagues conclude that prophylactic ICDs compared with conventional therapy reduce all-cause mortality in patients with nonischemic cardiomyopathy (1). However, they considered recipients of conventional therapy from SCD-HeFT to be both the placebo and amiodarone groups. This factor affects the generalizability of their results. Amiodarone is not a guideline-based therapy for nonischemic cardiomyopathy. It might be harmful if used for primary prevention, particularly in patients with advanced heart failure; in patients in SCD-HeFT with New York Heart Association class III congestive heart failure, amiodarone showed a 44% greater risk for death than placebo. Other meta-analyses in this field thus used only the placebo group from SCD-HeFT. Generalizability may also have been compromised by including AMIOVIRT, where only patients with nonsustained ventricular tachycardia were enrolled and amiodarone was compared with ICDs. Furthermore, in SCD-HeFT, mortality among patients with nonischemic cardiomyopathy was calculated using a subgroup; this method is observational in nature and hypothesis-generating. Thus, a sensitivity analysis excluding SCD-HeFT should have been reported. By removing this trial, the pooled risk ratio becomes nonsignificant (risk ratio, 0.87 [95% CI, 0.72 to 1.05]; P= 0.138), and removing any 4 trials maintains their summary results. This finding suggests that the results favoring ICDs for patients with nonischemic cardiomyopathy were driven by SCD-HeFT only. The other trials exclusively enrolled patients with nonischemic cardiomyopathy, and all showed that ICDs did not significantly improve survival: The pooled risk ratio was not associated with improved survival (P= 0.138). Koodziejczak and colleagues state that their findings are consistent with current guidelines recommending prophylactic ICDs for patients with nonischemic cardiomyopathy. Those guidelines were published before DANISH (2, 3), a study that should be considered the best in this field because the use of such lifesaving therapies as -blockers, aldosterone antagonists, angiotensin-converting enzyme inhibitors, and cardiac resynchronization was higher than in all prior studies. Indeed, no randomized trial exclusively enrolling patients with nonischemic cardiomyopathy has ever shown survival benefits with prophylactic ICDs. In addition, clinical practice guidelines are largely developed from lower levels of evidence or expert opinion, and a substantial number of recommendations has been downgraded or reversed over time with emerging strong evidence (4, 5). In summary, current evidence is not definitive that prophylactic ICDs improve survival for all patients with nonischemic cardiomyopathy. Additional studies in this field are needed because ICDs are both expensive and associated with serious complications.