The risk for sudden cardiac death (SCD) is particularly high in the early months after a myocardial infarction (MI). However, two trials of prophylactic implantable cardioverter-defibrillator (ICD) placement after MI failed to show a survival benefit in ICD recipients (JW Cardiol Jan 28 2005 and Oct 7 2009), in contrast to results of other ICD trials. To examine this lack of benefit more closely, investigators studied data from VALIANT, an international trial of valsartan in MI survivors.

Of 14,703 participants with left ventricular dysfunction, clinical heart failure, or both, 2878 died during a median of 25 months of follow-up, and autopsy results were available for 398. Of these, the cause of death was clinically judged to be SCD in 105; autopsy revealed recurrent MI or cardiac rupture in 44; pump failure in 4; and stroke, pulmonary embolism, and drug overdose in 1 each. The proportion of clinically adjudicated SCDs that were nonarrhythmic on autopsy was even more dramatic during the first post-MI month (24 of 30 deaths).

Comment: This unique analysis of the causes of SCD early after MI yielded a surprising result: Nearly 50% of SCDs in the first 2 years — and 80% of SCDs within the first month — were nonarrhythmic. If confirmed in other populations, this finding would explain the failure of ICDs to prevent SCD in previous trials. This study appears to validate current guidelines that call for a 40-day delay in ICD placement after an acute MI.

Published in Journal Watch Cardiology August 11, 2010