Device Therapy for Sudden Cardiac Death Prophylaxis After Acute Coronary Syndrome: When and Why?

Implantable cardioverter-defibrillators (ICDs) are a powerful tool in preventing sudden cardiac death due to ventricular arrhythmias in ischemic cardiomyopathy. ICD indications and timing in acute coronary syndromes are unclear. PURPOSE OF REVIEW: We reviewed several trials that delineated the indications for a cardiac defibrillator in patients with coronary artery disease. RECENT FINDINGS: The role of cardiac defibrillators in secondary prevention has been well established by AVID, CIDS, and CASH trials. AVID showed reduction in both all-cause mortality and arrhythmic death while the two smaller trials showed only improvement in arrhythmic death. Similarly, trials like MADIT, CABG Patch, MUSTT, MADIT-II, DINAMIT, and the IRIS trial have fine-tuned the indications for ICD in primary prevention of sudden cardiac death. Benefits of an ICD were most pronounced in those with reduced ejection fraction and 40 days or more since myocardial infarction or in those who were not immediately post revascularization. The recent VEST trial aimed to study wearable cardioverter-defibrillators (WCDs) in patients who did not have an indication for an implantable defibrillator. The arrhythmic deaths (1.6% vs. 2.4%) were not reduced by the WCD. Based on consistent reduction in arrhythmic death in all primary and secondary prevention trials, defibrillators are effective in carefully selected patients.