Measures to Prevent Sudden Cardiac Death Early after Acute Myocardial Infarction

Abstract

Of all patients having an acute myocardial infarction (AMI), 25-35% will die of sudden cardiac death (SCD) due to ventricular fibrillation (VF) before seeking medical attention. For those who reach the hospital, prognosis is considerably better and has improved over the years. Reperfusion therapy, which is superior with primary percutaneous coronary intervention (PCI) versus thrombolysis, has made the difference. There is currently overwhelming evidence in favor of an expanded role and use of primary PCI in an attempt to reduce the risk of SCD early and late after an AMI. In-hospital SCD due to acute (<48 hours) ventricular tachyarrhythmias is manageable, with either preventive measures or electrical cardioversion; these arrhythmias do not portend an adverse late outcome. Secondary prevention of SCD in the early post-AMI period is accomplished via an implantable cardioverter defibrillator (ICD) for sustained ventricular arrhythmias emerging >48 hours after an AMI, not due to reversible or correctable causes. However, the major challenge remains that of primary prevention of SCD between the 48-hour period and the first 40 days post-AMI for patients who have low left ventricular ejection fraction (LVEF) and are not candidates for an ICD according to current guidelines. Two ICD trials (DINAMIT and IRIS) have shown no benefit of ICD in this early period. Two recent documents may provide direction as to how to bridge this early gap. The first relates to the “appropriate use criteria for ICDs and cardiac resynchronization therapy (CRT) ICDâ€, and the second is an “expert consensus statement on the use of ICD therapy in patients who are not included or not well represented in clinical trialsâ€.