Sudden cardiac death (SCD) due to ventricular fibrillation (VF) remains a principal cause of mortality in acute myocardial infarction (AMI). Primary VF, which occurs in the absence of heart failure, may occur as the initial presentation of AMI or at any subsequent time following hospital admission. For decades, conventional wisdom has held that patients with primary VF in the early postinfarct period (within 24–48 h) fared better in the long term than those who experience VF later on in their course. This makes intuitive sense—the heart that was ‘too young to die’ did not have established necrosis, and provided that resuscitation occurred promptly, could still serve the patient well for years to come.

The first data to support this concept came in the pre-fibrinolytic era. In a study of 301 patients suffering from cardiac arrest due to VF in the prehospital setting, 101 patients were successfully defibrillated and survived to hospital admission.1 In those in whom VF or ventricular tachycardia (VT) recurred in hospital (57%), it usually did so within the first 24 h (83%). The majority of these patients died in hospital, but of the 42 patients who were discharged alive, 60% returned to prearrest status and the overall mean survival of discharged patients was over 1 year. Although only 35% of these patients were ultimately diagnosed with AMI, an almost equal number were diagnosed with myocardial ischaemia and it is likely that an acute coronary syndrome, as defined by contemporary standards, was an inciting event for a larger proportion of these patients. It is also likely that many of these patients did not suffer from primary VF and belonged to a much higher risk category due to pre-existing coronary …