Prognostic significance and treatment of early ventricular arrhythmias occuring within the acute phase of myocardial infarction

The prognosis following acute myocardial infarction (MI) has improved considerably in recent decades, essentially due to the development of percutaneous coronary intervention and improved medical therapy, including administration of thrombolytic agents. However, despite these major advances, ventricular fibrillation (VF) or rapid ventricular tachycardia (VT) still occur during the acute phase of MI in 2-8% of cases. Post-MI VA is traditionally divided into two types: early VA occurs within 48 h of MI symptom onset, whereas late VA occurs over 48 h after MI. Early VA is often attributed to the transient ischaemic settings. Several studies have shown that patients who develop VF during the acute phase of MI have a higher risk of death in the short-term. In contrast, data on mid-to-long-term survival are limited and controversial. Late VA, particularly sustained monomorphic ventricular tachycardia (VT), is more frequently due to a reentrant mechanism resulting from the presence of scar tissue, and the arrhythmogenic substrate is thought to be irreversible in these patients. While consensus guidelines agree that survivors of late VA after MI should be given an implantable cardioverter-defibrillator (ICD) prior to hospital discharge, the utility of ICDs for patients experiencing early VA after MI is less deanite.