Incidence and description of accelerated ventricular rhythm complicating acute myocardial infarction.

One hundred and nineteen episodes of accelerated ventricular rhythm (less than 125/min) were noted in 37 patinets with acute myocardial infarction during a 1 year period. The incidence was 12.7 per cent. Twenty-seven episodes of fast ventricular tachycardia (less than 125/min) were noted in 16 of these patients. Eighteen patients had anterior myocardial infarction and 19 inferior myocardial infarction. The mechanism of onset of accelerated ventricular rhythm was classified as escape in 65 episodes. Ventricular premature beats were noted close to episodes of accelerated ventricular rhythm in 31 patients and fast ventricular tachycardia in 14 patients. The morphology of accelerated ventricular rhythm was similar to the ventricular premature beats in 27 patients and similar to the fast ventricular tachycardia in 12. In 11 patinets the morphology of ventricular premature beats, accelerated ventricular rhythm and fast ventricular tachycardia were all the same. In six patients the coupling time of the ventricular premature beats and the onset of the accelerated ventricular rhythm were the same. In seven patients the morphology of the accelerated ventricular rhythm and fast ventricular tachycardia were the same, and the rate of the accelerated ventricular rhythm was exactly half that of the fast ventricular tachycardia. There were three deaths due to shock and heart failure. Three episodes of fast ventricular tachycardia progressed to ventricular fibrillation and were successfully cardioverted. It is concluded that accelerated ventricular rhythm and fast ventricular tachycardia were all the same. In six patients the coupling time of the ventricular premature beats and the onset of the accelerated ventricular rhythm were the same. In seven patients the morphology of the accelerated ventricular rhythm and fast ventricular tachycardia were the same, and the rate of the accelerated ventricular rhythm was exactly half that of the fast ventricular tachycardia. There were three deaths due to shock and heart failure. Three episodes of fast ventricular tachycardia progressed to ventricular fibrillation and were successfully cardioverted. It is concluded that accelerated ventricular rhythm is a relatively common complication of both anterior and inferior myocardial infarction. The high incidence of concomitant fast ventricular tachycardia, the frequency of ventricular premature beats with similar morphology and coupling time, and the instances of two arrhythmias having common rate multiples, suggest that at least in some instances accelerated ventricular rhythm may represent an ectopic focus with exit block.