Idioventricular Rhythm in Acute Myocardial Infarction

An ectopic ventricular rhythm (IVR) with a rate of 60 to 100/min was detected in 36 of 100 consecutive patients with acute myocardial infarction by constant monitoring of the electrocardiogram. This mechanism was not apparent clinically and was usually transient, lasting 4 to 30 beats. It was frequently associated with inferior myocardial infarction and usually occurred during sinus bradycardia or the slow phase of sinus arrhythmia. Unlike true paroxysmal ventricular tachycardia (PVT), IVR did not progress to ventricular fibrillation and did not influence the prognosis adversely. Recognition of IVR is important in order to avoid unnecessary and perhaps dangerous treatment with cardiosuppressive drugs and electrical cardioversion.