Supraventricular tachyarrhythmias in acute myocardial infarction.

Onset of atrial tachycardia, flutter or fibrillation occurred in 11% of 274 consecutive patients with acute myocardial infarction (AMI). Atrial tachycardia started about 24 hours and atrial flutter/fibrillation about 72 hours after onset of AMI symptoms. Left heart failure, diagnosed as pulmonary rales or frank pulmonary edema, was not more common in these patients before onset of tachyarrhythmias than among the rest of the patients. On the other hand, a notching of the P wave in lead CR-was significantly more common in the patients with atrial fibrillation (67%). In most of these cases the terminal P force in lead CR1 was not negative as in so-called left atrial enlargement. These findings suggest that atrial conduction disturbances might be a basis of atrial fibrillation in AMI.