Early atrial arrhythmias in acute myocardial infarction. Role of the sinus node artery.

We studied atrial arrhythmias during the first 12 h of admission to the hospital in 266 consecutive patients with acute myocardial infarction who subsequently underwent coronary angiography. Ten patients developed atrial fibrillation, one atrial flutter, and one supraventricular tachycardia. Another five developed sinus dysrhythmias. All of the above patients had an acute inferior myocardial infarction, and in 10 of the 12 patients with supraventricular arrhythmias and in four of five with sinus dysrhythmias, the origin of the sinus node artery started just after an occluded right coronary or left circumflex artery or was involved in the occlusion. Thus, ischemia of the sinus node due to coronary occlusion proximal to the origin of the sinus node artery was a likely cause of these arrhythmias.