Paroxysmal ventricular tachycardia during repeated 24-hour ambulatory electrocardiographic monitoring of postmyocardial infarction patients.

Abstract

Ambulatory ECG tape recording (24 h) was carried out 4 times within the first 6 mo. after an acute myocardial infarction in 100 consecutive patients > 70 yr. Episodes (64) of ventricular tachycardia were observed on 23 tapes recorded from 19 patients. Six episodes were accompanied by symptoms and syncope occurred twice. Ventricular tachycardia was rare during sleep and occurred more commonly after discharge than in the hospital. Episodes (47%) were 10 or more beats in length and the maximum heart rate in each varied from 108-300/min. The heart rate immediately beforehand was 89/min .+-. 15 (SD) and was not constant in any individual experiencing repeated attacks. Episodes, even longer ones, were not followed by significant tachycardia. Patients with ventricular tachycardia or ventricular fibrillation in the coronary care unit were significantly more likely to develop ventricular tachycardia later (P < 0.05), and ventricular tachycardia was more frequent after transmural than subendocardial infarction (P < 0.05). In the hospital, the group with ventricular tachycardia was significantly more likely to have a sleeping heart rate of 80/min or more (P < 0.05). The mean prematurity index (RR''/QT) of the 1st complex of each episode of ventricular tachycardia was 1.41 .+-. 0.28 (SD) and no episode was triggered by the R of T phenomenon, which was seen 43 times. Four patients died suddenly in the 6 mo. follow-up period; none had ventricular tachycardia which was seen in 2 of the 4 patients who reinfarcted. Ventricular tachycardia occurs frequently during the first 6 mo. after a myocardial infarction, but it is usually self-limiting and asymptomatic, whether patients are or are not receiving antiarrhythmic treatment.