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

Twenty-four hour ambulatory electrocardiographic tape recording was carried out four times within the first six months after an acute myocardial infarction in 100 consecutive patients below the age of 70 years.Sixty-four episodes of ventricular tachycardia were observed on 23 tapes recorded from 19 patients.Six episodes were accompanied by symptoms; syncope occurred twice.Ventricular tachycardia was rare during sleep, and occurred more commonly after discharge than in hospital.Forty-seven per cent of the episodes were 10 or more beats in length, and the maximum heart rate in each varied from 108 to 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 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 first 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 six-month follow-up period; none had ventricular tachycardia, which was seen in two of the four patients who reinfarcted.The investigation shows that ventricular tachycardia occurs frequently during the first six months after a myocardial infarction, but it is usually self-limiting and asymptomatic, whether patients are or are not receiving antiarrhythmic treatment.