Clinical significance of ventricular tachycardia (3 beats or longer) detected during ambulatory monitoring after myocardial infarction.

Six-hour ECG recordings were performed every four months during follow-up periods (4-48 months) in 915 patients less than 66 years of age who survived the hospital phase of myocardial infarction. One hundred ninety-nine episodes of ventricular tachycardia (VT) were identified in 66 patients. Most patients (74%) had only one episode of VT. In 47% of the patients, the longest run of VT consisted of three ventricular premature beats in a row. A double set of control patients (N = 132) was assembled by matching each VT patient according to sex, admission date and VT recording date. The VT and control patients were similar in most clinical characteristics. However, VT patients had more severe cardiac disease (P < 0.05) and more evidence of ventricular irritability (P < 0.01) than their