CLINICAL AND ELECTROPHYSIOLOGIC CHARACTERISTICS OF EXERCISE-RELATED IDIOPATHIC VENTRICULAR-TACHYCARDIA

In 37 (70%) of 53 patients with idiopathic ventricular tachycardia (VT), episodes were mainly related to exercise (group 1). These patients were younger (33 +/- 14 vs 44 +/- 18 years, p = 0.015) and more often had dizziness during VT (71 vs 40%, p = 0.003) than the 16 patients in whom VT was not exercise-related (group 2). Patients in group 1 needed cardioversion less often to terminate the arrhythmia (4 (11%) vs 6 (40%), group 2 [p = 0.04]). VT was initiated during exercise testing in 62% of patients in group 1 but in only 1 patient in group 2 (p = 0.0004). Induction of clinical VT during programmed stimulation was observed in a similar percentage in group 1 (49%) and group 2 (50%) patients. Isoproterenol infusion facilitated the induction of VT in 9 of 20 (45%) group 1 and in 2 of 8 (25%) group 2 patients (p = not significant). After a mean follow-up of 2.9 +/- 2.5 years, 8 (22%) group 1 patients and 5 (31%) group 2 had at least 1 episode of symptomatic VT. Only 1 patient died suddenly. Class III drugs were the most useful in preventing recurrences. Beta-blocking agents were of little value in both groups. Patients with VT and a structurally normal heart have a good prognosis despite recurrences of their arrhythmia. The relation of the arrhythmia to exercise has no prognostic implications.