PREVALENCE AND PROGNOSTIC-SIGNIFICANCE OF EXERCISE-INDUCED SUPRAVENTRICULAR TACHYCARDIA IN APPARENTLY HEALTHY-VOLUNTEERS

The prevalence, characteristics, and prognostic significance of suprav entricular tachycardia (SVT) occurring during maximal treadmill exerci se testing were examined in 843 male and 540 female asymptomatic volun teers aged 20 to 94 years from the Baltimore Longitudinal Study of Agi ng who underwent exercise testing a mean of 2.3 times between 1977 and 1991, Exercise-induced SVT occurred during a) least 1 test in 51 men (6.0%) and 34 women (6.3%), p = NS for gender. The 85 subjects with ex ercise-induced SVT were significantly older than tile 1,298 free from this arrhythmia (66.0 +/- 13.5 vs 49.7 +/- 18.0 years, respectively, p < 0.001). The prevalence of SVT increased with age in men (p < 0.001) but not in women. Ninety-eight percent of the 141 discrete episodes o f exercise-induced SVT were paroxysmal SVT, with heart rates varying f rom 105 to 290 beats/min (mean 186.3 +/- 43.3); only 16% were > 10 bea ts in duration and only 4% of subjects were symptomatic. Nearly half ( 44%) of SVT episodes occurred at peak effort. Coronary risk factors, e chocardiographic left atrial size (3.3 +/- 6.7 vs 3.3 +/- 0.6 cm), and the prevalence of exercise-induced ischemic ST-segment depression (11 % vs 13%) were similar in 85 subjects with SVT and 170 control subject s matched for age and sex, Although the incidence of cardiac events (a ngina pectoris, nonfatal myocardial infarction, cardiac syncope, and c ardiac death) was not significantly different between subjects (6%) an d control group (10%) over a mean follow-vp period of 5.7 +/- 3.9 year s, 10% of subjects and 2% of controls subsequently developed atrial fi brillation or paroxysmal SVT, p < 0.05 by life-table analysis. Thus, e xercise-induced SVT in apparently healthy volunteers is usually limite d to short, asymptomatic runs occurring near peak exercise in predomin antly older persons, is unassociated with standard coronary risk facto rs or exercise-induced myocardial ischemia, and does not portend incre ased cardiovascular mortality or coronary events, but does appear to p redict a higher incidence of spontaneous supraventricular tachyarrhyth mia over the next several years.