Abstract 2560: Prognostic Significance of Exercise-induced Non-sustained Ventricular Tachycardia in Asymptomatic Volunteers: The Baltimore Longitudinal Study of Aging
Background: Prior studies report variable risk associated with exercise-induced ventricular ectopic beats. We determined the clinical predictors and prognostic significance of exercise-induced non-sustained ventricular tachycardia (NSVT) in a large population of asymptomatic volunteers.
Methods: Subjects in the Baltimore Longitudinal Study of Aging free of known cardiovascular (CV) disease and who completed at least one symptom-limited exercise treadmill test between 1977 and 2001 were included. ECGs were coded by Minnesota code. NSVT episodes were characterized by QRS morphology, duration, and rate. Subjects had clinical evaluation every two years. Vital status was verified by Social Security Death Index.
Results: Final cohort included 2234 subjects (mean age 51.7 yrs, 52.6% male), of whom 81 (3.6%) developed NSVT with exercise. Mean follow-up was 12.4±7.4 yr. NSVT was polymorphic in 60%, with median duration of 3 beats (84% 5 beats or fewer) and median rate of 175 bpm. Subjects with (vs. without) NSVT were older (67±12 yr vs. 51±17 yr, adjusted OR 1.04 per year, p<0.0001), and more likely to be male (80% vs 52%, OR 4.42, p<0.0001), and to have baseline ECG conduction abnormalities (OR 1.86, p=0.03) or ischemic ST segment changes with exercise (OR 1.82, p=0.03). Unadjusted total mortality was higher in subjects with exercise-induced NSVT (Table⇓). However, after multivariable adjustment for age, sex, and coronary risk factors, exercise-induced NSVT was not significantly associated with total mortality, CV mortality, or major coronary events (coronary death or MI).
Conclusions: Exercise-induced NSVT occurred in nearly 4% of this asymptomatic adult cohort. This finding increases with age and is more common in males and in subjects with baseline ECG abnormalities or exercise-induced ischemic ECG changes. After adjustment for potential confounders, exercise-induced NSVT did not increase risk of total mortality, CV mortality, or major coronary events.