Prevalence and Prognostic Significance of Exercise-Induced Nonsustained Ventricular Tachycardia in Asymptomatic Volunteers: BLSA (Baltimore Longitudinal Study of Aging)

Abstract

This study sought to determine the clinical predictors and prognostic significance of exercise-induced nonsustained ventricular tachycardia (NSVT) in a large population of asymptomatic volunteers. Prior studies have reported variable risk associated with exercise-induced ventricular arrhythmia. Subjects in the BLSA (Baltimore Longitudinal Study of Aging) free of known cardiovascular disease who completed at least 1 symptom-limited exercise treadmill test between 1977 and 2001 were included. NSVT episodes were characterized by QRS morphology, duration, and rate. Subjects underwent follow-up clinical evaluation every 2 years. The 2,099 subjects (mean age: 52 years; 52.2% male) underwent a mean of 2.7 exercise tests, in which 79 (3.7%)developed NSVT with exercise on at least 1 test. The median duration of NSVT was 3 beats (≤5 beats in 84%), and the median rate was 175 beats/min. Subjects with (vs. without) NSVT were older (67 ± 12 years vs. 51±17 years, p< 0.0001) and more likely to be male (80% vs. 51%, p< 0.0001) and to have baseline electrocardiographic abnormalities (50% vs. 17%, p< 0.0001) or ischemic ST-segment changes with exercise (20% vs. 10%, p= 0.004). Over a mean follow-up of 13.5 ± 7.7 years, 518 deaths (24.6%) occurred. After multivariable adjustment for age, sex, and coronary risk factors, exercise-induced NSVT was not significantly associated with total mortality (hazard ratio: 1.30; 95% confidence interval: 0.89 to 1.90; p= 0.17). Exercise-induced NSVT occurred in nearly 4% of this asymptomatic adult cohort. This finding increased with age and was more common in men. After adjustment for clinical variables, exercise-induced NSVT did not independently increase the risk of total mortality.