Prevalence and significance of postexercise hypotension in apparently healthy subjects

Although a decrease in systolic blood pressure (BP) occurring during treadmill exercise is often a sign of severe left ventricular dysfunction, the prevalence and significance of postexertional hypotension is unclear. The postexercise systolic BP response to maximal treadmill exercise was analyzed in 781 asymptomatic volunteers, aged 21 to 96 years (mean 51 ± 16) from the Baltimore Longitudinal Study on Aging. Fifteen subjects (1.9%) had a postexercise decrease in systolic BP of at least 20 mm Hg from preexercise sitting values, to a level of 90 mm Hg or less. The prevalence of postexercise hypotension was 3.1% (14 of 449) in subjects younger than 55 years, but only 0.3% (1 of 332) in those older than 55 (p < 0.01). Before exercise these 15 subjects demonstrated a slight orthostatic decrease in systolic BP of -1.7 ± 4.8 mm Hg compared with an increase of 5.3 ± 5.1 mm Hg in age-matched control subjects (p < 0.001). The lowest systolic BP averaged 78 ± 9 mm Hg (range 62 to 90) and occurred between 4 and 9 minutes after exercise in 80% of cases. All but 3 episodes were symptomatic, with dizziness dominant. In only 2 subjects was the hypotension associated with vagal symptoms and bradycardia. Compared with control subjects, subjects with postexercise hypotension had higher maximal heart rates (184 ± 15 vs 173 ± 11 beats/min, p < 0.05), but showed no difference in exercise tolerance or systolic BP at submaximal or maximal effort. Postexercise ST-segment abnormalities suggesting ischemia occurred in one-third of the hypotensive subjects but none of the control subjects (p < 0.05). No subject with hypotension experienced cardiovascular morbidity or mortality over a follow-up period averaging 4 years. Thus, in a general population, hypotension after treadmill exercise occurs primarily in younger persons with high maximal heart rates. It may be a cause for an ischemic electrocardiographic response but appears to have a benign prognosis.