Chronotropic Response to Exercise Testing and the Risk of Stroke

Although the chronotropic response to exercise testing, defined as an inadequate heart rate response to incremental exercise to volitional fatigue, is associated with adverse cardiovascular outcomes, it remains unclear whether this response is related to the future risk of cerebrovascular events. We tested the hypothesis that the chronotropic response to exercise is associated with an increased risk of stroke in a general population. This prospective study was based on a population sample of 2,036 men aged 42 to 60 years in the Kuopio Ischemic Heart Disease cohort study. Chronotropic response to exercise was defined as the percentage of chronotropic index ([maximum heart rate - resting heart rate] / [220 - age - resting heart rate] × 100). Incident strokes were obtained from the Finnish national hospital discharge registry. During a median 27-year follow-up, 343 incident stroke (289 ischemic and 66 hemorrhagic) events occurred. Twelve events were diagnosed as both ischemic and hemorrhagic stroke. Comparing the bottom versus top quintile of chronotropic reserve, there was an increased risk of stroke (hazard ratio [HR] 1.73, 95% confidence Interval [CI]: 1.09 to 2.75) and ischemic stroke (HR 1.72, 95% CI, 1.04 to 2.85), but not hemorrhagic stroke (HR 2.23, 95% CI, 0.77 to 6.46) in analyses that adjusted for potential risk factors. These results suggest that an impaired chronotropic response to exercise is independently associated with a higher risk of total and ischemic stroke events in middle-aged men. The role of chronotropic incompetence during exercise testing as a potential prognostic indicator for stroke risk needs further investigation.