Cardiac power during exercise and the risk of stroke in men

Abstract

Background and Purpose - Low maximal oxygen uptake (VO2max) has been shown to predict the risk of stroke. However, VO2max does not take into account the differences in cardiac afterload between subjects. The aim of this study was to examine the relationship of exercise cardiac power (ECP), defined as a ratio of VO2max with peak systolic blood pressure (SBP) during exercise, with the risk for stroke. Methods - Population-based cohort study with an average follow-up of 12 years from eastern Finland. A total of 1761 men with no history of stroke or coronary heart disease at baseline participated. Among these men, 91 strokes occurred, of which 69 were attributable to ischemic causes. Results - The relative risk of any stroke in men with low ECP (<10.3 mL/mm Hg) was 2.7 (95% CI, 1.2 to 6.0; P=0.01; P=0.02 for the trend across the quartiles), and the relative risk for ischemic stroke was 2.7 (95% CI, 1.1 to 7.0; P=0.03; P=0.04 for trend across the quartiles) compared with men having high ECP (>14.3 mL/mm Hg) during exercise after adjusting for age, examination year, cigarette smoking, alcohol consumption, body mass index, diabetes, serum total cholesterol level, energy expenditure of physical activity, exercise-induced myocardial ischemia, and the use of antihypertensive medication. After further adjustment for resting SBP, results were statistically nonsignificant. Conclusions - Low ECP provides noninvasive and easily available measure for stroke risk. One of the most potential explanations for the association between ECP and the increased risk of stroke is an elevated afterload and peripheral resistance indicated by elevated SBP. © 2005 American Heart Association, Inc.