Relative peak exercise oxygen pulse is related to sudden cardiac death, cardiovascular and all-cause mortality in middle-aged men

Background: Preliminary evidence suggests that peak exercise oxygen pulse – peak oxygen uptake/heart rate-, a variable obtained during maximal cardiopulmonary exercise testing and a surrogate of stroke volume, is a predictor of mortality. We aimed to assess the associations of peak exercise oxygen pulse with sudden cardiac death, fatal coronary heart disease and cardiovascular disease and all-cause mortality. Design: A prospective study. Methods: Peak exercise oxygen pulse was assessed in a maximal cycling test at baseline in 2227 middle-aged men of the Kuopio Ischaemic Heart Disease cohort study using expired gas variables and electrocardiograms. Relative peak exercise oxygen pulse was obtained by dividing the absolute value by body weight. Results: During a median follow-up of 26.1 years 1097 subjects died; there were 220 sudden cardiac deaths, 336 fatal coronary heart diseases and 505 fatal cardiovascular diseases. Relative peak exercise oxygen pulse (mean 19.5 (4.1) mL per beat/kg/10²) was approximately linearly associated with each outcome. Comparing extreme quartiles of relative peak exercise oxygen pulse, hazard ratios (95% confidence intervals) for sudden cardiac death, fatal coronary heart disease and cardiovascular disease, and all-cause mortality on adjustment for cardiovascular risk factors were 0.55 (0.36–0.83), 0.58 (0.42–0.81), 0.60 (0.46–0.79) and 0.59 (0.49–0.70), respectively (P < 0.001 for all). The hazard ratios were unchanged on further adjustment for C-reactive protein and the use of beta-blockers. The addition of relative peak exercise oxygen pulse to a cardiovascular disease mortality risk prediction model significantly improved risk discrimination (C-index change 0.0112; P = 0.030). Conclusion: Relative peak exercise oxygen pulse measured during maximal exercise was linearly and inversely associated with fatal cardiovascular and all-cause mortality events in middle-aged men. In addition, relative peak exercise oxygen pulse provided significant improvement in cardiovascular disease mortality risk assessment beyond conventional risk factors.