Cardiorespiratory fitness and nonfatalcardiovascular events: A population-based follow-up study

Abstract

To examine the prognostic value of cardiorespiratory fitness (CRF) with risk of first major nonfatal myocardial infarction (MI), stroke, and heart failure (HF) events. Cardiorespiratory fitness, as measured by maximal oxygen uptake, was assessed at baseline in a prospective cohort of 2,089 men aged 42 to 61years. During a mean (SD) follow-up of 19.1(8.4) years, 522 nonfatal acute MI events, 198 acute all-cause nonfatal stroke events, and 221 nonfatal HF events were recorded. The hazard ratio per 1-metabolic-equivalent increase in CRF was 0.93 (95% CI 0.88-0.97) for nonfatal MI, 0.94 (95% CI0.87-1.01) for nonfatal stroke, and 0.84 (95% CI 0.78-0.91) for nonfatal HF events after adjustment for cardiovascular risk factors (age, systolic blood pressure, body mass index, history of cardiovascular disease, diabetes, smoking, alcohol use, serum creatinine, low-density lipoprotein levels, physical activity, and socioeconomic status). Further adjustment for left ventricular hypertrophy and resting heart rate did not attenuate these associations. Addition of CRF to conventional cardiovascular disease risk factors significantly improved both discrimination (C index) and category free net reclassification index (cf-NRI) for nonfatal MI (change in C index, 0.015 [95% CI 0.010-0.020] and change in cf-NRI 0.27, P<.01) and HF (change in C index 0.040 [95% CI 0.010-0.060] and change in cf-NRI 0.88, P<.01). In this Finnish population, there is a strong, inverse, and independent association between CRF and acute nonfatal MI and HF risk.