Peak oxygen intake and cardiac mortality in women referred for cardiac rehabilitation

Abstract

ObjectivesThis study investigated the prognostic importance of measured peak oxygen intake (V̇O2peak) in women with known coronary heart disease referred for outpatient cardiac rehabilitation. BackgroundExercise capacity is a powerful predictor of prognosis in men with known or suspected coronary disease. Similar findings are described in women, but fewer studies have utilized measured V̇O2peak, the most accurate measure of exercise capacity. MethodsA single-center design took data from 2,380 women, age 59.7 ± 9.5 years (1,052 myocardial infarctions, 620 coronary bypass procedures, and 708 with proven ischemic heart disease), who underwent cardiorespiratory exercise testing. They were followed for an average of 6.1 ± 5 years (median 4.5 years, range 0.4 to 25 years) until cardiac and all-cause death. ResultsWe recorded 95 cardiac deaths and 209 all-cause deaths. Measured V̇O2peakwas an independent predictor of risk, values ≥13 ml/kg/min (3.7 multiples of resting metabolic rate) conferring a 50% reduction in cardiac mortality (hazard ratio [HR] 0.5, p = 0.001). Considered as a continuous variable, a 1 ml/kg/min advantage in initial V̇O2peakwas associated with a 10% lower cardiac mortality. Adverse predictors were diabetes (HR 2.73, p = 0.0005) and antiarrhythmic therapy (HR 3.93, p = 0.0001). ConclusionsAs in men, measured V̇O2peakis a strong independent predictor of cardiac mortality in women referred for cardiac rehabilitation.