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

OBJECTIVES This study investigated the prognostic importance of measured peak oxygen intake ((V) over dot O-2peak) in women with known coronary heart disease referred for outpatient cardiac rehabilitation. BACKGROUND Exercise 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 (V) over dot O-2peak, the most accurate measure of exercise capacity. METHODS A 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 under-went 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. RESULTS We recorded 95 cardiac deaths and 209 all-cause deaths. Measured (V) over dot O-2peak was an independent predictor of risk, values : greater than or equal to 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 (V) over dot O-2peak was 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). CONCLUSIONS As in men, measured (V) over dot O-2peak is a strong independent predictor of cardiac mortality in women referred for cardiac rehabilitation. (J Am Coll Cardiol 2003;42:2139-43) (C) 2003 by by the American College of Cardiology Foundation.