Left ventricular function and exercise capacity

Context: Limited information exists regarding the role of left ventricular function in predicting exercise capacity and impact on age- and sex-related differences. Objectives: To determine the impact of measures of cardiac function assessed by echocardiography on exercise capacity and to determine if these associations are modified by sex or advancing age. Design: Cross-sectional study of patients undergoing exercise echocardiography with routine measurements of left ventricular systolic and diastolic function by 2-dimensional and Doppler techniques. Analyses were conducted to determine the strongest correlates of exercise capacity and the age and sex interactions of these variables with exercise capacity. Setting: Large tertiary referral center in Rochester, Minnesota, in 2006. Participants: Patients undergoing exercise echocardiography using the Bruce protocol (N=2867). Patients with echocardiographic evidence of exercise-induced ischemia, ejection fractions lower than 50%, or significant valvular heart disease were excluded. Main Outcome Measure: Exercise capacity in metabolic equivalents (METs). Results: Diastolic dysfunction was strongly and inversely associated with exercise capacity. Compared with normal function, after multivariate adjustment, those with moderate/severe resting diastolic dysfunction (-1.30 METs; 95% confidence interval [CI], -1.52 to -0.99; P < .001) and mild resting diastolic dysfunction (-0.70 METs; 95% CI, -0.88 to -0.46; P < .001) had substantially lower exercise capacity. Variation of left ventricular systolic function within the normal range was not associated with exercise capacity. Left ventricular filling pressures measured by resting E/e′ of 15 or greater (-0.41 METs; 95% CI, -0.70 to -0.11; P = .007) or postexercise E/e′ of 15 or greater (-0.41 METs; 95% CI, -0.71 to -0.11; P = .007) were similarly associated with a reduction in exercise capacity, each in separate multivariate analyses. Individuals with impaired relaxation (mild dysfunction) or resting E/e′ of 15 or greater had a progressive increase in the magnitude of reduction in exercise capacity with advancing age (P < .001 and P = .02, respectively). Other independent correlates of exercise capacity were age (unstandardized β coefficient, -0.85 METs; 95% CI, -0.92 to -0.77, per 10-year increment; P < .001), female sex (-1.98 METs; 95% CI, -2.15 to -1.84; P < .001), and body mass index greater than 30 (-1.24 METs; 95% CI, -1.41 to -1.10; P < .001). Conclusion: In this large cross-sectional study of those referred for exercise echocardiography and not limited by ischemia, abnormalities of left ventricular diastolic function were independently associated with exercise capacity.