[Note: Diastolic dysfunction, which occurs when the left ventricle of the heart is unable to fill with normal amounts of blood, has been a factor of interest to researchers investigating post-exercise malaise in chronic fatigue syndrome (ME/CFS).]
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).
• 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 ? 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.
Source: JAMA, Jan 21, 2009;301(3):286-294. Grewal J, McCully RB, Kane GC, Lam C, Pellikka PA. Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.