Aims: In heart failure, a reduced exercise capacity is the prevailing symptom and an important prognostic marker of future outcome. The purpose of the study was to assess the relation of coronary flow reserve (CFR) to diastolic and systolic function in heart failure and to determine which are the limiting factors for exercise capacity.
Methods and results: Forty-seven patients with left ventricular ejection fraction (LVEF) <35 [median LVEF 31 (inter-quartile range 26-34)] underwent cardiorespiratory exercise test with measurement of VO2 peak, a dual X-ray absorptiometry scan for body composition, and a full echocardiography with measurement of LVEF using the biplane Simpson model, mitral inflow velocities, and pulsed wave tissue Doppler. Peak coronary flow velocity (CFV) was measured in the LAD, using pulsed-wave Doppler. CFR was calculated as the ratio between peak CFV at rest and during 2 min of adenosine stress. Fat-free-mass-adjusted VO2 peak correlated significantly with CFR (r = 0.48, P = 0.002), E/e' (r = -0.35, P = 0.02), and s' (r = 0.45, P = 0.001) but not with LVEF (r = 0.23, P = 0.11). CFR correlated significantly with E/e' (r = -0.46, P = 0.003) and s' (r = 0.36, P = 0.02), but not with LVEF (r = 0.18, P = 0.26). When adjusting for CFR in a multivariable linear model, s' but not E/e' remained independently associated with VO2 peak.
Conclusion: In this group of heart failure patients, VO2 peak was correlated with CFR, E/e', and s' but not with traditional measures of systolic function. CFR remained associated with VO2 peak independently of diastolic and systolic function and is likely to be a limiting factor in functional capacity of heart failure patients.
Keywords: Coronary flow reserve; Diastolic function; Exercise capacity; Heart failure; Systolic function.