Abnormal diastolic filling patterns in chronic heart failure--relationship to exercise capacity

Abnormal patterns of diastolic ventricular filling are well recognized in chronic heart failure, but their relationship to the severity of heart failure is not known. The present study evaluates the relationship of diastolic filling indices to the severity of heart failure and to exercise capacity. In 40 patients with chronic heart failure secondary to ischaemic left ventricular impairment, exercise capacity was measured as peak oxygen consumption (VO2max) by progressive treadmill exercise. Left ventricular function was assessed by M-mode and Doppler echocardiographic indices. Peak aortic velocity correlated weakly with VO2max (R = +0.38, P less than 0.05). VO2max did not correlate with other systolic indices, including mean aortic acceleration, time to peak velocity, or isovolumic contraction time. VO2max correlated with the mitral inflow E/A ratio (R = -0.57, P less than 0.005) and with the Doppler estimate of isovolumic relaxation time (R = -0.48, P less than 0.01). Two distinct patterns of diastolic filling were observed: subjects with mild-to-moderate heart failure (NYHA grade II, VO2max 15-20 ml.kg-1.min-1) had abnormally low E/A ratios and long isovolumic relaxation times, whereas those with severe heart failure (NYHA grade III-IV, VO2max less than 12 ml.kg-1.min-1) had abnormally high E/A ratios and short isovolumic relaxation times. Different patterns of abnormal diastolic filling with different degrees of severity of heart failure may explain some of the previous controversy as to the prevalence of abnormal diastolic function in chronic heart failure. Exercise capacity in chronic heart failure appears more closely related to abnormalities of diastolic filling pattern than to indices of systolic function.