Usefulness of the Evaluation of Isovolumic and Ejection Phase Myocardial Signals during Stress Echocardiography in Predicting Exercise Capacity in Heart Failure Patients

Abstract

To assess changes of systolic function using tissue Doppler imaging (TDI) during stress echocardiography and its impact on exercise capacity in heart failure (HF) patients (pts). 80 pts (65 male), mean age of 59.3 +/- 10.9 years, NYHA class 1.95 +/- 0.8, left ventricle ejection fraction (LVEF) 27.2 +/- 9.5 (10-45%). The etiology of HF was ischemic (ICM) in 50 pts and dilated cardiomyopathy (DCM) in 30 pts. Peak myocardial velocity (IVV) and acceleration (IVA) during isovolumic contraction and peak myocardial velocity during ejection phase (S') were measured at baseline and peak exercise during semi-supine stress-echo (20 Watts, 2-min increments). Concurrently peak oxygen uptake (VO(2) peak) was measured. Rest values of analyzed parameters were comparable in groups according to etiology of HF and physical capacity. However, peak stress parameters mainly S' were significantly higher in the DCM group and the group with better VO(2) peak. The best correlation with exercise capacity was S' at peak stress (r = 0.66; p < 0.0001). The most useful parameter for identifying severe exercise intolerance, VO(2) peak < 14 ml/kg/min, was S' with an area under ROC curve of 0.82 +/- 0.05 (95% CI 0.71-0.89). The cutoff of 5.75 cm/s for S' at peak stress showed a sensitivity of 61% with a specificity of 96%. The evaluation of systolic function by means of TDI instead of LVEF shows more clearly that systolic function is at least partly responsible for exercise tolerance in HF. Assessment of echocardiographic systolic parameters at peak stress provides more accurate information about exercise capacity in HF pts.