Abstract 2207: Value of Ventricular Stiffness Index and Ventricular-Arterial Interaction in Predicting Exercise Capacity in Patients with Nonischemic Dilated Cardiomyopathy
Increased ventricular stiffness and afterload are major contributors to the pathogenesis of heart failure. We sought to investigate whether dilated cardiomyopathy (DCM) patients have distinct ventricular elastance or ventricular-arterial interaction compared to hypertensive patients or healthy controls and they can be used to predict exercise capacity. Twenty-five patients with DCM, 25 age- and gender-matched hypertensive patients, and 25 healthy controls underwent a symptom-limited graded supine bicycle exercise echo after a comprehensive resting echo-Doppler evaluation. Left ventricular (LV) diastolic elastance (Ed, early mitral inflow to anuular velocity/stroke volume), ventricular-vascular coupling index (VVI, Ea/Ees) based on arterial elastance index (Ea, end-systolic pressure/stroke volume) to LV end-systolic elastance index (Ees, peak LV outflow tract velocity to acceleration time) and hemodynamic parameters were measured during exercise test. DCM patients had lower Ees, and higher Ed and VVI with blunted response of Ees and Ea to peak exercise than hypertensive patients or controls. In DCM patients, resting Ees correlated with contractile reserve to low grade exercise (Δsystolic mitral annular velocity to 25W. r=0.561, p=0.004) with close relationship between Ed and VVI (r=0.525, p=0.007 at rest; r=0.510, p=0.047 at 25W exercise). Resting Ed (β=−0.597, p=0.003), VVI (β=−0.523, p=0.010), and total stiffness index (Ed x VVI, β=−0.647, p=0.001) correlated with exercise duration independent of age and gender. Total stiffness index could reliably predict the impaired exercise capacity (<400 sec, 69% sensitivity and 70% specificity). DCM patients have distinct Ed and VVI, which have mutual relationship and predictive power of exercise capacity.