Background: Whether echo-Doppler-derived index of ventricular elastance or ventriculoarterial interaction can reliably reflect circulatory efficiency in various conditions was investigated in the present study and whether they can be helpful in predicting exercise capacity in patients with dilated cardiomyopathy (DCM). Methods and Results: The 25 patients with DCM, 25 age- and gender-matched hypertensive patients, and 25 marathon runners underwent symptom-limited graded supine bicycle exercise echocardiography after resting echo-Doppler evaluation. Echo-Doppler-derived left ventricular (LV) diastolic elastance index (Ed), ventricular-vascular coupling index (10 × Ea/Ees), based on arterial elastance index (Ea) to LV end-systolic elastance index (Ees), and hemodynamic parameters were measured during rest and exercise. DCM patients had lower Ees, higher Ed and Ea/Ees with blunted exercise responses of Ees than the other groups, and the hypertensive patients had lower Ees and ΔEes compared with the marathon runners. Resting Ed, Ea/Ees, and total stiffness index (10 × Ed × Ea/Ees) correlated with exercise duration independent of age and gender. A stiffness index of 0.8 could reliably predict impaired exercise capacity. Conclusions: Echo-derived elastance is predictive of exercise capacity in patients with DCM. (Circ J 2009; 73: 1683-1690)