Head-to-head comparison of indices of left ventricular contractile reserve assessed by high-dose dobutamine stress echocardiography in idiopathic dilated cardiomyopathy: five-year follow up

OBJECTIVE: To compare head to head the indices of left ventricular contractile reserve assessed by high-dose dobutamine in the five-year prognosis of patients with idiopathic dilated cardiomyopathy. DESIGN AND SETTING: Prospective study in a tertiary care centre. PATIENTS: 63 consecutive patients with idiopathic dilated cardiomyopathy. INTERVENTIONS: High-dose dobutamine stress echocardiography was performed in progressive stages lasting 5 min each. Wall motion score index, ejection fraction, cardiac power output and end systolic pressure to volume ratio were evaluated as indices of left ventricular contractility. MAIN OUTCOME MEASURE: Five-year cardiac mortality. RESULTS: During the follow up of 59 patients, 27 (45.8%) died of cardiac causes. According to Kaplan-Meier and receiver operating characteristic analyses all indices of contractile reserve differentiated patients with respect to cardiac death. Wall motion score index achieved the best separation (log rank 21.75, p < 0.0001, area under the curve 0.84), followed by change in ejection fraction (log rank 11.25, p = 0.0008, area under the curve 0.79), end systolic pressure to volume ratio (log rank 14.32, p = 0.0002, area under the curve 0.75) and cardiac power output (log rank 9.84, p = 0.0017, area under the curve 0.71). Cox's regression model identified wall motion score index as the only independent predictor of cardiac death. CONCLUSIONS: These data show that all examined indices of left ventricular contractile reserve are predictive of five-year prognosis, but change in wall motion score index may have the greatest prognostic potential.