CARDIOVASCULAR MEDICINE 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 highdose 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.