Prognostic significance of the dobutamine echocardiography test in idiopathic dilated cardiomyopathy

Dobutamine stress echo provides potentially useful information on idiopathic dilated cardiomyopathy (IDC). From February 1, 1997, to October 1, 1999, 186 patients (131 men and 55 women, mean age 56 ± 12 years) with IDC, ejection fraction <35%, and angiographically normal coronary arteries were studied by high-dose (up to 40 μ/kg/min) dobutamine echo in 6 centers, all quality controlled for stress echo reading. In all patients, wall motion score index (WMSI) (from 1 = normal to 4 = dyskinetic in a 16- segment model of the left ventricle) was evaluated by echo at baseline and peak dobutamine. One hundred eighty-four patients were followed up (mean 15 ± 13 months) and only cardiac death was considered as an end point. There were 29 cardiac deaths. Significant parameters for survival prediction at univariate analysis are: ΔWMSI (chi-square 20.1; p <0.0000), New York Heart Association (NYHA) class (chi-square 17.57; p <0.0000), rest ejection fraction (chi-square 10.41; p = 0.0013), angiotensin-converting enzyme inhibitors (chi-square 8.23; p = 0.0041), and hypertension (chi-square 8.08, p = 0.0045). In the multivariate stepwise analysis only ΔWMSI and NYHA were independent predictors of outcome (ΔWMSI = hazard ratio 0.02, p <0.0000; NYHA class = hazard ratio 3.83, p <0.0000). Kaplan-Meier survival estimates showed a better outcome for patients with a large inotropic response (ΔWMSI ≥0.44, a cutoff identified by receiver-operating characteristic curves analysis) than for those with a small or no myocardial inotropic response to dobutamine (93.6% vs 69.4%, p = 0.00033). Thus, in patients with IDC, an extensive contractile reserve identified by high-dose dobutamine stress echocardiography is associated with a better survival.