Low-dose dobutamine responsiveness in idiopathic dilated cardiomyopathy: relation to exercise capacity and clinical outcome

Open Access
Publisher Website
Google Scholar
Abstract
Aims To evaluate myocardial contractile reserve using low-dose dobutamine echocardiography in patients with chronic heart failure secondary to idiopathic dilated cardiomyopathy stratified by peak exercise oxygen consumption (VO2). Methods and Results Sixty clinically stable patients (56±11 years; 45 males) with idiopathic cardiomyopathy and NYHA class I to III symptoms of heart failure were studied and followed-up for 13±3 months. All patients underwent cardiopulmonary exercise testing and low-dose dobutamine. The dobutamine infusion protocol consisted of an initial dose of 2·5μ.kg−1per 3min, increasing by 2·5μ.kg−1per min every 3min; the maximal dose was 10μ.kg−1per min. The end-systolic volume index, left ventricular ejection fraction and cardiac output were measured at baseline and peak dobutamine dose and their change calculated as ((peak dose value-baseline value)/baseline value]×100. Ten normal subjects with normal left ventricular function and no coronary artery lesions served as a control group to compare low-dose dobutamine results. All analysed echocardiographic variables either at baseline or following dobutamine infusion were significantly lower in patients with chronic heart failure as a whole compared to the control group. When the patients were grouped according to Weber's classification, a statistically significant decrease in percentange changes in end-systolic volume index (ρ=−0·77;PPP20ml.kg−1.min−1), 18·6±8% in class B (peak VO2between 16 and 20ml.kg.min−1), and only 6·4±6% in class C (peak VO2between 10 and 16ml.kg−1.min−1) patient groups. At multivariate analysis, only the percentage change in end-systolic volume index was significantly associated with a peak VO2−1.min−1(P=0·006). During the follow-up, 17 patients had events (15 readmissions for worsening heart failure and two deaths). At multivariate analysis, only the percentage change in end-systolic volume index was significantly associated with the occurrence of events (P=0·003). The area under the receiver operating characteristic curve for percentage change in end-systolic volume index was not significantly different from that for peak VO2(0·86±0·04 vs 0·80±0·06;P:ns). Conclusion This study indicates that in patients with chronic heart failure secondary to idiopathic cardiomyopathy, the cardiac response to low-dose dobutamine, as assessed by echocardiography, is correlated with peak VO2, an objective and accurate measure of the severity of the disease and clinical outcome.

This publication has 0 references indexed in Scilit: