Dobutamine response and myocardial infarct transmurality: functional improvement after coronary artery bypass...

The Investigational Review Board approved the protocol, and all patients provided signed informed consent. The protocol was compliant with HIPAA. The purpose of the study was to prospectively test the hypothesis that addition of low-dose dobutamine and quantification of inotropic reserve in segments with 1%-50% infarct transmurality (IT) would improve the predictive value for functional recovery after revascularization in chronic infarction. Fifteen patients with multivessel coronary artery disease and left ventricular systolic dysfunction were enrolled prior to coronary artery bypass grafting (CABG). Late gadolinium-enhanced cardiac magnetic resonance (MR) imaging was used to assess IT. The percentage of wall thickening was measured with cine cardiac MR imaging at rest and during infusion of 10 (microg . kg(-1))/min dobutamine. Repeat cardiac MR imaging was performed 20 weeks +/- 4 (standard error) later. Functional parameters according to segment were compared before and after CABG by using F tests with repeated-measures models. In segments with 1%-50% IT, similar functional recovery was noted in those with 1%-25% or 26%-50% IT. However, in the same segments, those that improved with dobutamine to normal range demonstrated greater improvement in the percentage of wall thickening (22% +/- 4) after revascularization than those that did not (9% +/- 4) (P < .04). In 1%-50% IT, a normal dobutamine response helps differentiate segments with greater functional recovery after CABG.