Dynamic 123I-HDA myocardial scintigraphy after aortocoronary bypass grafting

In an attempt to evaluate the dynamics of fatty acid metabolism after aortocoronary bypass grafting (ACBG), ten patients were investigated after ACBG by ¹²³I-HDA myocardial scintigraphy. Tracer kinetics were followed for 90 min and compared to those of 36 nongrafted patients with different underlying heart diseases, including healthy volunteers. Regional analysis and monoexponential curve fitting were used to evaluate t_1/2 (half-life of the early period of tracer elimination); biexponential curve analysis was used to calculate Ca/Cb, the ratio of a fast and a slow component of tracer elimination. Rest and stress MUGA-RNV served as discriminating parameters to discern between patient groups with normal and abnormal ventricular function. Group I (normal controls) encompassed ten patients with normal ventricular function, including three after ACBG, and group II seven patients after ACBG and with abnormal ventricular function. Group III had coronary artery disease (CAD) documented by angiography, and group IV by prior myocardial infarction (MI). Group V included patients with cardiomyopathy (CMP). Regional analysis of group II revealed no significant differences to control regions (Gr I) for t_1/2 or Ca/Cb, but showed for Ca/Cb a nonsignificant shift toward group III values. However, group II differed significantly from group III and V. Three patients with normal ventricular function after ACBG showed elimination values that were all well within the range of completely normal individuals. Thus our data support the assumption that a normal function is indicative of a normal metabolism. Following myocardial fatty acid metabolism during rest might be a helpful noninvasive tool for etiologic differentiation of disturbed ventricular function.