Myocardial fatty-acid, glucose, and total oxidative metabolism in patients with myocardial infarction and left ventricular remodeling

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In patients with acute myocardial infarction (MI), alteration of metabolism sources is observed on left ventricular (LV) wall and LV remodeling is provoked in remote normal region in sub-acute and/or chronic phases, being related to the patients' prognosis. Accordingly, we investigated the relationships between myocardial blood flow, myocardial fatty-acid metabolism, and myocardial total oxidative metabolism in patients with MI in sub-acute phase. Furthermore, we also studied the myocardial oxidative activity in remote normal region in patients with MI and LV remodeling in chronic stage.1)We investigated myocardial fatty acid metabolism from the viewpoint of palmitate beta-oxidation using positron emission tomography (PET). The clearance rate constant of ^<11>C-acetate (acetate-Kmono) and that of ^<11>C-palmitate (palmitate-Kmono) from myocardium were calculated using a monoexponential equation in 14 patients with MI. Regional relative myocardial blood flow calculated from the initial … More distribution of ^<11>C-acetate and left ventricular (LV) wall motion were also evaluated. Maintained myocardial fatty acid beta-oxidation with better myocardial blood flow is substantial for preserving total myocardial oxidative metabolism and LV wall motion in patients with MI. The finding whether the early-phase clearance of ^<11>C-palmitate is fitted with a monoexponential curve may provide important information in the evaluation of myocardial fatty acid beta-oxidation.2)In 8 patients with MI with diabetes mellitus (DM), 10 with MI without DM, and 6 healthy volunteers, we studied the oxidative metabolism as the clearance rate constant (Kmono) of ^<11>C-acetate in remote normal region using PET. All patients with MI had single vessel coronary artery disease. Apparent LV remodeling was observed in patient with MI. Kmono in remote normal region in patients MI was significantly decreased compared with the Kmono in normal volunteers, which was obtained as a mean value of all ROIs on the LV wall. This impaired myocardial oxidative metabolism in remote normal region with LV remodeling indicates that the myocardium in such a region is not normal but damaged, and it is considered to be one of the reasons for poor prognosis of the patients having LV remodeling after MI. No significant difference was observed in Kmono in remote normal region between the patient with DM and those without DM Less