Dependence of recovery of contractile function on maintenance of oxidative metabolism after myocardial infarction

Abstract

This study was performed to define the importance of maintenance of oxidative metabolism as a descriptor and determinant of the potential for functional recovery after revascularization in patients with recent myocardial infarction. In 11 patients (mean interval after infarction 6 days; 5 patients given thrombolytic therapy), positron emission tomography (PET) was performed to characterize myocardial perfusion (with oxygen-15-labeled water), glucose utilization (with fluorine-18-fluorodeoxyglucose) and oxidative metabolism (with carbon-11-acetate). Dysfunctional but viable myocardium was differentiated from nonviable myocardium by assessments of regional function before and after coronary revascularization. The impact of coronary revascularization on regional myocardial perfusion and metabolism was assessed in nine patients in whom tomography was repeated after revascularization. Before revascularization, dysfunctional but viable myocardium (19 segments) and nonviable myocardium (10 segments) exhibited relative perfusion equivalent to 74% and 63% of that of normal myocardium (33 segments), respectively (p less than 0.02). Dysfunctional but viable myocardium exhibited oxidative metabolism equivalent to 74% of that of normal myocardium (p less than 0.02). In contrast, in nonviable myocardium, oxidative metabolism was only 45% of that seen in normal (p less than 0.02) and 60% of that in reversibly dysfunctional myocardium (p less than 0.003). Regional glucose utilization (normalized to regional perfusion) in dysfunctional but viable myocardium was higher than that in normal myocardium (p less than 0.02). Nonviable myocardium exhibited lower levels of glucose utilization than did normal tissue (p less than 0.02). However, in both reversibly and persistently dysfunctional myocardium utilization of glucose normalized to relative perfusion was markedly variable.(ABSTRACT TRUNCATED AT 250 WORDS)