Metabolic imaging by positron emission tomography early after myocardial infarction as a predictor of recovery of myocardial function after reperfusion.

Abstract

Myocardial ischemia leads to alterations in myocardial substrate metabolism that have been shown to reflect severity of ischemic injury. The purpose of this study was to correlate oxidative metabolism with recovery of contractile function in patients with acute myocardial infarction. Regional blood flow and oxidative metabolism were assessed by dynamic positron emission tomography early after myocardial infarction treated with thrombolytic therapy in 18 patients. The extent of myocardial perfusion abnormally (carbon 11-labeled acetate uptake; relative amplitude < or = 50%) was inversely correlated with the ejection fraction obtained within 8 hours of the onset of chest pain (r = -0.81; p - 0.01) but not clearly with that at follow-up 1 week later (r = 0.64; p = 0.09). Oxidative metabolism (carbon 11-labeled acetate; monoexponential clearance) was higher in periinfarct territories with early or late recovery of contractile function than in those without, but there was a large overlap in absolute values limiting the predictive power of a single measurement. Relatively preserved oxidative metabolism compared with perfusion in low-flow areas was predictive of early (day 1 to 1 week) and delayed (week 1 to beyond 1 month) recovery. Normal resting perfusion with regionally decreased oxidative metabolism predicted early recovery of contractile function. Thus in patients studied with positron emission tomography early after myocardial infarction, comparison of regional perfusion and oxidative metabolism was more predictive of recovery in contractile function than was assessment of either one alone.