Development of myocardial microcirculation and metabolism in acute ST-elevation myocardial infarction evaluated with positron emission tomography

Background. Early reperfusion is an established therapeutic objective in acute myocardial infarction (MI). The relationship of regional myocardial microcirculation and metabolism toward outcome in acute human MI is not well known. Methods and Results. In 8 patients, positron emission tomography (PET) was performed with oxygen 15-labeled water at 3 hours, 24 hours, and 3 weeks after the start of fibrinolytic treatment, with carbon 11 acetate at 3 hours and with fluorine 18 fluorodeoxyglucose at 24 hours and 3 weeks. Absolute quantification of perfusion and water-perfusable tissue fraction (PTF), metabolic activity, and substrate extraction in 4 regions of interest was performed. Coronary angiography was performed at 24 hours. Short-term outcome at 3 weeks was evaluated by contractile reserve with dobutamine stress echocardiography and lung water measurements with PET. Early regional perfusion, PTF, and extraction and utilization of oxygen and glucose decreased closer to the infarct region (P < .001 for all). Infarct-related oxygen utilization and extraction of oxygen and glucose were closely related to outcome (P < .01 for all). PTF improved significantly in the infarct-related regions over time in proportion to early oxygen extraction and utilization. Conclusions. This pilot study indicates that PET might be useful in the evaluation of treatment efficacy and that restoration of oxidative metabolism is more closely related to myocardial damage recovery than perfusion in the early phase after MI.