Myocardial perfusion reserve in spared myocardium: correlation with infarct size and left ventricular ejection fraction

Abstract

Left ventricular ejection fraction (LVEF) after myocardial infarction is considered to be determined by the size of the infarction and residual function of the spared myocardium. Myocardial perfusion reserve (MPR) has been shown to be a strong prognostic factor in patients with ischaemic heart failure, even stronger than LVEF. In the present study, the interrelationship between MPR, LVEF and infarct size was investigated. In total, 102 patients with a prior history of myocardial infarction were included. All underwent rest and stress (13)N-ammonia and gated (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) for evaluation of myocardial ischaemia and viability. FDG polar maps were used to determine the size of the infarction. The LVEF was obtained by gated (18)F-FDG PET or another available method within 3 months of the PET scan. MPR was obtained per segment in the spared myocardium. The mean age of the subjects was 68 ± 12 years. Global MPR was 1.63 ± 0.51. The mean LVEF was 36 ± 10 % and mean infarct size 23.72 ± 14.8 %. A linear regression model was applied for the analysis considering the LVEF as a dependent variable. All risk factors, mean stress flow, infarct size and MPR were entered as variables. The infarct size (p < 0.001) and MPR (p = 0.04) reached statistical significance. In a multivariate model MPR had a stronger correlation with LVEF than infarct size. In patients with a prior history of myocardial infarction, LVEF is not just related to infarct size but also to MPR in the spared myocardium.