Left ventricle ejection fraction correlates with infarct size as well as myocardial perfusion reserve

Objectives Left ventricular function after myocardial infarction is considered to be determined by the size of the infarction and residual function of the spared myocardium. Myocardial perfusion reserve assessed by 13N-ammonia PET has been shown to be a strong predictor in patients with ischemic heart failure. Unknown is the value of MPR in the spared myocardium in relation with infarct size and LVEF. In the present study, the interrelationship between MPR, LVEF and infarct size was investigated.

Methods In this study, 118 patients with a prior history of myocardial infarction were included. All underwent rest - dypiridamole stress 13N-ammonia and gated FDG PET for evaluation of myocardial perfusion reserve and viability. FDG polar maps were used to determine the size of the infarction. The LVEF was obtained by gated FDG PET or another available method within 3 months of the PET scan. The segmental MPR was obtained by dividing stress and rest myocardial perfusion in the spared myocardium.

Results Mean age of the subjects was 69 ± 12 years (92 men;78%), global MPR was 1.65 ± 0.51. Mean LVEF was 36 ± 9.8%, mean infarct size 23.6 ± 14.6%. Fifty patients had dyslipidemia, 41 hypertension, 13 diabetes, 45 were smokers, and 35 a positive family history for cardiovascular disease. Linear regression model was applied for the analysis considering the LVEF as an independent variable. All risk factors, infarct size and MPR were entered as variable. The infarct size (P <0.001) and MPR (P = 0.008) reached statistical significance. Of all risk factors only diabetes mellitus (P = 0.030) showed a significant correlation with LVEF.

Conclusions 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