13N-AMMONIA PET-DERIVED VENTRICULAR SYNCHRONY CORRELATES WITH MYOCARDIAL PERFUSION RESERVE BETTER THAN LEFT VENTRICULAR EJECTION FRACTION: A STUDY IN INFARCTED PATIENTS

Background: PET myocardial perfusion allows myocardial perfusion reserve (MPR) quantification as well as left ventricular ejection fraction (LVEF) and synchrony estimation through phase analysis. There is a relationship between MPR and LVEF and both have proven prognostic value in coronary artery disease (CAD). A relation between angiographic CAD extent and post-stress synchrony has been proposed with SPECT. We used 13N-ammonia PET to evaluate the relationship between MPR and ventricular synchrony in patients with a previous infarction and secondarily, to compare it to the relation MPR-LVEF. Methods: We studied 63 patients (64.4±11.1years) with a previous myocardial infarction with a rest/adenosine-stress 13N-ammoniaPET. Demographics and cardiovascular history were retrieved. MPR was calculated dividing the stress by the rest blood flow. Synchrony was evaluated through Entropy, systolic function through LVEF and the area of previous infarction through the resting total perfusion defect (TPD). Two multiple regressions were done: the first used Entropy as dependent variable and MPR, TPD and clinical variables as predictors; in the second LVEF replaced the dependent variable. The standardized regression coefficients were compared. Results: There were 49 males and 14 females, 39% with diabetes, 54% with hypertension, 54% with dyslipidemia, 42% of smokers and 44% with chest pain. Mean MPR=2.14±0.79, mean TPD=15.8%±11.2, mean LVEF=49%±17 and mean Entropy=53.4%±11.8. The first regression showed a significant independent relation between MPR and Entropy (β=-.384, p=0.006). This relation was greater than the one between MPR and LVEF (β=.292, p=0.013) in the second regression. In both, TPD (p=0.021, p=0.001) and gender (p=0.041, p=0.001) showed a significant correlation with the dependent variables. Conclusions: In patients with a previous myocardial infarction, PET-measured MPR significantly correlates to ventricular synchrony independently from the area of infarction. This correlation is stronger than the one between MPR and LVEF. Our results warrant further research into the added prognostic value of PET-measured ventricular synchrony and entropy in the setting of CAD.