The prognostic value of global myocardial flow reserve (MFR) is well established. However, only limited data exist on the value of regional myocardial reduction myocardial flow reserve.
The goal of this study was to determine the impact of regional variations of MFR in patients without known coronary artery disease.
We retrospectively included 146 consecutive patients without known coronary artery disease (CAD) who underwent clinically indicated 13N-ammonia myocardial perfusion positron emission tomography (PET) at our institution. Global and regional MFR, based on a 17-segment model were calculated. Patients were classified into three groups. Group 1: Patients with preserved global and regional MFR. Group 2: Patients with preserved global but reduced regional MFR (i.e. = 3 adjacent segments with MFR < 2.12 ml/min/g). Group 3: Patients with reduced global MFR (i.e. < 2 ml/min/g). Follow-up was obtained regarding a composite endpoint including all-cause death, nonfatal myocardial infarction, and late revascularization (i.e. = 60 days after the PET scan). We performed Kaplan-Meier and Cox regression analysis.
During a median follow-up of 47±36 months, a total of 24 events (15 deaths, 2 nonfatal myocardial infarctions, 7 late revascularizations) occurred. Annual event rate was 1.43% in group 1, 4.76% in group 2, and 3.11% in group 3. Kaplan-Meier analysis showed a significant difference between these groups (log Rank p=0.046). While group 1 differed significantly from group 2 (log Rank p=0.013) and group 3 (log Rank p=0.013), there was no difference between Group 2 and 3. Multivariate Cox regression revealed a reduced regional MFR as an independent predictor for future cardiac events (p=0.011).
In patients without known CAD global and regional MFR impact prognosis. However, in the present study, only regional MFR was found to be an independent predictor of adverse cardiovascular outcome.