Abstract 15719: Prognostic Interplay Between Myocardial Flow Reserve and Left Ventricular Ejection Fraction

Introduction: Myocardial flow reserve (MFR), measured using positron emission tomography (PET), has been shown to add incremental prognostic value in multiple patient populations. Whether this association is modified by left ventricular ejection fraction (LVEF) is not well studied. The aim of this analysis is to determine whether there is a prognostic interplay between myocardial flow reserve and LVEF.

Methods: The study population included patients who had clinically indicated PET myocardial perfusion imaging and were prospectively followed for incident events. MFR was calculated as the ratio of stress to rest myocardial blood flow (MBF) (ml/min/g). Rest LVEF was calculated from end systolic and end diastolic LV volumes on gated images. Cox proportional hazards were used to study the association between MFR (<2 vs ≥2) and incident cardiovascular events stratified by LVEF (<50% vs ≥50%).

Results: The study population included 5,523 patients (mean±SD age 67±12 years, 53% male), 16% of LVEF<50% and 47% MFR <2. Rest MBF was similar among patients with normal or reduced LVEF while stress MFR was lower with lower EF. In adjusted analysis, patients with impaired MFR had a higher incident event rate regardless of LVEF (Figure 1). Patients with MFR<2 had a higher risk of incident outcomes in both LVEF ≥50% (HR=2.58, 95% CI:1.93 - 3.46, p<0.001) and LVEF <50% (HR=2.76, 95% CI: 1.62 - 4.70, p<0.001); p-value for interaction= 0.045.

Conclusions: Impaired MFR is associated with a higher risk of cardiovascular outcomes and death in patients with high or low LVEF.