Abstract 14579: Peak Myocardial Blood Flow versus Noninvasive Coronary Flow Reserve for Prediction of Future Events

Abstract

Background: Impaired coronary flow reserve (CFR) is an early manifestation of coronary artery disease (CAD), even in vessels free of angiographic stenosis. The aim of this analysis is to determine the differential role peak myocardial blood flow (MBF) or noninvasive CFR in predicting future events. Methods: We included 3,003 consecutive patients with known or suspected CAD (mean age 61±11years, 42% females) who underwent rubidium-82 rest/stress positron emission tomography (PET) for clinical indications. Rest and peak MBF were calculated with factor analysis and a 2-compartment kinetic model and were used to calculate CFR. Patients were followed up for a median duration of 1.4 years (interquartile range, 0.5-1.8 years) for the incidence of cardiac death or myocardial infarction. (CDMI). Multiple Cox regression models were used to determine the prognostic value of peak MBF and CFR and the incremental value of peak MBF over CFR. Results: The included cohort has prevalence of CAD risk factors: Diabetes (60%), hypertension (87%) and dyslipidemia (85%). A total of 40% patients had evidence of perfusion defects (Sum stress score>3). After a median follow up duration of 1.4 years, 140 patients (4.7%) experienced CD/MI. In multivariate Cox regression adjusted for Duke clinical risk score, resting ejection fraction and SSS, both CFR (Hazard Ratio 0.70, 95% CI 0.54 -0.89, p=0.005) and peak MBF (Hazard Ratio 0.71, 95% CI 0.57 -0.89, p=0.003) were independent predictors of CDMI. (Adding peak MBF added incremental prognostic value over CFR. (Area under the curve increased from 0.776 to 0.793, p=0.021). Conclusion: Noninvasively measured MBF and CFR are independent predictors of CDMI in patients with known or suspected CAD. Peak MBF adds incremental prognostic value over noninvasive CFR.