Abstract 15687: Myocardial Coronary Flow Reserve Predicts Adverse Clinical Outcomes Independently of Luminal Angiographic Score
Background: Coronary vascular dysfunction, even in the absence of overt obstructive coronary artery disease (CAD), identifies patients at risk for cardiac death. We tested the hypothesis that presence of abnormal coronary flow reserve (CFR) is associated with luminal angiographic severity, and that abnormal CFR and severe angiographic stenoses are associated with adverse clinical outcomes.
Methods: We included 194 consecutive pts without history of prior CAD or ejection fraction <40% who underwent coronary angiography within 90 days after stress testing with myocardial perfusion positron emission tomography (PET). Myocardial blood flow (MBF, mL/min/g) was quantified at rest and at peak vasodilator stress. CFR was estimated from the ratio of stress/rest MBF. Extent of CAD on luminal angiography was quantified using the Modified Duke Coronary Artery Disease Index (MDCADI). Pts were followed for a median of 2.13 years [IQR 0.32-3.4] for the occurrence of major adverse clinical events (MACE) including death or heart failure hospitalization.
Results: Abnormal CFR is significantly associated with severe luminal angiographic score (Pearson r=-0.30, p<0.0001). Compared with pts without MACE (n=141), those with MACE (n=53, including 36 deaths) had lower peak MBF (1.47 [1.06-1.93] vs. 1.81 [1.21-2.17] mL/min/g, p=0.03) and CFR (1.50 (se 0.07) vs. 1.83 (se 0.06), p<0.01), and scored higher on MDCADI (44.2 [23-56] vs. 23.0 [0-56], p=0.03). In unadjusted analysis, the subgroup of pts with abnormal CFR (<2) and high-risk angiographic stenoses (MDCADI ≥37) showed highest cumulative incidence of MACE (p<0.01). In a Cox proportional hazards model adjusting for clinical pre-test probability, left ventricular ischemia, ejection fraction, and early revascularization, CFR and MDCADI remained significantly associated with MACE (adjusted HR 0.50 [95%CI 0.29-0.87] and HR 1.02 [1.01-1.03], respectively).
Conclusions: CFR is mildly associated with luminal angiographic stenoses, but both CFR and angiographic severity are independent predictors of adverse clinical outcomes. Diffuse atherosclerosis and coronary microvascular dysfunction may play a role in the pathophysiologic abnormalities leading to increased risk of death or heart failure.
- © 2013 by American Heart Association, Inc.