Association Between Coronary Vascular Dysfunction and Cardiac Mortality in Patients with and without Diabetes Mellitus
Background—Diabetes increases the risk of adverse cardiac outcomes and is considered a coronary artery disease (CAD) equivalent. We examined whether coronary vascular dysfunction, an early manifestation of CAD, accounts for increased risk among patients with diabetes compared to non-diabetics.
Methods and Results—2783 consecutive patients (1172 diabetics and 1611 non-diabetics) underwent quantification of coronary flow reserve (CFR=stress divided by rest myocardial blood flow) by PET and were followed for a median of 1.4 years (Q1-Q3: 0.7-3.2). The primary endpoint was cardiac death. Impaired CFR (below the median) was associated with an adjusted 3.2 and 4.9-fold increase in the rate of cardiac death for diabetics and non-diabetics, respectively (p=0.0004). Addition of CFR to clinical and imaging risk models improved risk discrimination both diabetics and non-diabetics (c-index: 0.77 to 0.79, p=0.04, and 0.82 to 0.85, p=0.03, respectively). Diabetic patients without known CAD with impaired CFR experienced a rate of cardiac death comparable to that for non-diabetic patients with known CAD (2.8 vs 2.0%/year, P=0.33). Conversely, diabetics without known CAD and preserved CFR had very low annualized cardiac mortality, which was similar to patients without known CAD or diabetes and normal stress perfusion and systolic function (0.3 vs. 0.5%/year, P=0.65).
Conclusions—Coronary vasodilator dysfunction is a powerful, independent correlate of cardiac mortality among both diabetics and non-diabetics and provides meaningful incremental risk stratification. Among diabetic patients without CAD, those with impaired CFR have event rates comparable to patients with prior CAD while those with preserved CFR have event rates comparable to non-diabetics.
- Received May 24, 2012.
- Accepted August 1, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited