Abstract 1776: Peripheral Arterial Disease Determined by Screening Ankle Brachial Index Testing Predicts High Risk Findings On Stress Myocardial Perfusion SPECT Imaging
Background: Peripheral arterial disease (PAD) as determined by ankle brachial index (ABI) testing is a potent marker of adverse cardiovascular prognosis. Stress myocardial perfusion SPECT (MPS) testing allows diagnosis of coronary artery disease (CAD) and stratification of cardiovascular risk. The stress MPS findings in patients (pts) with occult PAD are unknown. Accordingly, our goal was to determine the prevalence high risk (HR) MPS findings in pts with occult PAD diagnosed by screening ABI who are referred for MPS testing.
Methods: As part of a prospective data collection, 679 male pts referred for MPS were screened for PAD with ABI evaluation. Pts with non-diagnostic ABIs (>1.3) or prior known PAD were excluded. PAD was defined as an ABI ≤ 0.9. PAD severity (mild [ABI 0.8 – 0.9], moderate [ABI 0.4 – 0.8], severe [<0.4]) and symptoms of PAD were also noted. CAD was defined as mild (summed stress score (SSS) ≥ 4) or severe (SSS>8), and the composite of any HR finding (SSS>8, left ventricular ejection fraction [LVEF] < 40%, or TID) was recorded.
Results: PAD was present in 28%. Of pts found to have PAD, 65% reported no lower extremity symptoms. Compared to no PAD, pts with PAD were found to have significantly more mild or greater CAD (51% vs. 36%, p<0.01), severe CAD (35% vs. 19%, p<0.01), LV dysfunction [LVEF < 40%] (14% vs 7%, p < 0.01), and composite HR MPS findings (40% vs. 22%, p<0.01). On multivariate logistic regression analysis considering age, HTN, diabetes, tobacco use, hypercholesterolemia, and prior coronary artery disease, PAD was found to be an independent predictor of mild or greater CAD (OR 1.6, 95% CI 1.1–2.4, p<0.01), severe CAD (OR 1.9 95% CI 1.3–3.0, p<0.01), and any HR MPS finding (OR 2.0 95% CI 1.3–3.0, p<0.01).
Conclusions: Among men referred for stress testing, occult PAD is common, and is an independent predictor of significant CAD and HR findings on MPS testing. Further study is needed to determine if PAD in pts without an indication for stress testing may benefit from screening MPS.