Prevalence and clinical implications of newly revealed, asymptomatic abnormal ankle-brachial index in patients with significant coronary artery disease

Objectives: This study sought to evaluate the association between newly revealed abnormal ankle-brachial index (ABI) and clinical outcomes in patients with significant coronary artery stenosis.

Background: Little is known about the prevalence and clinical implications of ABI in patients with no claudication or previous history of peripheral artery disease who undergo diagnostic coronary angiography.

Methods: Between January 1, 2006, and December 31, 2009, ABI was evaluated in 2,543 consecutive patients with no clinical history of claudication or peripheral artery disease who underwent diagnostic coronary angiography. Abnormal ABI was defined as ≤0.9 or ≥1.4. The primary endpoint was the composite of death, myocardial infarction, and stroke over 3 years.

Results: Of the 2,543 patients, 390 (15.3%) had abnormal ABI. Of the 2,424 patients with at least 1 significant stenosis (≥50%) in a major epicardial coronary artery, 385 (15.9%) had abnormal ABI, including 348 (14.4%) with ABI ≤0.9 and 37 (1.5%) with ABI ≥1.4. During a median follow-up of 986 days, the 3-year major adverse event rate was significantly higher in patients with abnormal than normal ABI (15.7% vs. 3.3%, p < 0.001). After multivariate analysis, abnormal ABI was identified as a predictor of primary endpoint (hazard ratio [HR]: 1.87; 95% confidence interval [CI]: 1.23 to 2.84; p = 0.004). After adjustment by propensity-score matching, abnormal ABI could predict adverse clinical events in patients with established coronary artery disease (HR: 2.40; 95% CI: 1.41 to 4.10; p = 0.001).

Conclusions: The prevalence of newly revealed abnormal, asymptomatic ABI among patients who have significant CAD on coronary angiography was 15.9%. The presence of abnormal ABI was associated with a higher incidence of adverse clinical outcomes over 3 years.