Impact of Low Ankle-Brachial Index on the Risk of Recurrent Vascular Events

Abstract

Background and Purpose- Low ankle-brachial index (ABI) identifies a stroke subgroup with high risk of recurrent stroke, cardiovascular events, and death. However, limited data exist on the relationship between low ABI and stroke in low and middle-income countries. Therefore, we evaluated the prevalence of ABI ≤0.90 (which is diagnostic of peripheral artery disease) in nonembolic stroke patients or transient ischemic attack and assessed the correlation of low ABI with stroke risk, factors, and recurrent vascular events and death. Methods- Patients ≥45 years with acute transient ischemic attack or minor ischemic strokes were recruited consecutively from over 17 low-income and middle-income countries (Latin America [1543 patients], Middle East [1041 patients], North Africa [834 patients], and South Africa [217 patients]). The ABI measurement was performed at a single visit. Stroke recurrence and risk of new vascular events were assessed after 24 months of follow-up. Results- Among 3487 enrolled patients, abnormal ABI (<0.9) was present in 22.3 %. Patients with an ABI of ≤0.9 were more likely ( P<0.05) to be male, older, and have a history of peripheral artery disease, hypertension, and diabetes mellitus. During 2-year follow-up, the rate of major cardiovascular event was higher in patients with ABI <0.9 than those with ABI ≥0.9 (Kaplan-Meier estimates, 22.5%; 95% CI, 19.6-25.8 versus 13.7%; 21.4-15.1; P<0.001), and when ABI was categorized into 4 groups (≤0.6; 95% CI, 0.6-0.9; 0.9-1; 1-1.4), the rate of major cardiovascular event was higher in those with ABI ≤0.6 than the other groups (Kaplan-Meier estimates, 32.6%; 95% CI, 21.0-48.3 for ABI≤0.6 versus 21.7%; 95% CI, 18.8-25.0 for ABI 0.6-0.9 versus 14.3%; 95% CI, 12.4-16.6 for ABI 0.9-1 versus 13.3%; 95% CI, 11.6-15.2 for ABI 1-1.4; P<0.001). Conclusions- Among patients with nonembolic ischemic stroke or transient ischemic attack, those with low ABI had a higher rate of vascular events and death in this population. Screening for ABI in stroke patients may help identify patients at high risk of future events.