Prognostic Value of Abnormal Ankle-Brachial Index in Patients With Coronary Artery Disease: A Meta-Analysis

The prognostic value of the ankle-brachial index (ABI) in patients with coronary artery disease (CAD) remains undefined. This meta-analysis sought to investigate the association of abnormal ABI and adverse outcomes in patients with CAD. PubMed, Embase, China National Knowledge Infrastructure, VIP, and Wanfang databases were comprehensively searched for studies published from inception to September 10, 2019. All observational studies investigating the association of abnormal baseline ABI and risk of major adverse cardiovascular events (MACE) or all-cause mortality were selected. Normal ABI is usually defined as between 0.9 and 1.4. The prognostic values were summarized by pooling risk ratio (RR) with 95% confidence intervals (CIs) for abnormal versus normal ABI category. Nine (9384 patients with CAD) studies were included. Abnormal ABI was independently associated with MACE (RR: 2.46; 95% CI: 2.02-2.99) and all-cause mortality (RR: 1.74; 95% CI: 1.32-2.30). Subgroup analysis showed that the pooled RR for MACE was 2.34 (95% CI: 1.73-3.16) for an abnormal low ABI. Abnormal ABI predicts MACE and all-cause mortality in patients with CAD, even after adjusting conventional confounding factors. However, the prognostic value of abnormal ABI is mainly dominated by a low ABI rather than a high ABI.