Ankle-Brachial Index: A Simple and Inexpensive Screening Test for Coronary Artery Disease (ABI goes beyond the foot)

Background: Coronary artery disease (CAD) is the leading cause of death in the world. In this study we assessed ankle-brachial index (ABI) as a screening tool for CAD. Method: Between 2019 and 2020, large cross-sectional population-based study of 4207 new patients referred to cardiovascular Clinic was enrolled. The patients underwent selective coronary angiography via radial artery approach. ABI was calculated for all patients. We compared ABI with the results of coronary angiography to determine the specificity and sensitivity of ABI as a screening tool for CAD. Results: Abnormal ABI was significantly more frequent in patients with proven severe CAD (893, 54.8%) than in patients with proven mild CAD (33, 4.7%) or no CAD (94, 5.3%). The specificity of ABI was 95.3%, and its sensitivity was 54.8%. ABI was associated with risk factors such as smoking, male gender, hypertension, diabetes mellitus and dyslipidemia. Conclusion: ABI can be used as a screening test to rule out CAD with 95.3% specificity. We need to consider risk factors other than ABI to increase screening sensitivity. A multidimensional scoring system should consider risk factors and other noninvasive tests in addition to ABI to develop and ideal screening system for CA. (Clinical trial registration number NCT04667832)