Objectives: The Ankle-Brachial index (ABI) is a highly effective tool for diagnosing peripheral artery disease. Peripheral arterial disease (PAD) is frequently under-diagnosed condition in the clinical setup which leads to a lack of opportunity in detection of subjects at a high risk for cardiovascular (CV) death. But use of the Ankle-Brachial index (ABI) till date has not been validated for the diagnosis of coronary artery disease.

Aim of this Study: To evaluate the ability of the ankle-brachial index in prediction of coronary artery disease in patients undergoing coronary angiography.

Methods: Patients with clinical suspicion of coronary artery disease and indication for coronary angiography were prospectively evaluated. Significant coronary artery disease was defined as the presence of stenosis >70% of at least one of the major epicardial coronary artery or any of their major branches. A ROC curve was developed to define the ankle-brachial index cutoff that best predicts coronary artery disease.

Results: A total of 51 patients were evaluated: mean age was 56 ± 12  years and 55% of them were males. Ninteen (37.2%) patients had significant coronary disease. Ankle-brachial index measurement in these patients was significantly lower than in those without coronary artery disease (0.78 ± 0.14 vs. 0.86 ± 0.87; p <0 .01). Ankle-brachial index <0.87 showed a sensitivity of 31%, specificity of 96.4%, positive predictive value of 76.9% and negative predictive value of 71.6%. The area under the receiver operating characteristic (ROC) curve was 0.73 (95% confidence interval of 0.67-0.79).

Conclusions: ABI values ≤ 0.87 showed high specificity to predict significant coronary artery disease.

Keywords: Atherosclerosis. Cardiovascular diseases. Ankle brachial index. Risk factors. Coronary angiography, receiver operating characteristic (ROC) curve.

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Dr Rajiv Girdhar

Assistant Professor in Cardiology Department in Rajarajeswari Medical College and Hospital, Bangalore