Abnormal ankle brachial index and the presence of significant coronary artery disease.

OBJECTIVE To determine the association between an abnormal ankle brachial index (ABI) and the presence of significant coronary artery disease (CAD) on coronary angiography. STUDY DESIGN Cross-sectional, observational study. PLACE AND DURATION OF STUDY The study was carried out at Sheikh Zayed Hospital, Lahore, from July to October 2007. METHODOLOGY A series of 41 patients undergoing coronary angiography in Sheikh Zayed Hospital were selected and their ABI were calculated before the diagnostic coronary angiography. ABI calculations and coronary angiography reporting were done by separate individuals and data was analysed using SPSS 12.0. All patients undergoing diagnostic coronary angiography were included in the study except for those having peripheral arterial disease documented by lower extremity revascularization, lower extremity ulceration and lower extremity amputation. Proportion were compared using chi-square test with significance at p < 0.05. RESULTS Out of the 41 patients 31 male (76%) and 10 female (24%), 3 patients (7.31%) had ABI < 0.9 and all 3 had triple vessel disease. Ten patients (24%) had ABI 0.91-0.99 and 2 (20%) of them had single vessel disease. Two (20%) had double vessel disease and 6 (60%) had triple vessel disease. Twenty four patients (58%) had ABI of 1.00-1.28 and 8 (33%) of these had single vessel disease, 3 (12%) had double vessel disease and 13 (55%) had triple vessel disease, while 4 patients had normal coronaries. A total of 22 patients were found to have triple vessel disease and only 3 (13.6%) of these 22 patients had an ABI < 0.9 which is statistically not significant (p=0.07). CONCLUSION This study was not able to establish a direct association between ABI and significant CAD as only 3 patients out of 22 with triple vessel disease had an ABI < 0.9. However, an approximately log linear relationship was noted between ABI and CAD risk which means that not only the average CAD risk increased exponentially at values < 1.0 but also that the CAD risk continued to decline as ABI values increased above 1.0.