Combination Of Ankle-brachial Index And Coronary Artery Calcium Score As A Predictor For 3-vessel Coronary Artery Disease

Background and ObjectiveAlong with the aging of populations, coronary artery disease (CAD) has become one of the main murderers who harm the health of human being. Especially, the patients with 3-vessel CAD (including left main branch pathological lesion) has not only higher incidence of cardiovascular events, but also higher risk of death. It is important to screen out patients with 3-vessel CAD to improve their prognosis. In recent years, it became one of the hottest spots in the medical research fields of how to predict the stenotic extent of the lesion morphology of coronary artery by non-invasive methods. Ankle-brachial index (ABI) has been confirmed to be simple, accurate and non-invasive to diagnose peripheral artery disease. And now, it is also found to be consistent with the stenotic extent of lesion morphology of coronary artery. What's more, coronary artery calcification is almost all on the basis of coronary atherosclerosis, and the degree of calcification is directly related to the severity of atherosclerosis. Through the integral way of coronary artery calcium score (CACS), the burden of coronary artery calcification and even the extent of atherosclerosis can be known.In this study, we detected ABI and CACS of the elderly and compared those results with the results of coronary angiography (CAG) which was considered as the gold standard of predicting the stenotic extent of the lesion morphology of coronary artery. The purposes of this study are as follows: 1 To get the cut-off points of ABI and CACS to predict 3-vesssel CAD and calculate out the sensitivity, specificity and accuracy of ABI and CACS to predict 3-vessel CAD; 2 To investigate whether the predicting value can be improved when both of ABI and CACS is combined. All those are to find a non-invasive and inexpensive method with good sensitivity and specificity to predict 3-vessel CAD, which would be a useful supplement to CAG and CTA. Subjects and methods1. Subjects and group This study enrolled total 96 elderly patients (>60-year-old), who underwent ABI, CACS and CAG measurements and agreed to join this study. All those subjects (58 male and 38 female) were from the department of cardiology, whose age ranged from 60 to 92 years old (the mean age was 69.0±7.9 years old). According to the results of CAG, the subjects were divided into two groups: the subjects whose all 3 vessels including left anterior descending branch, left circumflex branch and right coronary artery or left main branch were there significant stenosis exceeding 50% diameter reduction was classified as group of 3-vessel , and the remains were classified as control group.2. Methods Clinical data collection were as follows: gender, age, body mass index, diabetes, hypertension, plasma lipid disorders, history of smoking, family history of cardiovascular disease, fasting plasma glucose level, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), measurements of ABI, CACS and coronary angiography (CAG). The baseline information was compared to investigate whether there was significant difference in the two groups. The results of CAG were determined as the gold standard of predicting 3-vessel CAD, the best cut-points of ABI and CACS to predict 3-vessel CAD were analyzed through ROC curve, and the contribution of them to predict 3-vessel CAD was analyzed through Logistic regression,. Then the diagnostic value of ABI, CACS and the parallel test of ABI and CACS were analyzed to investigate whether combining the two methods can improve their diagnosis value.Results1 The baseline information concluded age, sex, history of diabetes, hypertension, plasma lipid disorders history, history of smoking, family history of cardiovascular disease, body mass index, plasma lipid level etc. The baseline information between the two groups was found no significant difference;2 As compared, ABI <0.9 and CACS> 400 were the best cut-point values with maxim Youden index which were determined by ROC curve;3 ABI<0.9 and CACS>400 were independent predictors for 3-vessel CAD;4 The sensitivity and specificity for ABI<0.9 to predict 3-vessel lesions were 58% and 87%, the sensitivity and specificity for CACS>400 were 64% and 86%, and that for parallel test of combining ABI and CACS were 85% and 83% . The sensitivity significantly increased (P<0.05) and the specificity slightly dropped, but the difference was not statistically significant.Conclusions1. As compared, ABI <0.9 and CACS> 400 were the best cut-point value and independent predictors for 3-vessel CAD;2. The cut-off point of ABI <0.9 and CACS> 400 to predict 3-vessel CAD had high specificity but low sensitivity;3. The parallel test of combining ABI <0.9 and CACS> 400 greatly increased the sensitivity for predicting 3-vessel CAD and did not significantly decreased specificity. Combined use of ABI and CACS would have more practical value.