Coronary calcium and coronary artery disease: an Indian perspective

Coronary artery calcification is a part of the development of atherosclerosis. It occurs exclusively in atherosclerotic arteries and can be used as a noninvasive marker of coronary atherosclerosis. As there is no large-scale study on coronary calcium score reported in the Indian population till date, this study was undertaken for calculating the score in Indians at intermediate-to-high risk of coronary artery disease, and to correlate it with angiographically proven coronary artery disease.

A total of 388 consecutive patients who underwent coronary calcium scoring and coronary angiography were included in the study. Calcium scoring was performed based on a modification of the Agatston Score using a high-speed computed tomography scanner (GE CT/i scanner). Coronary calcium scores were correlated with the presence or absence of significant coronary artery disease (defined as > or = 70% stenosis of at least one major epicardial coronary artery) on angiography. Out of 388 patients who underwent coronary angiography, 298 were found to have significant coronary artery disease. Mean coronary calcium score was significantly higher in patients with angiographically proven coronary artery disease (226.7+/-65.2) as compared to those who had normal angiograms (20.29+/-56.7; p value<0.0001). All the 72 patients who had a score > 400 had an abnormal angiogram (sensitivity 23.1%, specificity 100%, positive predictive value 100%, and negative predictive value 24.1%). On the other hand, among the patients who had a score > 0, 298 were found to have abnormal angiograms, while 16 had normal angiograms (sensitivity 95.5%, specificity 78.9%, positive predictive value 94.9%, and negative predictive value 81.1%).

Detection of coronary calcium score by a helical computed tomography scanner is a useful tool for predicting the presence of significant coronary artery disease in intermediate-to-high risk patients. An absolute score of 0 has a high negative predictive value for the presence of coronary artery disease, and may obviate the need to perform coronary angiogram in intermediate-risk patients. On the other extreme, score > 400 is highly predictive of the presence of coronary artery disease, and virtually confirms the presence of significant coronary artery disease in intermediate-to-high risk patients.