Comparison of Coronary Calcium in Stable Angina Pectoris and in First Acute Myocardial Infarction Utilizing Double Helical Computerized Tomography

Abstract

Although coronary calcium is invariably associated with atherosclerosis, its role in the pathogenesis of acute and chronic coronary syndromes remains unclear. Utilizing double helical computerized tomography we evaluated the coronary calcium patterns in 149 patients: 47 with chronic stable angina (SAP) compared with 102 patients surviving a first acute myocardial infarction (AMI). Prevalence of coronary calcium was 81% among the AMI patients and 100% in the stable angina patients. The 547 calcific lesions identified in the AMI patients and the 1,242 lesions in the stable angina patients were categorized into 3 groups according to their extent: mild, intermediate, and extensive. The age-adjusted percentages of the highest level of calcification among AMI versus stable angina patients were: mild 18% vs 3%, intermediate 49% vs 18%, and extensive lesions 33% vs 79%, respectively (p <0.01). In the AMI group, 73 culprit arteries were identified: 16 (22%) had no calcium detected, whereas 30 (41%) had mild lesions, 20 (27%) had intermediate forms, and only 7 (10%) had extensive lesions. The age-adjusted mean of the natural logarithm transformation of total calcium scores +1 was significantly lower in patients with AMI than in those with SAP (4.1 [95% confidence interval 3.7 to 4.4) vs 5.3 [95% confidence interval 4.8 to 5.8]). Thus, double helical computerized tomography demonstrates that extensive calcium characterizes the coronary arteries of patients with chronic stable angina, whereas a first AMI most often occurs in mildly calcified or noncalcified culprit arteries.