A new method to quantify coronary calcification by intravascular ultrasound - the different patterns of calcification of acute myocardial infarction, unstable angina pectoris and stable angina pectoris
Wang, X.; Lu, C.; Chen, X.; Zhao, X.; Xia, D.
Journal of Invasive Cardiology 20(11): 587-590
ISSN/ISBN: 1557-2501 PMID: 18987398 Accession: 051180809
Intravascular ultrasound (IVUS) enables the identification of calcification with more details and quantification of calcification, but there is not a proper method to quantify the calcification with IVUS. Previous IVUS studies used arc or length of calcium, respectively, to quantify calcification, but calcium is determined by a combination of arc and length. We devised a new method to quantify calcium as arc area (AA) in the present study, and AA is two-dimensional and irrelevant to vessel size. We selected 201 patients with stable angina pectoris (SAP), unstable angina pectoris (UAP), or acute myocardial infarction (AMI) who underwent IVUS imaging of a de novo native atherosclerotic lesion considered to be the culprit lesion before percutaneous coronary intervention between December 2001 and December 2007. The culprit lesion site for analysis was the 10 mm-long segment including the smallest lumen cross-sectional area. The arc of each calcium deposit in each image was measured with a protractor centered on the lumen and the length of each calcium deposit was calculated with the number of images containing the calcium deposit minus 1, then multiplying 0.5 mm (the images were 0.5 mm apart). Finally, the AA was calculated by arc (degree) multiplying length (mm). The average number of calcium deposits in the culprit lesions of patients with acute myocardial infarction (AMI) was significantly larger than patients with SAP or UAP, and the number of calcium deposits of patients with SAP or UAP was almost the same (mean +/- SD, AMI 2.21 +/- 1.98, SAP 1.15 +/- 1.01, UAP 1.20 +/- 1.15, AMI versus SAP or UAP; p < 0.0005). The average AA per calcium deposit was significantly different in culprit lesions of patients with SAP and UAP or AMI, the calcium deposits were bigger in SAP than in UAP or AMI, and there were no differences between UAP and AMI (mean +/- SD, SAP 788.6 +/- 767.0 degree x mm, UAP 136.6 +/- 189.3 degree x mm, AMI 148.4 +/- 217.1 degree x mm, SAP versus UAP or AMI; p < 0.0005). The total AA of culprit lesions per patient was greatest in patients with SAP, less in patients with AMI, and least in patients with UAP (mean +/- SD, SAP 903.3 +/- 1018.8 degree x mm, AMI 301.1 +/- 401.5 degree x mm, UAP 163.9 +/- 279.6 degree x mm, SAP versus UAP or AMI; p < 0.0005, AMI versus UAP; p < 0.01). The culprit lesions of patients with SAP, AMI, or UAP have greatest, less, or least calcification burden, respectively. The culprit lesions of patients with SAP have larger and fewer calcium deposits, patients with AMI have smaller and more numerous calcium deposits, and patients with UAP have smaller and fewer calcium deposits.