[BACKGROUND] Calcification is an important phenomenon of atherosclerosis. Histopathological and intravascular ultrasound studies suggest that the characteristics of calcification might be associated with the pathogenesis of the vulnerable plaque. Optical coherence tomography (OCT) is a high-resolution imaging modality and allows us to analyse the plaque morphology in detail. In this study, we assessed the characteristics of calcification by OCT at the sites of culprit lesions in acute myocardial infarction (AMI), unstable angina pectoris (UAP), and stable angina pectoris (SAP).
[METHOD and RESULTS] We evaluated the characteristics of calcification in the 20-mm-long culprit lesion segment per patient by OCT in 56 patients (AMI : n=21, UAP : n=14, SAP : n=21). In each patient, the number of calcium deposits, the arc, the distance from the luminal surface to each calcification were measured. Each calcium deposit was categorized into one of two groups by the arc :
spotty calcification : a small calcium deposit with an arc of less than 90 degrees ;
large calcification : a calcific lesion with an arc of more than 90 degrees.
The average number of spotty calcification per patient in AMI and UAP was significantly greater than that in SAP (AMI 1.7+/−1.3, UAP 1.9+/−1.7, and SAP 0.6+/−0.8, p=0.012; AMI vs SAP, p=0.046, UAP vs SAP, p=0.030). The average number of large calcification per patient in AMI was significantly lower than that in SAP (AMI0.2+/−0.4, UAP 0.42+/−0.7, and SAP0.9+/−0.7; AMI vs SAP, p=0.005). Consequently, the percent of spotty calcification in each culprit lesion was higher in AMI and UAP than in SAP (AMI 87.5%, UAP 81.3%, and SAP40.1%, p<0.01). The distance between the luminal surface and the inner edge of each spotty calcification was significantly shorter in AMI and UAP than in SAP (AMI 0.18+/−0.11mm, UAP 0.15+/−0.1mm, SAP 0.30+/−0.13mm, p<0.001; AMI vs SAP, p=0.007, and UAP vs SAP, p=0.001), but that of each large calcification was not significantly different among AMI, UAP, and SAP.
[CONCLUSION] In the culprit lesions of AMI and UAP, calcium deposits more spotty in size and more close to the lumen would be observed frequently. These characteristics of the calcium deposition might play an important role in the pathogenesis of the plaque vulnerability.
Prevalence and Clinical Significance of Layered Plaque in Patients With Stable Angina Pectoris ― Evaluation With Histopathology and Optical Coherence Tomography ―
