Predictors for target lesion microcalcifications in patients with stable coronary artery disease: an optical coherence tomography study

The minimal fibrous cap thickness overlying the necrotic lipid core as well as the presence of macrophages are established characteristics of coronary plaque vulnerability. Recently, the presence of microcalcifications has emerged as a novel feature of vulnerable lesions. However, clinical and plaque morphological predictors of microcalcifications are unknown. In patients with stable coronary artery disease, analysis of plaque morphology (n = 112) was performed using optical coherence tomography prior to coronary intervention to assess predictors of microcalcifications. Microcalcifications were present in 21/112 (18.7%) lesions. Segments with microcalcifications showed a higher total number of calcifications per lesion (6.7 +/- 3.0 vs. 3.2 +/- 2.5, p < 0.001), a lower percent area stenosis (70.9 +/- 11.1 vs. 76.2 +/- 9.7%, p = 0.028), and a higher frequency of macrophage infiltration (66.7 vs. 37.4%, p = 0.014). In lesions with vs. without microcalcifications, macrophage infiltration was characterized by a wider macrophage angle (31.1A degrees +/- 34.4A degrees vs. 13.7A degrees +/- 20.6A degrees, p = 0.003), a higher macrophage index (105.6 +/- 269.0 vs. 31.6 +/- 66.5A degrees A mm, p = 0.020), and an increased frequency of calcium-macrophage co-localization (47.6 vs. 15.6%, p = 0.001). In multivariable logistic regression analysis, the total number of calcifications per lesion (OR 1.53, 95% CI 1.23-1.91, p < 0.001), average macrophage angle (OR 1.28 for 10A degrees-variation, 95% CI 1.03-1.60, p = 0.024), and percent area stenosis (OR 0.59 for 10% increase, 95% CI 0.34-1.04, p = 0.070) were independent predictors for the presence of microcalcifications, whereas the latter did not reach statistical significance. Microcalcifications are related to a less advanced stenosis severity and to extensive plaque inflammation, but not to clinical parameters. Our data may add to the understanding and role of microcalcifications in coronary artery lesions.