Coronary artery calcification and plaque stability: an optical coherence tomography study

Background: Coronary artery calcification (CAC), a surrogate of atherosclerosis, is related to stent underexpansion and adverse cardiac events. However, the effect of CAC on plaque stability is still controversial and the morphological significance of CAC has yet to be elucidated.Methods: A retrospective series of 419 patients with acute coronary syndrome (ACS) who underwent optical coherence tomography (OCT) were enrolled. Patients were classified into three groups based on the calcification size in culprit plaques and the features of the culprit and non culprit plaques among these groups were compared. Logistic regression was used to analyze independent risk factors for culprit plaque rupture and the nonlinear relationship between calcification parameters and culprit plaque rupture. Furthermore, we compared the detailed calcification parameters of different kinds of plaques.Results: A total of 419 culprit plaques and 364 non-culprit plaques were identified. The incidence of calcification was 53.9 % in culprit plaques and 50.3 % in non-culprit plaques. Compared with culprit plaques without calcification, plaque rupture, macrophages and cholesterol crystals were more frequently observed in the spotty calcification group, and the lipid length was longer; the incidence of macrophages and cholesterol crystals was higher in the macrocalcification group. Calcification tended to be smaller in ruptured plaques than in non-ruptured plaques. Moreover, the arc and length of calcification were greater in culprit plaques than in non-culprit plaques.Conclusions: Vulnerable features were more frequently observed in culprit plaques with spotty calcification, whereas the presence of macrocalcification calcifications did not significantly increase plaque vulnerability. Calcification tends to be larger in culprit plaques than in non-culprit plaques.