Relationship between left main trifurcation angulation, calcium score, and the onset of plaque formation

Abstract

Background: It has been suggested that a wider left main (LM) bifurcation angle is associated with the development of atherosclerosis. However, the relationship between LM trifurcation angulation and atherosclerosis has not been investigated. Aims: We aimed to investigate the relationship between LM trifurcation angulation and the presence of calcifications in the left coronary artery (LCA) using coronary computed tomography angiography (CCTA). Furthermore, we assessed the relationship between LM trifurcation angulation and the age at which calcification originated. Methods: The LM trifurcation angle and coronary artery calcium (CAC) score in the LCA were measured. Based on observational studies, we assumed that CAC progression is 25% per year on average. Then, we calculated the age at which LCA CAC scores were lower than 0.1 Agatston units. Results: Of 266 patients, 52 patients (mean age of [standard deviation, SD] 61 [6] years; 28 men) with LM trifurcation were included in the study. Calcified plaques occurred in the LCA in 36 patients (69.2%). The mean LM trifurcation angle in patients with a diseased LCA was wider than that in patients with a normal LCA (108° [33°] vs. 91° [28°]; P = 0.04). Pearson correlation coefficient showed that the wider the LM trifurcation angle was, the earlier the calcification in the LCA may be expected (r = –0.34; P = 0.04 with outliers; r = –0.43; P = 0.009 without outliers). Conclusions: A wider LM trifurcation angle is associated with a higher LCA CAC score. Moreover, the LM trifurcation angle has a significant impact on the earlier onset of atherosclerosis.