Lipoprotein (a) is related to coronary atherosclerotic burden and a vulnerable plaque phenotype in angiographically obstructive coronary artery disease

Background: Lipoprotein Lp(a) has been shown to be an independent risk factor for coronary artery disease (CAD). However, its association with CAD burden in patients with ACS is largely unknown, as well as the association of Lp(a) with lipid rich plaques prone to rupture. Aim: We aim at assessing CAD burden by coronary angiography and plaque features including thin cap fibroatheroma (TCFA) by optical coherence tomography (OCT) in consecutive patients presenting with acute coronary syndrome (ACS) and obstructive CAD along with serum Lp(a) levels. Methods: This study comprises an angiographic and an OCT cohort. A total of 500 ACS patients (370 men, average age 66 ± 11) were enrolled for the angiographic cohort and 51 ACS patients (29 males, average age 65 ± 11) were enrolled for the OCT cohort. Angiographic CAD severity was assessed by Sullivan score and by Bogaty score including stenosis score and extent index. OCT plaque features were evaluated at the site of the minimal lumen area and along the culprit segment. Results: In the angiographic cohort, at multivariate analysis, Lp(a) was a weak independent predictor of Sullivan score (p < 0.0001), stenosis score (p < 0.0001) and extent index (p < 0.0001). In the OCT cohort, patients with higher Lp(a) levels (≥30 md/dl) compared to patients with lower Lp(a) levels (<30 md/dl) exhibited a higher prevalence of lipidic plaque at the site of the culprit stenosis (67% vs. 27%; P = 0.02), a wider lipid arc (135 ± 114 vs 59 ± 111; P = 0.03) and a higher prevalence of TCFA (38% vs. 10%; P = 0.04). Conclusions: Among patients with ACS, raised Lp(a) levels are associated with an increased atherosclerotic burden and it identifies a subset of patients with features of high risk coronary atherosclerosis.