Lipoprotein(a) Levels and Major Adverse Cardiovascular Events in Alberta, Canada: A Retrospective Cohort Study

Background Elevated lipoprotein(a) (Lp(a)) is a key contributor to residual cardiovascular risk in secondary prevention populations. However, Lp(a) testing rates remain low despite guideline recommendations, highlighting a gap in atherosclerotic cardiovascular disease (ASCVD) management. The purpose of this study was to characterize patients with Lp(a) testing and established ASCVD and quantify the risk of subsequent major adverse cardiovascular events (MACE). Methods A retrospective cohort study was conducted using administrative health data from Alberta, Canada. Patients were indexed on their first ASCVD event between January 1, 2015 and September 30, 2022. Time-to-first MACE was assessed using Kaplan–Meier and Cox regression models, grouped by different Lp(a) thresholds. Multivariable models were adjusted for significant characteristics identified through univariable analysis. Results The study cohort included 6891 patients with a mean age of 60.0 years (standard deviation: 12.2), 35.9% female; 5163 had an Lp(a) level ≤ 50 mg/dL (∼120 nmol/L), and 1728 had an Lp(a) level > 50 mg/dL. At 8 years post-index, the MACE-free probability (95% confidence interval [CI]) was 76.3% (73.7%-79.0%) for ≤ 50 mg/dL, 64.7% (58.9%-70.4%) for > 50 mg/dL, 60.7% (53.4%-68.0%) for > 70 mg/dL (∼168 nmol/L), and 57.1% (46.8%-67.3%) for > 90 mg/dL (∼216 nmol/L). The adjusted hazard ratio (95% CI) for Lp(a) > 50, > 70, and > 90 mg/dL (vs the corresponding reference category) was 1.49 (1.29-1.73), 1.56 (1.33-1.83), and 1.60 (1.33-1.93), respectively. Conclusions Patients with elevated Lp(a) level and ASCVD had increased risk of MACE. These findings support broader, routine Lp(a) testing to enable earlier intervention and inform use of targeted Lp(a)-lowering therapies in Canada.