Abstract Body (Do not enter title and authors here): Background
Lipoprotein(a) [Lp(a)] is causally linked to ASCVD events and aortic stenosis. Some guidelines now recommend screening of Lp(a) at least once in an adult’s lifetime. Currently, there is inconsistency in measurement modality (mg/dL vs. nmol/L), but most guidelines recommending testing in nmol/L due to less variability and improved standardization. We sought to determine the Lp(a) measurement practices, including testing modality and downstream interventions, at a large academic medical institution.

Methods
We evaluated all patient encounter data at UT Southwestern Medical Center (UTSW) between January 1, 2017 to December 31, 2021 for any Lp(a) measurement. High Lp(a) was defined as >50mg/dL or >125 nmol/L. Aggregate data were used to summarize patient demographics, relevant ASCVD co-morbidities, and lipid lowering prescriptions. Chart-review was conducted on patients with high Lp(a) to assess referrals to specialty clinics.

Results
From 2017 to 2021, there were 1,065 Lp(a) measurements among 938 patients, representing fewer than 0.1% of all patients with labs at UTSW. Most were ordered by cardiologists (71%). Lp(a) tests ordered by cardiologists increased 69% annually but remained stagnant for other specialties (figure 1, lines). Median Lp(a) levels across all tests were 17mg/dL and 43nmol/L. Lp(a) was high in 30% of all initial tests. A higher proportion of tests ordered in 2021 by cardiologists (84%) were in nmol/L, the recommended standard, compared with other specialties (55%) (figure 1, bars). Patients with high Lp(a) found by a non-cardiologist were infrequently referred to cardiology (16%), and 53% of patients with high Lp(a) were prescribed lipid lowering therapy within 3 months.

Conclusion
Lp(a) testing at a major academic medical center was rare and only marginally increased during the 5-year study period. Measurement frequency and assay varied widely between specialties, and there were potential opportunities for downstream interventions. In addition to improving awareness of Lp(a), there is an opportunity to standardize practice patterns regarding its measurement and implications.