Despite the clear association between elevated levels of lipoprotein(a) (Lp[a]) and the risk of cardiovascular disease (CVD), the rate of testing for Lp(a) remains suboptimal, with variability that spans ethnicity and geography. Studies presented at the recent American College of Cardiology 75th Annual Scientific Session & Expo (ACC.26) included data addressing the persistently low rates of Lp(a) testing across different settings despite updated guidelines.

Following these presentations, featured expert Nihar Desai, MD, MPH, was interviewed by Conference Reporter Associate Editor-in-Chief Mona Shah, PharmD. Clinical perspectives from Dr Desai on these findings are presented here.

Global epidemiologic studies have looked at Lp(a) levels and noted variation across race, ethnicity, and geography. It is really a function of the fact that Lp(a) levels are mostly based on genetics. For example, individuals of African and South Asian descent seem to have higher Lp(a) levels. In contrast, individuals of East Asian descent and Caucasians from Europe seem to have relatively lower levels. That raises another question: Should there be a single standard cut point for normal or elevated levels depending on race or ethnicity? Right now, based on the way the guidelines have been written and on what we have learned from epidemiological and pathobiological studies, 50 mg/dL (125 nmol/L) is the fairly standard cut point, and anything above 50 mg/dL is considered elevated.

Even though we know a lot about the science behind it, Lp(a) testing is not performed nearly as often as it should be. A relatively recent analysis from 6 academic health systems in California suggested that only 0.3% of the population had undergone Lp(a) testing. That leaves a somewhat substantial gap between the guideline recommendations and what is actually happening in our clinical practices.

Several presentations at ACC.26 addressed Lp(a) testing and disparities. For example, an analysis by Patrick M. Moriarty, MD, and Julie-Ann Dutton from The University of Kansas Medical Center provided a sense of how often Lp(a) testing was done and what the testing rates were across different indications and diagnostic codes. Probably to no one’s surprise, the overall rate of testing was in the low single digits, and there was also substantial variation. Patients who were most likely to be tested were those with coronary artery disease or peripheral arterial disease. Those with aortic valve stenosis or stroke were relatively less likely to be tested. I think that this is an important contemporary look at what is happening at a large academic medical center, demonstrating the low use of testing with some variation based on clinical history. I also think that it will be important for us to see how this evolves over time now that we have guideline recommendations advocating for Lp(a) and a growing awareness of the potential importance of Lp(a).

Shifting from the use of testing to variations in testing, another analysis presented at the ACC.26 meeting leveraged the TriNetX global database (TriNetX, LLC). Pei Lun Lee, MD, and colleagues looked at patients with atherosclerotic CVD (ASCVD) and then at testing rates and patterns for both Lp(a) and CRP. In this broad global database with more than 1.6 million patients with ASCVD, 63.9% were White, 13.7% were Black, 7.4% were Asian, and 5.1% were Hispanic. Overall, less than 5% had undergone Lp(a) testing, while nearly 50% had CRP measured. Over time, Lp(a) testing increased modestly across all race and sex subgroups, and CRP testing actually declined among White, Black, and Hispanic patients but increased among Asian patients. As previously noted, there are important differences in Lp(a) concentrations by race, ethnicity, and geography. This TriNetX analysis also suggests a difference in testing rates across races and ethnicities. The authors concluded that, in patients with established ASCVD, Lp(a) and CRP testing rates remain suboptimal, highlighting the need for stronger advocacy and implementation in clinical practice. We have gaps between where the science is, where the guidelines are, and what is happening in day-to-day practice.

There was a related poster by Kevin Maymi-Quintana, MD, et al presented at ACC.26 looking at disparities in Lp(a) testing among Latino patients specifically. This study also leveraged the TriNetX database and looked at adults with ASCVD across 87 US health systems. Patients were stratified by ethnicity, and Latino individuals were found to be significantly less likely to have Lp(a) testing compared with non-Latino individuals. This highlights a gap that has important implications in terms of disparities but also in the application of guideline-recommended interventions, screening, and optimizing CV risk assessment.

Ultimately, the only way to be forward looking about the potential future use of any Lp(a)-lowering therapy is, of course, to do the testing in the first place. If there are gaps and ethnic disparities in testing, that might have important implications for the use of any Lp(a)-lowering therapy. The gap in Lp(a) testing may be the result of several additional factors coming together as well. Some practitioners may not be fully aware of what Lp(a) is, what the epidemiology tells us, how they should test for it, how they should interpret the results, and what units they should be looking at. So, I do think that there is a bit of an educational effort required to really try and get this right.