MANNHEIM, GERMANY – Patients with high lipoprotein(a) (Lp[a]) levels not only have an almost twofold higher coronary plaque burden than those with low levels but also a faster rate of plaque progression, an observational imaging study shows.

This could explain the greater risk for major adverse cardiovascular events seen in patients with high Lp(a) levels, suggests the research, presented during the annual European Atherosclerosis Society Congress.

The team performed follow-up coronary CT angiography (CCTA) on almost 275 patients who had undergone imaging approximately 10 years earlier, finding that almost one-third had high Lp(a) levels.

At baseline, per cent plaque volumes were 1.8 times greater in high Lp(a) patients versus those with low levels of the protein. After 10 years, plaque volumes were 3.3 times larger in patients with high Lp(a) levels.

Over this period, the rate of increase of plaque volume was 1.9 times greater in patients with high Lp(a) levels.

Study presenter Nick S. Nurmohamed, MD, PhD candidate, department of vascular medicine, Amsterdam University Medical Centers, also showed that high Lp(a) levels were associated with a 2.1-fold increase in rates of MACE.

He said in an interview that this finding could be related to Lp(a) increasing inflammatory signaling in the plaque, “making it more prone to rupture, and we saw that on the CCTA scans,” where high Lp(a) levels were associated with the presence of more high-risk plaques.

He added that in the absence of drugs that target Lp(a) levels directly, the results underline the need to focus on other means of lipid-lowering, as well as “creating awareness that Lp(a) is associated with plaque formation.”

Dr. Nurmohamed said that “for the moment, we have to treat patients with high Lp(a) with other risk-lowering therapies, such as low-density lipoprotein [LDL] cholesterol–lowering drugs, and the management of other risk factors.”

However, he noted that “there are a couple of Lp(a)-lowering medications in trials,” with results expected in the next 2-3 years.

“Then we will have the means to treat those patients, and with CCTA we can identify the patients with the biggest risk,” Dr. Nurmohamed added.

Plaque burden

Philippe Moulin, MD, PhD, head of endocrinology and professor of human nutrition at Faculté Lyon Est, Claude Bernard Lyon (France) 1 University, said that the association between Lp(a) and plaque burden has been seen previously in the literature in a very similar study but with only 1-year follow-up.

Similarly, registry data have suggested that Lp(a) is associated with worsening plaque progression over time.

“Here, with 10-year follow-up, [the study] is much more interesting,” due to its greater statistical power, he said in an interview. It is also “well-documented” and uses an “appropriate” methodology.

But Dr. Moulin underlined that the number of patients with high Lp(a) levels included in the study is relatively small.

Consequently, the researchers were not able to look at the level and rate of progression of atherosclerosis between different quartiles of Lp(a), “so you have no dose-response analysis.”

It also does not “establish causality,” as it remains an observational study, despite being longitudinal, “well done, and so on.”

Dr. Moulin added that the study nevertheless adds “one more stone” to the construct of the idea of high risk around high Lp(a) levels, and “prepares the ground” for the availability of two drugs to decrease Lp(a) levels, expected in 2026 and 2027.

These are expected to substantially reduce Lp(a) levels and achieve a reduction in cardiovascular risk of around 20%-40%, “which would be interesting,” especially as “we have patients who have Lp(a) levels four times above the upper normal value.”

Crucially, they may already have normal LDL cholesterol levels, meaning that, for some patients, “there is clearly a need for such treatment, as long as it is proven that it will decrease cardiovascular risk.”

For the moment, however, the strategy for managing patients with high Lp(a) remains to increase the dose of statin and to have more stringent targets, although Dr. Moulin pointed out that, “when you give statins, you raise slightly Lp(a) levels.”

Dr. Nurmohamed said in an interview that “we know from largely genetic and observational studies that Lp(a) is causally associated with atherosclerotic cardiovascular disease.”

What is less clear is the exact underlying mechanism, he said, noting that there have been several imaging studies in high and low Lp(a) patients that have yielded conflicting results in terms of the relationship with plaque burden.

To investigate the impact of Lp(a) levels on long-term coronary plaque progression, the team invited patients who had taken part in a previous CCTA study to undergo repeat CCTA, regardless of their underlying symptoms.

In all, 299 patients underwent follow-up imaging a median of 10.2 years after their original scan. Plaque volumes were quantified and adjusted for vessel volumes, and the patients were classified as having high (≥ 70 nmol/L) or low (< 70 nmol/L) Lp(a) levels.

After excluding patients who had undergone coronary artery bypass grafting, the team analyzed 274 patients with a mean age at baseline of 57 years. Of these, 159 (58%) were men. High Lp(a) levels were identified in 87 (32%) patients.

The team found that at baseline, patients with high Lp(a) levels had significantly larger percent atheroma volumes than those with low levels, at 3.92% versus 2.17%, or an absolute difference of 1.75% (P = .013).

The difference between the two groups was even greater at the follow-up, when percent atheroma volumes reached 8.75% in patients with high Lp(a) levels versus 3.90% for those with low levels, or an absolute difference of 4.85% (P = .005).

Similar findings were seen when looking separately at percentage of noncalcified and calcified plaque volumes as well as when analyzing for the presence of low-density plaques.

Multivariate analysis taking into account clinical risk factors, statin use, and CT tube voltage found that high Lp(a) levels were associated with a greater percent atheroma volume at baseline, at an odds ratio versus low Lp(a) of 1.83 (95% confidence interval, 0.12-3.54; P = .037).

High Lp(a) levels were also linked to a larger percent atheroma volume on follow-up imaging, at an odds ratio of 3.25 (95% CI, 0.80-5.71; P = .010), and a significantly greater change in atheroma volume from baseline to follow-up imaging, at an odds ratio of 1.86 (95% CI, 0.59-3.14; P = .005)

Finally, the team showed that, after adjusting for clinical risk factors, high baseline Lp(a) levels were associated with an increased risk of MACE during the follow-up period, at a hazard ratio versus low Lp(a) levels of 2.10 (95% CI, 1.01-4.29, P = .048).

No funding was declared. Dr. Nurmohamed is cofounder of Lipid Tools. Other authors declare relationships with Amgen, Novartis, Esperion, Sanofi-Regeneron, Ackee, Cleerly, GW Heart and Vascular Institute, Siemens Healthineers, and HeartFlow.

A version of this article first appeared on Medscape.com.

High Lp(a) tied to higher coronary plaque volume, progression