Should a patient with high lipoprotein (a), or Lp(a), be started on low-dose aspirin?
This is the conundrum facing many physicians and patients, but even getting to that point will require more availability and coverage of tests and a greater appreciation of the risk associated with Lp(a), said cardiologists.
Lp(a): The Silent Risk
On Lp(a) Awareness Day, C. Michael Gibson, MD, MA, CEO of the Baim Institute for Clinical Research, Boston, Massachusetts, and PERFUSE took the opportunity to talk about his experiences with testing on X.
The professor of medicine at Harvard Medical School, also in Boston, said he was surprised to find that he had a very high calcium score, despite a low-density lipoprotein (LDL) cholesterol level of just 70 mg/dL. Eventually, he found out that he had a “very, very high Lp(a),” which was particularly concerning because his grandfather died of a heart attack at 45 years of age.
But how much risk does that represent?
A 2022 consensus statement from the European Atherosclerosis Society (EAS) highlighted that epidemiologic and genetic studies “strongly support a causal and continuous association between Lp(a) concentration and cardiovascular outcomes,” even at very low LDL cholesterol levels.
This is because Lp(a) has proinflammatory and proatherosclerotic properties, and high levels are associated with both micro- and macrocalcification of the aortic valve. Findings from a US registry study also suggest the threshold related to increased cardiovascular risk may differ for primary and secondary prevention populations (J Am Coll Cardiol. 2024 Mar 5;83[9]:873-886).
Lp(a) is, however, genetically determined, and there are no drugs available that directly lower levels, although some are on the horizon. In the meantime, the experts behind the consensus statement recommend that all adults be tested at least once in their lifetime.
Testing Cost and Availability
This recommendation has been translated into guidelines in “many, many” countries, said lead author Florian Kronenberg, MD, MAE, Institute of Genetic Epidemiology, Medical University of Innsbruck, Innsbruck, Austria, but “we are far away from reaching that goal.”
“We’ve got a real problem,” added Stephen Nicholls, MD, PhD, director of the Victorian Heart Institute and a professor of cardiology at Monash University, Melbourne, Australia, as there is “not a country in the world where there’s good access to Lp(a) testing.”
Dr. Kronenberg said that the consensus statement “created a kind of momentum” toward universal testing.
Ulrich Laufs, MD, PhD, professor and chair, Department of Cardiology, University Hospital Leipzig, Leipzig, Germany, agreed, saying that, overall, Lp(a) testing has “increased dramatically,” albeit from “extremely low levels.”
Dr. Kronenberg believes that “we have to be really patient.” He cited a lack of knowledge among physicians as one of the biggest barriers to greater uptake of testing.
“There is still no appreciation of the role of Lp(a),” agreed Alberico L. Catapano, MD, PhD, director of Cardiovascular Research and of the Lipoproteins and Atherosclerosis Laboratory of IRCCS Multimedica, Milan, Italy, and past president of the EAS.
“That’s why it’s not mentioned” to patients, he said. “What is really needed is to inform physician colleagues that Lp(a) is not only a risk factor but is the cause” of atherosclerotic cardiovascular disease (ASCVD).
Dr. Kronenberg said that the pressure for testing can often come from the patient themselves.
Physicians then question why the patient wants to be tested when there are no medications to treat it, he added. “We really tried very hard when we did the consensus paper to say that we should perform the test and give people advice on what to do.”
Dr. Catapano believes that another major obstacle is the cost of the test, which remains high “because very few people do it,” and there is some debate over which test to use.
Taken together, these issues have meant that “payers are really struggling with the idea of funding Lp(a),” said Dr. Nicholls, adding that “there seems to be this fixation on: ‘Well, if you can’t lower Lp(a), why measure it?’ ”
Rather than blame the payers, he says there is a need to educate about the science behind testing and underline that Lp(a) is an “important risk enhancer” for cardiovascular disease.
“Because if we’re going to make people pay out of pocket, then you’re creating a massive equity issue in that only those who can afford the test have it.”