A single blood test can explain a heart attack in someone who is not overweight, does not smoke and has normal cholesterol levels. This is lipoprotein(a), or Lp(a) – an inherited particle that carries cholesterol and can promote plaque buildup, inflammation and clot formation in blood vessels.
Jennifer Ray’s case shows why this risk often goes unnoticed. In October 2019, when she was 41, she felt anxiety, pain in her arms and tightness in her chest. Ray, who doesn't smoke, is a vegetarian and believes her cholesterol is good, initially mistook the symptoms for a panic attack.
The next morning, an electrocardiogram showed a possible heart attack. She later went into cardiac arrest and doctors found her anterior descending artery was 95 percent blocked. After an emergency stent was inserted, Ray recovered, but a follow-up test showed an Lp(a) of 184 nmol/L.
“If I had known I had high Lp(a), I would have taken the symptoms of a heart attack more seriously and not waited,” Ray told The Telegraph. Her father, sister and son also have high levels, highlighting the hereditary nature of the indicator.
Risk not seen in standard lipid profile
Lp(a) is similar to LDL cholesterol, but it contains an additional protein - apolipoprotein(a). It makes it easier for the particle to stick to the artery wall and can increase inflammation and clotting. “It's a slightly more dangerous version of what we call LDL cholesterol“, says Riyaz Patel, professor of preventive cardiology at University College London.
According to the US Centers for Disease Control and Prevention, values above 125 nmol/L are considered high. The American Heart Association recommends that every adult have their Lp(a) tested at least once in their lifetime, as the test is not usually included in a standard lipid profile. High levels often do not cause symptoms.
An analysis of data from more than 20,000 people linked levels above 175 nmol/L to a 31 percent higher risk of heart attack, a 64 percent higher risk of stroke, and a 49 percent higher risk of death from cardiovascular disease within four years.
Treatment still limited
Unlike LDL cholesterol, Lp(a) does not significantly decrease with diet or physical activity. With a high score, doctors focus on overall cardiovascular risk, including controlling LDL cholesterol, blood pressure, diabetes and smoking.
“The reason it hasn't been widely studied is that right now there's not much we can do if the score is high,“ says Michael Shapiro, a professor of cardiovascular medicine at Wake Forest University School of Medicine. He emphasizes that lowering LDL remains important because there are many more LDL particles in the blood than Lp(a).
Pelacarsen - a drug that blocks the production of Lp(a) - reduced its levels by more than 80 percent in a large clinical trial, but it didn't show the expected reduction in serious cardiovascular events. Shapiro says this could mean that such therapies should be applied earlier, before plaque buildup has caused permanent damage.
Trials of other gene-targeted drugs being developed by Amgen and Eli Lilly are ongoing. While the results of those are not available, high Lp(a) remains an important hereditary risk factor that can be detected with a single specialized blood test.
Sources: telegraph.co.uk, health.yahoo.com