Pelacarsen Misses the Mark in Lp(a) Outcomes Trial
Does This Mean Lp(a) Doesn't Matter?
Bottom Line
A medication that lowers Lp(a) by up to 80% didn't significantly lower MACE (Major Adverse Cardiovascular Events).
This shocked cardiologists, patients, and me.
Lipoprotein(a) — "Lp(a)," said out loud as "L-P-little-a" — is an LDL-like particle with an extra protein tail called apolipoprotein(a). That extra protein makes it stickier, more inflammatory, and more prone to promoting clot formation than an ordinary LDL particle.
It's inherited. Genetics determines about 90% of your level. Diet, exercise, and weight loss barely move it.
It's common. About 20% of people worldwide have elevated levels, and closer to a third of people with premature heart disease have increased levels.
There's no current FDA-approved treatment.
That's why Lp(a) has gotten so much attention.
For years, the honest answer to "what do I do about my high Lp(a) number?" has been: control everything else aggressively, and wait for the drugs.
In today's newsletter, we will cover the initial press release for a Phase 3 trial that has shown a reduction in Lp(a).
Lowering Lp(a) doesn't automatically mean fewer heart attacks.
Pelacarsen Misses the Mark in Lp(a) Outcomes Trial
We know Lp(a) is more atherogenic on a per-particle basis. Reducing Lp(a) with medication didn't reduce MACE.
At the end of the day, the mechanism is a signal, but does it reduce heart attacks and strokes?
Lp(a)HORIZON enrolled 8,323 patients with established cardiovascular disease and an Lp(a) of 70 mg/dL or higher.
It ran for more than six years. Half received monthly injections of pelacarsen, which reduced Lp(a), and half received placebo.
Everyone in the trial was already on statins or other lipid-lowering therapy, blood pressure medication, etc.
Once medical therapy is optimized, does lowering Lp(a) in addition further prevent heart attacks and strokes?
The primary endpoint was a composite of cardiovascular death, non-fatal heart attack, non-fatal stroke, and urgent coronary revascularization requiring hospitalization.
The drug lowered Lp(a). It did not lower events.
Novartis's chief medical officer put it plainly: these weren't the results they hoped for. The full data will be presented at an upcoming medical conference, and until then, we're all working from a press release.
Does This Mean Lp(a) Doesn't Matter?
"Lp(a) doesn't matter."
That's the conclusion from the headlines. Let's talk about what the findings mean and don't mean.
The evidence that Lp(a) causes cardiovascular disease is strong.
Mendelian randomization studies, where people are effectively randomized by nature to high or low lifetime Lp(a), consistently show that those born with high levels have more heart disease.
One trial hasn't erased that evidence.
This trial tested a more specific hypothesis: that lowering Lp(a) pharmacologically in adults with established disease for about 4 years reduces events. That hypothesis failed.
There are at least three explanations:
Too late. These were patients who already had disease. Lp(a) does its damage across decades. A few years of treatment in a 65-year-old with established plaque may simply be too little, too late.
The benefit got washed out. Everyone was already on lipid-lowering therapy, which significantly reduced risk. Therefore, the added benefit from lower Lp(a) may be too modest to detect in this specific patient population.
The absolute reduction wasn't big enough. Pelacarsen lowers Lp(a) by about 72–80%. Someone starting at 250 mg/dL who drops 75% still ends up around 60 mg/dL — above the risk threshold.
We will wait until the full dataset is presented.
The Bottom Line
Though these aren't the results we hoped for, here's what hasn't changed.
Know your numbers.
Reducing atherogenic particles (ApoB or LDL-P) has been shown to reduce MACE.
Two large outcomes trials are still running. OCEAN(a)-Outcomes is testing olpasiran in roughly 7,300 patients, with results expected around 2027. ACCLAIM-Lp(a) is testing lepodisiran, which lowers Lp(a) by about 94% with dosing as infrequent as once or twice a year.
Those trials just got much more interesting, and much more uncertain.
Does one trial set the standard? No.
A hypothesis that everyone believed — including me — was tested properly in 8,000 patients over a handful of years, and it didn't hold.
That's not a failure of the field. That's the field working. I'd rather have a hard answer than an assumption.
We'll cover the full data when it's presented.
Knowing Your ApoB Levels
Apolipoprotein B (ApoB) is not included in a standard lipid panel and is rarely included on routine annual labs.
That's starting to change. The new 2026 ACC/AHA cholesterol guidelines now formally recommend ApoB testing to refine risk assessment in certain patients — because ApoB directly quantifies the number of atherogenic lipoproteins, providing a more accurate measure of atherogenic particle burden than LDL-C.
Essentially, ApoB counts the actual number of artery-clogging particles in your blood, which can be a more accurate measure of risk than LDL-C alone.
Function Health is an all-in-one health platform that starts with 160+ lab tests, covering your heart, hormones, liver, kidneys, thyroid, immune system, cancer signals, toxins, and key nutrients.
That’s about 5× as much testing as standard primary care labs—bloodwork that would normally cost thousands of dollars out of pocket.
Scheduling is simple, with 2,000+ lab locations across the U.S., and most visits take around 15 minutes.
If you are interested in knowing your ApoB level, see if Function is a good fit for you.
* Disclaimer: This blog is for general informational purposes only and does not constitute the practice of medicine, nursing, or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. The use of information on this blog or materials linked from this blog is at the user’s own risk. The content of this blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay seeking medical advice for any medical condition they may have and should consult their healthcare professionals for any such conditions.
