Lp(a): If It Increases Heart Risk, Why Hasn't Lowering It Prevented Heart Attacks?

If you've read our article about lipoprotein(a), or Lp(a), you know that elevated levels are associated with an increased risk of heart attack, stroke, and other cardiovascular problems.

You may also know that Lp(a) is largely inherited, that a routine cholesterol test doesn't measure it, and that levels are generally stable throughout adulthood.

So here's a reasonable question:

If elevated Lp(a) contributes to heart disease, why doesn't lowering it prevent heart attacks?

It sounds contradictory. If something contributes to a disease, shouldn't reducing it reduce the risk?

In principle, yes. But biology and clinical medicine aren't always that straightforward.

Recent research has made this question particularly important. A major clinical trial of a drug designed specifically to lower Lp(a) reduced the measured level but failed to demonstrate a reduction in cardiovascular events.

Understanding why requires looking at the difference between a risk factor, a treatment target, and a proven health benefit.

First, Is Lp(a) Actually Causing Heart Disease?

The evidence that elevated Lp(a) contributes to cardiovascular disease is substantial.

Large genetic studies have shown that people who inherit genetic variations associated with higher Lp(a) levels tend to have greater cardiovascular risk.

This is important because genetic evidence helps distinguish a potentially causal risk factor from something that merely accompanies disease.

Lp(a) appears to contribute to cardiovascular disease through several mechanisms:

• Atherosclerosis: It carries cholesterol into artery walls, contributing to plaque formation.
• Inflammation: It transports oxidized phospholipids, which may promote inflammation within arteries.
• Thrombosis: Its structure may influence processes involved in blood clot formation.

Elevated Lp(a) is also associated with calcific aortic valve stenosis, a condition in which the heart's aortic valve becomes progressively narrowed.

So Lp(a) isn't simply another number that happens to correlate with heart disease. There is strong genetic and biological evidence that it plays a role in the disease process.

But establishing that a risk factor contributes to disease is not the same as proving that a treatment targeting it will prevent that disease.

That's where things get interesting.

The Difference Between Lowering a Risk Factor and Preventing Disease

Consider what happens when someone discovers they have elevated Lp(a).

That person may have had elevated levels since childhood or early adulthood. Over decades, Lp(a) may have contributed to the development of coronary plaque.

By the time the person discovers the problem, substantial atherosclerosis may already exist.

Lowering Lp(a) doesn't automatically remove existing plaque, reverse artery damage, or eliminate the other factors that contribute to heart attacks.

A heart attack can occur when an existing plaque ruptures and a blood clot forms. The process involves several interacting mechanisms, not just one cholesterol-related particle.

Reducing one contributor may help without being sufficient to prevent the event.

This raises an important possibility: the timing of treatment may matter.

Lowering Lp(a) earlier in life, before significant plaque develops, might produce a different result from lowering it in someone who already has established coronary artery disease.

However, this remains a hypothesis. We don't yet have the clinical trial evidence to establish that earlier treatment prevents heart attacks.

Why Niacin Didn't Provide the Answer

Niacin, also known as vitamin B3, can lower Lp(a), sometimes by approximately 20–25%.

For a time, this made it seem like a possible treatment for people with elevated levels.

But two major clinical trials, AIM-HIGH and HPS2-THRIVE, found that adding niacin to statin therapy did not significantly reduce cardiovascular events.

The trials also identified important safety concerns, including problems with blood sugar control and other adverse effects.

Does this prove that lowering Lp(a) doesn't work?

No.

Niacin affects several aspects of cholesterol and lipid metabolism. The trials weren't designed specifically to test whether reducing Lp(a) itself prevents heart attacks in people selected for high Lp(a).

They therefore cannot answer that question conclusively.

Nevertheless, the results are an important reminder that improving a laboratory measurement doesn't necessarily improve a person's health.

Niacin is not recommended specifically to lower cardiovascular risk associated with elevated Lp(a).

The Pelacarsen Trial: A More Direct Test

For years, researchers have been developing drugs specifically designed to lower Lp(a).

One of the leading candidates is pelacarsen, an investigational medication developed by Novartis and Ionis Pharmaceuticals.

Unlike niacin, pelacarsen was designed to target the production of apolipoprotein(a), a key component of the Lp(a) particle.

The aim was straightforward: reduce Lp(a) substantially and determine whether that reduction prevents cardiovascular events.

The Phase 3 Lp(a)HORIZON trial enrolled 8,323 people with elevated Lp(a) and established cardiovascular disease.

Participants received either pelacarsen or a placebo while continuing their usual guideline-directed cardiovascular treatment.

The primary outcome included cardiovascular death, nonfatal heart attack, nonfatal stroke, and urgent coronary revascularization requiring hospitalization.

In September 2026, Novartis announced the results.

Pelacarsen lowered Lp(a), but the trial did not meet its primary endpoint of reducing cardiovascular events compared with placebo.

This was a significant disappointment.

For the first time, a large cardiovascular outcomes trial of a drug specifically designed to lower Lp(a) had failed to demonstrate the expected clinical benefit.

It is important to understand what this result does and doesn't tell us.

It does not prove that Lp(a) is harmless.

It does not prove that lowering Lp(a) can never prevent cardiovascular disease.

But it does mean that substantial Lp(a) reduction has not yet been shown to reduce cardiovascular events in the population studied.

And that's a distinction we shouldn't gloss over.

Why Might the Trial Have Failed?

We don't yet have enough published information to give a definitive explanation.

Several possibilities deserve investigation.

1. Treatment may have started too late.

Participants already had established cardiovascular disease. Many may have accumulated decades of arterial damage before treatment began.

Perhaps lowering Lp(a) earlier, before substantial plaque develops, would produce a greater benefit.

But this has not been demonstrated.

2. Other risk factors may have remained important.

Participants were already receiving guideline-directed treatment, including cholesterol-lowering and blood pressure medications.

Even with excellent management of these factors, cardiovascular risk doesn't disappear.

Lowering Lp(a) may not have been enough to produce a measurable additional reduction in events in this particular population.

3. The duration of treatment may matter.

Atherosclerosis develops over many years. It is possible that the benefits of lowering Lp(a) require a longer period to become apparent.

Again, this is a possibility, not an established explanation.

4. The relationship may be more complicated than expected.

Although genetic and biological evidence strongly supports a causal role for Lp(a), we still need to understand how much cardiovascular risk can be reduced by lowering it at different stages of life and in different patient populations.

The full trial results, including the size of the treatment effect and results in specific subgroups, are important.

At the time of writing, those detailed results have not yet been fully reported.

Does This Mean We Should Stop Worrying About Lp(a)?

No.

A failed drug trial doesn't erase decades of genetic, epidemiological, and biological evidence.

It does, however, change what we can responsibly claim about treatment.

There is a difference between saying:

• Elevated Lp(a) contributes to cardiovascular risk.
• Lowering Lp(a) reduces the number of circulating particles.
• Lowering Lp(a) has been proven to prevent heart attacks.

The first two statements are supported by evidence. The third has not yet been established.

That last distinction is especially important for people who have recently discovered elevated Lp(a) and are understandably looking for ways to reduce their risk.

What Can People With Elevated Lp(a) Do Now?

Although a dedicated treatment with proven cardiovascular outcome benefits remains unavailable, identifying elevated Lp(a) is still useful.

It can help identify inherited risk that might otherwise go unnoticed.

The current approach is to pay particular attention to cardiovascular risk factors for which effective treatments already exist.

These include:

LDL cholesterol and ApoB: Reducing exposure to atherogenic particles is particularly important. Statins, ezetimibe, and other established treatments can reduce cardiovascular risk even though they don't substantially lower Lp(a).

Blood pressure: High blood pressure contributes to cardiovascular disease and should be managed appropriately.

Blood sugar: Diabetes and insulin resistance increase cardiovascular risk.

Smoking: Avoiding tobacco is one of the most important ways to reduce cardiovascular risk.

Lifestyle: Regular physical activity, a nutritious diet, maintaining a healthy weight, and adequate sleep remain important components of cardiovascular prevention.

There is also value in knowing whether close relatives might have elevated Lp(a). Because levels are largely inherited, testing family members can identify risk that might otherwise go unrecognized.

The key is not to assume that an elevated Lp(a) level makes a heart attack inevitable. It is one component of an individual's overall cardiovascular risk.

What Happens Next?

Pelacarsen isn't the only Lp(a)-lowering drug under investigation.

Other approaches include small interfering RNA (siRNA) treatments and drugs designed to prevent Lp(a) particles from assembling.

Several are being studied in large clinical trials.

Importantly, some of these trials are examining different patient populations, including people who have not yet experienced a cardiovascular event.

That could help answer a question the pelacarsen trial cannot fully resolve: Does lowering Lp(a) earlier, before a first heart attack or stroke, prevent those events?

We should also avoid assuming that all Lp(a)-lowering drugs will produce the same clinical results. Different treatments, populations, and trial designs may lead to different outcomes.

The next major results will be important.

The Bigger Lesson: A Better Number Doesn't Always Mean Better Health

There is a broader lesson here that extends beyond Lp(a).

Medicine measures many things: cholesterol, blood pressure, blood sugar, inflammation, and dozens of other biological markers.

Improving those measurements can be useful. But the ultimate objective isn't to produce attractive laboratory results.

It's to help people live longer, healthier lives and prevent serious illness.

A treatment can successfully change a biological measurement without demonstrating that it improves the outcome that matters.

That doesn't make the measurement meaningless. It means we need evidence connecting the treatment to a real health benefit.

For Lp(a), that evidence remains incomplete.

The genetic and biological case that elevated Lp(a) contributes to cardiovascular disease is strong. But the first major trial of a dedicated Lp(a)-lowering drug has not demonstrated the expected reduction in cardiovascular events.

We need more evidence before drawing a final conclusion.

The Watchdog perspective: Take elevated Lp(a) seriously. Don't ignore the risk. But don't confuse lowering a number with proving that you've lowered the chance of a heart attack.

Evidence: MODERATE

Strong genetic and biological evidence supports Lp(a) as a causal cardiovascular risk factor. However, the first major Phase 3 outcomes trial of a dedicated Lp(a)-lowering treatment did not meet its primary endpoint. Detailed results and further trials are needed.