Maybe it was a parent, a sibling, or another close relative, someone who seemed healthy, with no obvious risk factors anyone could point to. Whatever the details, the same question tends to follow: if it happened to them, seemingly out of nowhere, could it happen to me too?
It's a fair question, and increasingly, medicine has a specific answer for part of it. Not every early heart attack comes down to something like diet or smoking. Some of it is written directly into your genes, in a way that's measurable with a single blood test, and that test isn't the one included in a routine checkup.
Worried About Your Family's Heart History?
A Phase 3 clinical trial is recruiting adults with high Lp(a).
Family Heart Disease Isn't Always About Habits
When people talk about heart disease "running in the family," they usually mean shared habits: the same diet, the same smoking history, similar activity levels. That explanation makes sense for a lot of cardiovascular risk, but it doesn't explain everything, and it especially doesn't explain the cases that don't fit the pattern, like a relative who did most things right and still had an event decades earlier than expected.
There's a specific, well-studied genetic risk factor that fits this exact situation better than lifestyle does: a blood particle called lipoprotein(a), or Lp(a). Unlike most heart disease risk, which comes from a mix of many small genetic and lifestyle factors tangled together, Lp(a) is one of the most directly inherited pieces of the puzzle in all of cardiology.
Why This Number Runs So Strongly in Families
Here's a fact that surprises most people, including many who consider themselves fairly informed about cholesterol: your LDL, the "bad cholesterol" number most people fixate on, is only about 15% explained by genetics you can currently test for. Diet, weight, exercise, and medication move it substantially.
Lp(a) is different. Studies consistently put its heritability between 75% and 90%, some even higher. That makes it one of the most genetically determined traits in cardiovascular medicine, on par with eye color in terms of how little daily life changes it.
Why the Same Gene Can Look So Different From Person to Person
The LPA gene has an unusual feature: it contains a repeating genetic segment (called a Kringle IV type 2 repeat) that varies enormously from person to person, more than 40 different versions exist across the population. The number of repeats determines the physical size of the Lp(a) particle your body makes, and here's the counterintuitive part: smaller particles are linked to higher blood levels, while larger ones are linked to lower levels.
This is part of why Lp(a) can vary so widely even within the same family. Two siblings might each inherit a different combination of gene versions from their parents, one landing them in the normal range, the other in the elevated range, all without either of them doing anything differently in terms of diet or exercise.
Your Lp(a) level is also set remarkably early. Research shows the LPA gene essentially reaches its lifelong baseline by early childhood, typically by age 2 to 5. Whatever your number is as a young adult is, for almost everyone, the number you'll carry for the rest of your life.
Who This Might Apply To
Roughly 1 in 5 people worldwide has an elevated Lp(a) level, which makes it common, but it isn't evenly distributed. If a close relative, a parent, sibling, or child, has a confirmed high Lp(a), your odds of also having an elevated level are meaningfully higher than average, since you share a direct genetic source. Certain ancestries also carry a higher average burden: people of South Asian descent, for example, have elevated Lp(a) at roughly 25% versus about 20% globally, which researchers believe partly explains why heart attacks in that population tend to arrive, on average, about a decade earlier than in people of European descent.
Cardiology guidelines generally define a heart attack as "early" or "premature" when it happens before age 55 in men or 65 in women. If a relative fits that description, especially if their other risk factors (blood pressure, smoking, weight) didn't seem to fully explain it, that's specifically the situation in which most guidelines recommend getting your own Lp(a) checked.
What a High Number Actually Means for You
To be clear about what elevated Lp(a) does and doesn't mean: it's a risk factor, not a diagnosis, and not a prediction of when or whether something will happen. It raises your odds of atherosclerosis-related events like heart attack and stroke, independent of your LDL, blood pressure, or other standard numbers, but plenty of people with elevated Lp(a) never have a cardiac event, particularly when everything else about their cardiovascular health is well managed.
That last part matters. One large population study (EPIC-Norfolk) found that people with high Lp(a) who otherwise kept an ideal cardiovascular health profile, healthy weight, good diet, regular activity, not smoking, controlled blood pressure and blood sugar, had only about a third of the cardiovascular risk of people with poor overall heart health, regardless of their Lp(a) level. Genetics sets the starting point here, but daily habits still matter enormously for what happens next.
Related: Why standard prevention doesn't always stop a second heart attack
What to Actually Do With This Information
Ask for the specific test. A standard cholesterol panel does not include Lp(a); it requires its own blood draw, and most people are never offered it unless they or their doctor specifically ask. Since the level is genetically fixed, you typically only need to check it once in your life.
Think of it like cascade screening. In families with certain other inherited cholesterol conditions, doctors already use a practice called cascade screening: once one family member tests positive, close relatives are offered the same test, since the odds of also carrying the trait are high. The same logic applies informally to Lp(a). If one relative has a confirmed high result, it's worth first-degree relatives (parents, siblings, children) asking their own doctor about it too.
Don't panic, act. A high Lp(a) result is information you can use. Management of every risk factor you can influence remains the most evidence-backed response available today.
What's Changing in Treatment
There's no medication approved yet to lower Lp(a) directly, but that's starting to shift. Several drugs designed specifically for this, including options from Eli Lilly, are now in late-stage clinical trials.
One of them, muvalaplin, is an oral medication currently being tested in a Phase 3 study for adults with elevated Lp(a), including those with a strong family history who haven't had an event yet. If you want to see whether it fits your situation or a relative's, the study page has the full eligibility details.
The Bottom Line
An early, seemingly unexplained heart attack in your family often has a specific, testable genetic reason behind it, one that's inherited far more directly than most cardiovascular risk, and one that a single conversation with your doctor and a single blood test can actually clarify. What you do with that information, for yourself and for the relatives who share your genes, is the part that's fully in your hands.
Frequently Asked Questions
Is heart disease always hereditary if it runs in my family? Not always, and it's rarely one single cause. Shared habits like diet and smoking history play a role in many families, but a specific genetic factor like Lp(a) explains a meaningful share of cases that don't fit the lifestyle pattern, especially early or unexplained events.
What counts as an "early" heart attack for this purpose? Most cardiology guidelines define premature heart disease as onset before age 55 in men or 65 in women. If a close relative had an event before that age, it's a reasonable prompt to ask about Lp(a) testing.
If my Lp(a) is high, will my children inherit it too? It is possible, though not a certainty, since each parent passes down one of several possible gene variants. This is exactly why testing close relatives once a high result is found in the family is worthwhile.
Can I lower my Lp(a) with diet or exercise? Not meaningfully. Because it's genetically set, lifestyle changes have very little effect on the number itself, unlike LDL cholesterol. Lifestyle still matters a great deal for the overall risk that number translates into.
How often do I need to test it? Generally just once in your lifetime, since Lp(a) reaches its lifelong baseline level by around age 5 and rarely changes meaningfully afterward.
Is there a treatment for high Lp(a) yet? Not one approved specifically for lowering it. Current care focuses on aggressively managing every other modifiable risk factor. Several Lp(a)-lowering drugs are currently in late-stage clinical trials.