99% strokes are preventable: Study reveals almost all heart attack victims have one of these 4 warning signs

No matter how many diseases we come across, heart attacks remain one of the scariest diseases one could encounter in their lifetime. Cardiovascular diseases (CVDs) – the wide umbrella of heart diseases, heart attack is a part of – are the leading cause of death globally. In fact, a 2025 American Heart Association report, which uses global data, estimates that the global prevalence of CVD was 612.06 million in 2025.

But here’s the thing: Heart attacks don’t always strike with sudden, dramatic chest pain. Often, your body sends quiet, everyday signals, well before a heart crisis hits. In fact, a recent American Heart Association guide lists key symptoms like chest discomfort, upper-body pain, breathlessness, cold sweating, nausea, rapid heartbeat, and lightheadedness – symptoms that may appear gradually or without the classic chest pain.

Now, a new study has revealed that nearly 99% of heart attacks, strokes, or major cardiovascular events that occur in people who already had warning signs – often silent, untreated, or dismissed.

These “red flags” show up years before a crisis, which means that most incidents are not sudden or unpredictable but build up over time. In other words, almost no one’s cardiovascular event is truly “out of the blue.” Researchers found that virtually all patients showed early red flags – particularly 4 warning signs – years before their first major incident.

The landmark research effort, published in the Journal of the American College of Cardiology, studied health data from over 9 million individuals in South Korea and nearly 7,000 in the United States over extended time spans. The researchers tracked who went on to suffer heart attacks, strokes, or heart failure, and looked back to see what risk factors those individuals already carried.

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What they found is both alarming and hopeful: more than99 % of those who experienced major cardiovascular events had at least one of four modifiable warning signs well before their crisis. In many cases, people had two or more.

This research challenges a common belief that heart disease can strike “out of the blue.” Instead, it reinforces the idea that cardiovascular events rarely happen without warning, and many such warnings are actually preventable or manageable – if spotted early enough.

This was the most common warning sign. In both Korean and US cohorts, over 93% of those who later had heart attacks or strokes had blood pressure readings above optimal levels (even if not formally diagnosed as hypertension).

What “elevated” means here is the key clue: many had values above the ideal 120/80 mmHg, though not yet at the clinical threshold used for diagnosis. These intermediate or “non-optimal” levels already increase stress on arteries and the heart.

Why it matters: Over time, higher pressure damages the lining of blood vessels, accelerates plaque buildup, and raises strain on the heart muscle. Left unchecked, it becomes a major trigger for heart attacks and strokes.

Warning signs (often silent): Many people don’t feel symptoms until damage is advanced. Occasional headaches, dizziness, nosebleeds, or shortness of breath may appear, but often no obvious signs.

Abnormal lipid profiles (high LDL, low HDL, high total cholesterol) were present in a large share of those who eventually had cardiovascular events. The study classified many as having “non-optimal” cholesterol levels even before they met criteria for treatment.

These lipid abnormalities accelerate atherosclerosis (clogging of arteries) and narrow blood vessels, which increases the chance of clot formation or rupture.

Warning signs: Usually, no symptoms until the disease is advanced. Rarely, cholesterol deposits (xanthomas) may appear on the skin or around the eyes.

Many participants already had blood sugar levels above ideal – even if they weren’t yet diagnosed with diabetes. That includes prediabetes or borderline values.

Persistently high glucose injures blood vessels, fuels inflammation, and worsens cholesterol profiles, compounding risk. Over the years, this cumulative damage sets the stage for a cardiovascular crisis.

Warning signs: Frequent urination, excessive thirst, fatigue, slow wound healing, blurred vision.

One or more histories of smoking or tobacco use (current or past) were also a nearly ubiquitous factor among the study’s cases.

Tobacco harms blood vessels, increases clotting tendency, raises blood pressure, reduces oxygen delivery, and accelerates arterial damage. Even former smokers carry residual risk, especially if other factors are present.

Warning signs: Often discernible via history rather than symptoms. Effects may include chest discomfort, shortness of breath, or vascular symptoms earlier in life.

What’s striking is not just that these factors appear, but that they often co-exist. Over 93% of people who developed a heart attack or stroke had two or more of these risk factors in the years before their event.

The study authors point out that many previous analyses may have undercounted risk, because they only considered clinically diagnosed levels (e.g., hypertension threshold) rather than broader “non-optimal” levels. This means many people at risk were slipping under the radar.

Because research shows these risk factors are modifiable, the implication is powerful: most heart attacks and strokes are preventable. By identifying and controlling even mild elevations in blood pressure, cholesterol, glucose, and quitting smoking, many crises can be avoided.

First things first, get regular health checkups done. Monitor blood pressure, fasting glucose, cholesterol levels, and smoking status. Encourage family screening. Manage borderline or mildly elevated values. Don’t wait for “full disease.” Even mildly elevated blood pressure, cholesterol, or glucose should prompt lifestyle or medical attention.

Then, adopt a heart-friendly lifestyle. Reduce salt intake, maintain a healthy weight, eat whole grains, fruits, vegetables, and lean proteins. Get your regular doses of exercise (aerobic and strength training). Limit processed foods, refined sugars, and trans fats.

Additionally, avoid – better yet, quit – smoking. It is one of the leading causes of chronic illness, including cancer.

Furthermore, if you detect any of these risk factors, consult a doctor for tailored plans. And finally, share information among your community in order to raise awareness.