Most heart attacks, strokes, and cases of heart failure don’t just come out of the blue.
A large study by researchers from Northwestern University in the U.S. and Yonsei University in South Korea found that over 99% of people who had these heart problems already had signs of risk years before.
These early signs included things like high blood pressure, high blood sugar, high cholesterol, or a history of smoking.
This research looked at health records of more than 9 million adults in South Korea and almost 7,000 adults in the United States, tracking their health for more than ten years.
The study was published in the Journal of the American College of Cardiology and shows that heart problems are not usually random or sudden. Instead, they build up over time when people have certain health issues that are not well managed.
Heart disease is still the number one cause of death in the U.S. and in many other countries. That’s why understanding these risk factors is so important. Dr. Philip Greenland, a senior author of the study and a cardiology professor at Northwestern University, said the message is clear: we already know the main causes, and we need to focus more on fixing them.
Rather than chasing after new or rare causes, he says we should stick with what we already know works—keeping blood pressure, cholesterol, and blood sugar at healthy levels and avoiding tobacco.
The research team focused on four key warning signs: blood pressure, cholesterol, blood sugar, and tobacco use. They used definitions from the American Heart Association to decide what counts as a “non-optimal” level.
For example, blood pressure at or above 120/80 mm Hg, cholesterol over 200 mg/dL, fasting blood sugar over 100 mg/dL, or any past or current smoking history. These levels are not high enough to be full-blown disease, but they are still risky.
They also looked at more serious thresholds, like blood pressure of 140/90 or more, cholesterol over 240, or fasting glucose over 126—levels that doctors use to diagnose disease.
Across both groups in South Korea and the U.S., the findings were the same. Over 99% of people who had a heart attack, stroke, or heart failure had at least one of these four risk factors in the years before their event. More than 93% had two or more.
High blood pressure was the most common problem. In South Korea, over 95% of patients had it. In the U.S., the number was more than 93%. Even younger women under the age of 60—often thought to be low risk—had at least one non-optimal risk factor before their heart issues began.
Even when the researchers used the stricter clinical thresholds, over 90% of people still had at least one risk factor before their first heart problem.
This study makes it clear that heart problems almost never happen without warning. They are usually the result of years of unhealthy levels of blood pressure, cholesterol, or blood sugar, or from smoking.
The good news is that all of these are things we can change. By catching these risks early and managing them well, we can help prevent most heart attacks and strokes before they ever happen.
The study is published in the Journal of the American College of Cardiology.
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