Heart attacks, strokes, and heart failure rarely happen without warning.
In fact, a massive new study shows that more than 99% of people who went on to suffer one of these serious conditions already had at least one health risk factor years before.
The research, led by Northwestern Medicine in the U.S. and Yonsei University in South Korea, analyzed health records from more than 9 million South Korean adults and nearly 7,000 Americans over a period of up to two decades.
The results challenge the idea that cardiovascular disease often strikes healthy people out of the blue.
Cardiovascular disease remains the number one cause of death worldwide.
According to the study, almost all patients had at least one measurable risk factor before their first heart attack, stroke, or episode of heart failure.
These included high blood pressure, high cholesterol, high blood sugar, or smoking.
“We think the study shows very convincingly that exposure to one or more nonoptimal risk factors before these cardiovascular outcomes is nearly 100%,” said senior author Dr. Philip Greenland, professor of cardiology at Northwestern University Feinberg School of Medicine.
“The goal now is to work harder on finding ways to control these modifiable risk factors rather than to get off track in pursuing other factors that are not easily treatable and not causal.”
The researchers used definitions from the American Heart Association to identify “nonoptimal” levels: blood pressure above 120/80 mm Hg, total cholesterol above 200 mg/dL, fasting glucose above 100 mg/dL, or any past or current tobacco use.
These levels may not always be high enough for a diagnosis, but they still indicate added risk.
The findings were strikingly consistent across both countries. In South Korea, more than 95% of people who developed heart disease or stroke had high blood pressure beforehand. In the U.S., that figure was over 93%.
Even among younger women under 60—often thought to be at low risk—over 95% still had at least one nonoptimal factor before their first event.
When the researchers looked at stricter thresholds—such as blood pressure over 140/90 or cholesterol above 240—they still found that at least 90% of patients had one or more major risk factors before developing serious heart problems.
This research, published in the Journal of the American College of Cardiology, highlights how crucial it is to monitor and manage blood pressure, cholesterol, blood sugar, and tobacco use long before they cause damage.
The message is clear: heart disease doesn’t usually strike without warning, and prevention through healthy habits and medical care is almost always possible.
