Nearly Every First Heart Attack and Stroke Was Preceded by a Known Risk Factor

CATEGORY: HEART & CIRCULATION

More than 99% of people who had a first heart attack or other coronary event, stroke, or episode of heart failure—a condition in which the heart cannot pump well enough to meet the body’s needs—had at least one elevated risk factor beforehand: blood pressure, cholesterol, blood sugar, or tobacco use, according to a study of more than 9.3 million adults. The finding challenges the common belief that heart attacks usually strike without warning—in these data, an event almost never occurred in someone whose four basic numbers had all stayed in the optimal range.¹ The authors say the results also counter recent studies suggesting heart disease often occurs without traditional risk factors.¹

Stricter Cutoffs Than a Diagnosis Requires

The researchers deliberately used stricter cutoffs than the ones used to diagnose disease. Blood pressure counted as elevated at 120/80 mm Hg or higher—below the level where high blood pressure is diagnosed—or if a person was on blood pressure medication. Total cholesterol counted at 200 mg/dL or higher, blood sugar at the prediabetes level or higher—meaning blood sugar above normal but short of diabetes—and any past or current smoking counted as tobacco exposure. Many adults would consider these levels unremarkable, which is part of the point: risk appears to begin building below the thresholds where diagnoses are made.

9.3 Million Koreans and 6,800 Americans

The study followed two large groups on opposite sides of the world: about 9.3 million South Korean adults tracked through national health screenings and insurance records from 2009 to 2022, and about 6,800 U.S. adults followed with detailed periodic exams from 2000 to 2019. When a participant had a first heart attack, stroke, or new heart failure, the researchers looked back at the health measurements recorded in the years before it. The analysis rested on 601,025 cardiovascular events in the Korean records and 1,188 in the U.S. group.¹ In both countries the pattern was the same: over 99% of these events happened in people who had at least one elevated factor beforehand, and more than 9 in 10 had two or more. Elevated blood pressure was the most common, present in roughly 96% of cases.¹

Most People With a Risk Factor Never Have an Event

This was an observational study, so it shows an association, not proof that any single factor caused any single event. The finding also does not run in reverse: having an elevated risk factor is extremely common, most people who have one will never have a heart attack, and a blood pressure reading above 120/80 is not a diagnosis or a prediction. What the study documents is how rarely the opposite occurs—cardiovascular events in people whose blood pressure, cholesterol, blood sugar, and smoking history were all optimal were vanishingly rare. That held across groups: even among women under 60, where elevated factors were least common, more than 95% of heart failure and stroke cases were still preceded by at least one.

Earlier Analyses Landed at 81% to 94%

Earlier research pointed the same way, with smaller numbers. Two large 2003 analyses using the thresholds at which conditions are formally diagnosed, rather than the stricter cutoffs used here, found at least one major risk factor beforehand in 87% to 94% of fatal coronary events, and in roughly 81% of men and 85% of women who already had heart disease.²³ How close the figure sits to 99% depends heavily on how low the threshold for elevated is set.

Key Takeaways

• Across more than 9.3 million adults in two countries, over 99% of first heart attacks, strokes, and heart failure cases occurred in people with at least one previously elevated risk factor—blood pressure, cholesterol, blood sugar, or smoking.
• Elevated blood pressure was the most common prior factor, present in roughly 96% of cases, and more than 9 in 10 people had two or more factors before their event.
• The study is observational and looks backward from events: it shows these events almost never happen without prior risk factors, not that an elevated factor makes an event likely—most people with one never have a cardiovascular event.

References

1. Lee H, Huang X, Khan SS, et al. Very High Prevalence of Nonoptimally Controlled Traditional Risk Factors at the Onset of Cardiovascular Disease. Journal of the American College of Cardiology. 2025;86(14):1017–1029. link
2. Greenland P, Knoll MD, Stamler J, et al. Major risk factors as antecedents of fatal and nonfatal coronary heart disease events. JAMA. 2003;290(7):891–897. link.
3. Khot UN, Khot MB, Bajzer CT, et al. Prevalence of conventional risk factors in patients with coronary heart disease. JAMA. 2003;290(7):898–904. link.