Heart attacks occurring “out of the blue” may be rarer than some people have thought. A major new study suggests that nearly everyone who experiences a first-time heart attack, heart failure, or stroke has at least one of four factors that put them at increased risk for these conditions: less-than-optimal blood pressure, high cholesterol, elevated blood sugar, or being a current or former smoker.
The study, published Sept. 29, 2025, in the Journal of the American College of Cardiology, included more than nine million adults in Korea and nearly 7,000 in the United States. All had repeated health screenings and were followed for up to two decades. More than 99% of people who developed new coronary artery disease, heart failure, or stroke had at least one of the risk factors before their diagnosis. High blood pressure was the most common, affecting more than 95% of the Koreans and 93% of the Americans with new diagnoses.
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