These are the 4 risk factors that cause heart attacks

More than 99% of people who suffered a heart attackstroke or heart failure already had at least one risk factor above the optimal level beforehand, a large-scale study led by Northwestern Medicine (United States) and Yonsei University in South Korea.

The study, which analyzed health records over more than a decade of more than 9 million adults in South Korea and nearly 7,000 people in the United States, refutes the notion that these devastating events often affect people without warning signs. The findings are published in ‘The Journal of the American College of Cardiology’.

“We think the study shows very convincingly that exposure to one or more non-optimal risk factors leading up to these cardiovascular outcomes is almost 100%,” says senior author Dr. Philip Greenland, a professor of cardiology at Northwestern University Feinberg School of Medicine. “The goal now is to work harder to find ways to control these modifiable risk factors rather than diverting to other factors that are not easily treatable and are not causal,” he adds.

High cholesterol and glucose: risks that go unnoticed

Greenland and his colleagues selected four main cardiovascular risk factors: blood pressure, cholesterol, blood glucose and smoking. They used the ideal definitions of cardiovascular health from the American Heart Associationwhich describe non-optimal levels as: blood pressure =120/80 mm Hg or under treatment; total cholesterol =200 mg/dL or on treatment; fasting blood glucose =100 mg/dL, diagnosis of diabetes or undergoing treatment; past or current tobacco use.

In a secondary analysis, the team also looked at clinically elevated risk factors, the highest thresholds doctors typically use for diagnosis: blood pressure =140/90, cholesterol =240, glucose =126, and current smoking.

The scientists analyzed health data from more than 9.3 million Korean adults and nearly 7,000 American adults, who were followed for up to two decades. Because these cohorts included repeated medical evaluations, the research team was able to determine the levels of blood pressure, cholesterol, glucose, and tobacco exposure that people had years before their first cardiovascular event.

In the Korean and American cohorts, the results were conclusive: more than 99% of people who developed coronary heart disease, heart failure or stroke had at least one suboptimal risk factor before the event.

More than 93% had two or more risk factors. High blood pressure, or hypertension, was the most common cause, affecting more than 95% of patients in South Korea and more than 93% in the United States. Even in women under age 60 (the group often assumed to have the lowest risk) more than 95% still had at least one suboptimal factor before heart failure or stroke.

When the researchers raised the bar to clinically high levels, the pattern held. Thus, it was confirmed that at least 90% of patients still had at least one important risk factor before their first cardiac event.