Sept. 29 (UPI) -- A new study, released Monday, shows nearly all people who suffer heart attacks or strokes have at least one of four major cardiovascular risk factors beforehand.

Researchers found 99% of participants in the study -- published in the Journal of the American College of Cardiology -- had high blood pressure, high cholesterol, elevated blood sugar or had used tobacco leading up to a cardiac event. High blood pressure was the most common issue. All four risk factors are preventable and can be managed, the study said.

More than 600,000 cases in South Korea and another 1,000 adults in the United States were tracked for up to 20 years. Participants were monitored for blood pressure, cholesterol, glucose and smoke exposure. High blood pressure affected more than 95% of South Korean participants and over 93% of U.S. participants.

"This is important because high blood pressure is fairly easily detectable but it is asymptomatic, so often overlooked," the study's senior author Philip Greenland, professor of preventative medicine at Northwestern University Feinberg School of Medicine, told Medical News Today. "Our findings show how important it is to recognize it and treat it."

According to the American Heart Association, blood pressure over 120/80 should be treated, as should fasting glucose of 100 milligrams per deciliter or more. Total cholesterol of 200 mg/DL or more is another "major risk factor," according to Greenland, who added other "risk factors for cardiovascular disease, like genetics or certain blood markers, are not modifiable."