June 10 (UPI) -- Slight increases in systolic blood pressure, even in the normal range, increase a person's risk for heart attack or stroke, according to a study published Wednesday by JAMA Cardiology.
In fact, the risk for heart disease increases nearly two-fold for every 10 mmHg. rise in systolic blood pressure above 90 mmHg., researchers report in the new study.
"These findings suggest that adhering to a healthy diet, lifestyle and exercise regimen to prevent an increase in your systolic blood pressure is likely beneficial for keeping your cardiovascular disease risk as low as possible," study co-author Dr. Seamus P. Whelton, an assistant professor of cardiology at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease, told UPI.
Systolic blood pressure -- the "top," or first, number in a reading -- measures the amount of pressure in the arteries as the heart muscle contracts, according to the American Heart Association. For example, a reading of 120/80 mmHg. means that systolic blood pressure is 120 mmHg.
Historically, the "normal" or healthy range for systolic blood pressure has been considered to be between 90 mmHg. and 120 mmHg., according to the AHA, which estimates that more than 100 million Americans have high blood pressure, or hypertension.
For the new study, Whelton and his colleagues reviewed data from the Multi-Ethnic Study of Atherosclerosis on 1,457 participants with no history of atherosclerotic cardiovascular disease, high cholesterol, diabetes or smoking. Atherosclerosis, or hardening of the arteries, is the underlying cause of roughly half of all heart diseases.
Of the 1,457 participants, 894 -- or just over 60 percent -- were women, and most participants were in their mid to late 50s at the start of the study, the researchers said. The heart health of most participants was tracked for about 15 years.
Overall, participants' risk for heart disease increased by more than 50 percent for every 10 mm Hg rise in systolic blood pressure, the researchers found.
Compared to participants with systolic blood pressure levels between 90 and 99 mmHg., those with systolic blood pressures between 100 and 119 mmHg. were three times as likely to be diagnosed with some form of heart disease, researchers observed.
Meanwhile, participants with systolic blood pressures between 120 and 129 mmHg., were five times more likely to be diagnosed with heart disease than those with systolic blood pressures between 90 and 99 mmHg, they said.
"There is a continuous increase in the risk for heart attack and stroke with higher systolic blood pressures, starting from a systolic blood pressure as low as 90 mmHg.," Whelton said.
Risk for heart disease increases "even when you have a systolic blood pressure in the normal range," he added.