A new study led by Gabriel S. Tajeu, assistant professor in the Department of Health Services Administration and Policy, may help lead to changes in how the medical community approaches cardiovascular disease (CVD) prevention in adults.
For decades, the majority of strokes and heart attacks occurred in people with blood pressure readings higher than 140/90 mm Hg. While high blood pressure is still the top risk factor for heart attacks and strokes, the majority of CVD events in the United States now occur in patients with blood pressure lower than 140/90.
That shift occurred as the medical community began better managing hypertension. As a result, many people no longer have high blood pressure but are still considered hypertensive. Although their blood pressure is lowered thanks to hypertension medication, their bodies have still experienced detrimental effects from high blood pressure such as vascular damage. And, they may have other risk factors including elevated cholesterol or diabetes.
These keeps them at a high-risk level for CVD despite their low blood pressure.
“We’re doing a good job managing hypertension in the US, but there is still room for improvement,” said Tajeu. “We need to continue our efforts and now potentially get a little more sophisticated to determine who should be treated for chronic diseases that increase cardiovascular disease risk.”
The study, published in Circulation, presents evidence that treatment of hypertension may need to occur at blood pressure thresholds lower than 140/90. It also asserts that using a 10-year risk assessment for CVD may be more beneficial than looking almost exclusively at blood pressure.
That means calculating a patient’s cholesterol and factoring in whether he or she smokes or has diabetes, for instance, to predict whether they have more than a 7.5 percent chance of having a heart attack or stroke in the next ten years. If the risk is higher than that, the doctor should address those factors to reduce CVD risk. This often includes statin therapy, which uses drugs that lower cholesterol.
“Previously, there was the potential to overlook a patient at risk because their blood pressure was lower than 140/90,” said Tajeu. “You could show up to the doctor with blood pressure around 120 but you could have diabetes, be a smoker or overweight and therefore have a ten-year risk that’s through the roof.”
The study surveyed 31,586 people who were recruited in the early- to mid-2000s for large cohort studies and who hadn’t had any CVD events. Tajeu and his colleagues obtained baseline demographic and clinical information from these cohorts and followed them for an average of 7.5 years, regularly taking blood pressure measurements over that time.
Of those who experienced CVD events during Tajeu’s study, more than 60 percent had blood pressure under 140/90. They also assessed the subjects’ 10-year CVD risk: More than 50 percent of the subjects with blood pressure under 140/90 had a ten-year CVD risk higher than 7.5 percent, but only a little more than a third of them were taking antihypertensive medication.
These findings follow two landmark studies, which Tajeu cites in his own work, demonstrating potential ways to lower CVD risk among adults with blood pressure below 140/90. The Heart Outcomes Prevention Evaluation-3 trial (HOPE-3) suggests that long-term statin medication use in intermediate-risk individuals was well-tolerated and can reduce the risk of a CVD event by 24 percent.
The Systolic Blood Pressure Intervention Trial (SPRINT) shows that treating blood pressure in high-risk individuals to a target blood pressure threshold of 120 mm Hg reduces the risk of an event by 25 percent.
In November, the American Heart Association (AHA) released new guidelines for treatment of CVD risk. Before the guidelines were released, Tajeu stated that he hoped they would address findings in the HOPE-3 and SPRINT studies, along with his own.