Doctors follow a standard of care for patients with high blood pressure – or hypertension – which is characterized by systolic blood pressure over 140 millimeters of mercury. But for patients whose blood pressure is above normal but not considered to be high, the course of treatment is not as clearly defined.
Now, researchers at Johns Hopkins University have found that heart CT scans can help physicians determine whether patients who fall within a so-called “gray-zone” of blood pressure readings could benefit from medication. The study – which was published in the journal, Circulation – describes a method which could benefit the third of all US adults which are considered to have prehypertension.
Heart CT scans measure the amount of calcium in arteries of the heart, which can be an indicator of which patients should be treated with antihypertensive medication. If patients have little to no calcium accumulation, they may be able to avoid unnecessarily medicating with blood pressure drugs, depending on whether they have any other cardiovascular risk factors.
“If a healthcare provider wants to target blood pressure in a patient with traditional heart disease risk factors and above-normal blood pressure, he or she can look at coronary artery calcium to help with tiebreaker-like decisions,” said J. William McEvoy, M.B.B.Ch., M.H.S., assistant professor of medicine and member of the Ciccarone Center for the Prevention of Heart Disease at the Johns Hopkins University School of Medicine. “Our study, along with others, such as SPRINT and HOPE, positions cardiac risk and coronary artery calcium as helpful ways to determine if a given patient would either benefit from more intensive blood pressure control or do just fine with a more traditional blood pressure target.”
Currently, risk factor equations are used to determine whether a patient with prehypertension should be medicated, however these tools rely on generalized findings which may not always be applicable on the personal level. Coronary artery calcium scores are currently used to help physicians make decisions based on whether a patient should be put on statins, however its utility in informing prescribing decisions for blood pressure treatments was previously unknown.
In the current study, the Johns Hopkins researchers studied data collected from 3,733 participants in the Multi-Ethnic Study of Atherosclerosis (MESA), in which a baseline blood pressure and coronary calcium score were measured for each. Using the Atherosclerotic Cardiovascular Disease Risk Algorithm, the study investigators also calculated each individual’s heart disease risk using traditional risk factors such as cholesterol levels and family history of disease.
Participants were followed up with on an annual basis, with 642 heart disease-related events – such as heart attack and stroke – occurring within a ten-year period. The study found that participants with a calcium score of zero and high calculated risk of heart disease, had a relatively low rate of actual heart disease-related events. In contrast, participants with a high calcium score but a low predicted risk of heart disease, had a higher actual event rate if their blood pressure was just under the cutoff of 140 millimeters of mercury.
“It may be that if patients are in that blood pressure treatment gray zone with a high risk score but their coronary artery calcium score is zero, then they don’t need to be treated aggressively to 120 millimeters of mercury and can be treated to 140 instead,” said McEvoy. “But if patients have a high calcium score and are in the gray zone, then it would make sense to go with 120 as a treatment goal.”
Because this study was observational in nature, the results will need to be confirmed in a clinical trial before being adopted in practice. In the US, about 70 million adults suffer from high blood pressure, which makes them more susceptible to heart attack, stroke and heart failure.