A blood pressure reading only slightly above normal may increase stroke risk, a surprising new study suggests.
Blood pressure levels ranging from 120/80 to 139/89 raised the risk of stroke by 66 percent, according to the study published Wednesday in Neurology. In a smaller group of patients with blood pressures between 120/80 and 129/84, the risk was still increased by 44 percent.
“Even low-range prehypertension, which is defined as ‘normal blood pressure’ in some hypertension guidelines, could increase the risk of stroke significantly,” said cardiologist Dr. Yuli Huang, the study’s lead author and researcher at the Nanfang Hospital of the Southern Medical University in Guangzhou, China.
Data for the new research was combined from 19 previous studies, involving 762,393 individuals who were followed from four up to 36 years. The prevalence of prehypertension ranged from 25 to 54 percent.
Blood pressure is considered optimal if it is below 120/80 mm Hg. Hypertension is diagnosed when blood pressure is at or above 140/90. Everything in between is defined as prehypertension.
Current guidelines do not recommend medical treatment for prehypertension. Instead lifestyle changes, such as maintaining a healthy weight, reducing salt intake and increasing exercise, are advised to bring pressure down.
The new findings add to growing evidence linking elevated blood pressure levels to stroke risk, but are “not sufficient to change current guidelines,” said Dr. Gregg Fonarow, a professor and co-chief of clinical cardiology at the David Geffen School of Medicine at UCLA.
Clinical trials are needed to prove whether medication for prehypertension will bring down stroke risk, Fonarow said.
Still, for some prehypertensive patients, it may make sense to try medication, said Dr. John Schindler, an interventional cardiologist and an assistant professor of medicine at the University of Pittsburgh Medical Center.
He points to a study in patients with diabetes and prehypertension, where stroke risk was lowered by 40 percent among those who received treatment that brought systolic blood pressure to less than 120.
Medications may have side effects, but “I tell my patients, ‘I’m not afraid of death,’ ” said Schindler. “What I am afraid of is stroke. I wouldn’t wish it on my worst enemy.”