Stroke patients who lowered their systolic blood pressure below a certain threshold were significantly less likely to have a recurrent stroke caused by a brain bleed compared with those who didn’t lower their pressure that far, according to a study by a UBC neurologist.
Oscar Benavente
The findings, presented at the American Stroke Association’s International Stroke Conference 2013 in Honolulu on Feb. 8, may provide physicians with more definitive treatment targets for patients with a history of subcortical or lacunar stroke. Subcortical stroke accounts for 25 percent of all ischemic strokes and occurs when small, intricate arteries deep within the brain are affected.
“We know keeping blood pressure low protects against a first and a recurrent stroke,” said Oscar Benavente, Professor in the Division of Neurology and research director of the Stroke and Cerebrovascular Health Program at Vancouver Coastal Health. “But we don’t know how low it needs to go, and our study provided some answers.”
In the Secondary Prevention of Small Subcortical Strokes (SPS3) Trial, Dr. Benavente and colleagues divided 3,020 patients into two target groups of blood pressure control, all of whom had previously suffered a small subcortical stroke.
Normal systolic blood pressure (the “top” number in a blood pressure reading) is less than 120 millimeters of mercury (mm Hg). Hypertension or high blood pressure is systolic pressure above 140 mm Hg. Outcomes were compared between those assigned to the “lower target” systolic blood pressure below 130 mm Hg and those treated to achieve a “higher target” between130 mm Hg and 149 mm Hg. At the start of the study, the two treatment groups had similar systolic blood pressure.
They found that:
- After one year of treatment, the group assigned to achieve a lower blood pressure had an average systolic blood pressure of 126.8 mm Hg while the other group averaged 137.8 mm Hg. The average follow-up lasted about 3.7 years.
- Bleeding in the brain, also known as intracerebral hemorrhage, was reduced by 63 percent in those who achieved blood pressure levels below 130 mm Hg of systolic pressure as compared with those who lowered their blood pressure levels between 130 mm Hg and 149 mm Hg.
- Stroke recurrence in either group was lower among those who had greater reductions in their blood pressure levels (2.25 percent per year) compared with those who did not lower their blood pressure as much (2.77 percent per year).
Dr. Benavente noted that the study was not designed to analyze differences in the blood pressure-lowering medicines patients took. Instead it focused on whether one blood pressure benchmark was better than another. However, patients assigned to the lower target took more medications and the distribution of medications by groups were not the same.
“What the study tells us is that a systolic reading of 135 mm Hg may not be enough, but that getting the blood pressure down to below 130 mm Hg may offer our stroke patients greater clinical benefits,” Dr. Benavente said. “I would tell my patients who had this type of stroke to get their blood pressure below 130.”