According to an investigation, systolic blood pressure levels of less than 120 mm Hg, or higher than 140 mm Hg among individuals who suffered an ischemic stroke, were linked with an increased risk of the individual experiencing an additional stoke in the future. The study is published in the Nov. 16 issue of JAMA, a theme issue on cardiovascular disease and is being released early online to accompany the American Heart Association Scientific Sessions.
“Recurrent stroke prevention guidelines suggest that larger reductions in systolic blood pressure (SBP) are positively associated with a greater reduction in the risk of recurrent stroke and define an SBP level of less than 120 mm Hg as normal. However, the association os SBP maintained at such levels with risk of vascular events after a recent ischemic stroke is unclear,” according to the study.
Bruce Ovbiagele, M.D., M.Sc., of the University of California, San Diego, and his team conducted an investigation to assess the connection of SBP maintained within a low-normal range compared to a high-normal range with clinical outcomes among individuals who recently suffered an ischemic stroke.
The investigation, from Sept. 2003 to July 2006, involved an observational examination of a multicenter trial that consisted of 20,330 individuals aged 50+ from 695 centers in 35 countries with recent non-cardioembolic (not due to small blood clots originating within the heart) ischemic stroke. Patients were followed-up for 2.5 years. Participants were placed into categories based on their average SBP level:
- Very low normal – less than 120 mm Hg
- Low normal – 120 to less than 130 mm Hg
- High-normal – 130 to less than 140 mm Hg
- High – 140 to less than 150 mm Hg
- and very high – 150+ mm Hg
The team discovered that the prevalence of the primary measured outcome (stroke) was highest among participants in the very high SBP level group (14.1%), 8.7% in the high SBP group, 8.0% in the very low-normal SBP group, 7.2% in the low-normal group, and 6.8% in the high-normal group. A similar pattern was observes in the prevalence of the secondary outcome (heart attack, stroke, or vascular death). The very low-normal and very high SBP group had the highest rates of all-cause mortality and death due to vascular causes.
Results from the examination indicated that the risk of stroke was considerably increased in the very low-normal, high, and very-high SBP group compared with the high-normal group. The researchers said:
“Compared with the high-normal SBP level group, risks of the secondary outcome were significantly higher in the very low-normal SBP group, in the low-normal SBP group, in the high SBP group, and in the very high SBP group.
Our results indicate that there may indeed be thresholds of benefit or harm with regard to short-term to longer-term SBP levels after a recent non-cardioembolic ischemic stroke, and imply that clinicians regularly caring for stroke patients in the outpatient setting may need to be vigilant about how low a given patient’s BP is within the normal range to promote favorable outcomes.
In conclusion, these data are hypothesis generating and the notion that aggressively and consistently lowering BP levels within the normal range in the short term to longer term after an index ischemic stroke is not beneficial remains unproven, and will require the conduct of dedicated clinical trials comparing intensive with usual BP reduction in the stable follow-up period after a stroke.
In the meantime, the results of this analysis support aiming for consistent SBP levels of less than 140 mm Hg and less than 90 mm Hg for diastolic blood pressure among recent ischemic stroke patients.”
Written by Grace Rattue