Although lowering blood pressure after a stroke has been known to reduce the risk for another stroke, a heart attack, and other vascular events, the impact of keeping blood pressure consistently controlled after a stroke had not been previously studied. Evidence from sufferers of hypertension and coronary heart disease has suggested that consistency of blood pressure control was related to lower risks of death, non-fatal heart attacks, and stroke for that population, and that this reduction in risk from consistent blood pressure was independent of the effects of lowering systolic blood pressure. However, there was no evidence of whether consistency of blood pressure was also related to more positive health outcomes for stroke victims.
Researchers examined the data from a study of 3,680 ischemic stroke victims, which measured patients’ blood pressure for two years following their stroke. For this study, having blood pressure under control was defined as having blood pressure of 140 over 90 at a clinical checkup. Among study participants, there was considerable variation in the proportion of visits when the participants had their blood pressure under control; 30 percent had their blood pressure under control for more than 75 percent of their follow-up visits, 19 percent of participants had it under control in 50 to 75 percent of their visits, 16 percent had it under control in 25 to 49 percent of their visits, and 35 percent had their blood pressure under control in less than 25 percent of their checkups.
Since low baseline systolic blood pressure also impacted the risk of recurring stroke, or death from a heart attack, stroke, or other vascular cause, the impact of consistent control of blood pressure was examined at various levels of baseline systolic blood pressure. When examined this way, consistent control of blood pressure did not affect the rate of adverse vascular health outcomes for individuals with a baseline systolic blood pressure below 132. However, above 132, the impact of having blood pressure consistently under control became significant, For example, individuals with baseline systolic blood pressure of 153 and with blood pressure controlled for over 75 percent of their visits had almost half the risk of stroke and half the risk of death from heart attack, stroke, or another vascular cause.
Among the individuals in this study, the researchers also found that those with a history of heart attacks were more likely to have more consistent blood pressure control than other participants. They suggest that this may reflect patients being more aware of the importance of controlling blood pressure after a heart attack. The lower rates of control for stroke victims who had not suffered a heart attack may reflect either a lack of knowledge or a lack of diligence on their part. Either way, this suggests the need for better public health education on the importance of blood pressure control following a stroke.
Taken together, these findings led the authors to conclude, “These findings highlight the importance of ensuring BP [blood pressure] is controlled at each poststroke clinical encounter, particularly among patients with elevated baseline SBP [systolic blood pressure].” They also note that with less than one third of the study participants having blood pressure under control more than 75 percent of the time, there is considerable room for improvement on this risk factor. Furthermore, with the availability and low cost of home blood-pressure monitors and mobile health technology, tracking the consistency of blood pressure control can be done frequently and conveniently.
Towfighi A, Markovic D, and Ovbiagele B. Consistency of blood pressure control after ischemic stroke: prevalence and prognosis. Journal of the American Heart Association. (2014). DOI: 10.1161/STROKEAHA.113.001900