Around 750,000 Americans have a stroke every year. Of these, 5-14% will have a second stroke within 12 months. But new research suggests that if blood pressure is consistently controlled after an initial stroke, the risk of a second one could be reduced by more than 50%.
The research team, led by Dr. Amytis Towfighi of the Keck School of Medicine at the University of California, recently published their findings in Stroke - a journal of the American Heart Association.
High blood pressure is known to be an important risk factor for stroke. According to the National Stroke Association, those with high blood pressure (140/90 mm/Hg or higher) are one and a half times more likely to have a stroke than those with optimal blood pressure (120/80 mm/Hg).
For their study, the researchers wanted to see whether reducing blood pressure after a first stroke would impact the risk of recurring stroke.
They assessed data from the Vitamin Intervention for Stroke Prevention (VISP) trial involving 3,680 stroke patients aged 35 years or older.
All participants had their blood pressure measured at the baseline of the study, and again 1 month and 6 months later, and every 6 months thereafter up to 24 months. Their blood pressure was considered "controlled" at 140/90 mm/Hg or lower.
'It's not enough to control blood pressure some of the time'
Throughout the study period, fewer than 30% of stroke patients had consistent blood pressure control more than 75% of the time.
Of these patients, those who had high blood pressure at study baseline (defined as systolic blood pressure over 153 mm/Hg) reduced their risk of experiencing a second stroke by 54%, compared with stroke patients who only maintained control of their blood pressure 25% of the time.
These results were true even after the team took other factors into account, such as age, sex and history of stroke and heart disease.
The researchers found that the participants who were most likely to maintain control of their blood pressure consistently were those with a history of heart attacks. The team says this suggests that patients and health care professionals may be more aware of blood pressure control after a heart attack, but are less conscientious after a stroke.
Commenting on the findings, Dr. Towfighi says:
"It's not enough to control blood pressure some of the time. Averages do not take into account variability in blood pressure readings from one check to the next. Fluctuations in blood pressure may be associated with greater cardiovascular risk."
Remote monitoring could enable better blood pressure control
Dr. Towfighi says that since such a small number of stroke patients in this study kept control of their blood pressure more than 75% of the time, "you can only imagine how poor blood pressure control is outside of the clinical trial setting."
Fast facts about stroke
- Stroke kills almost 130,000 Americans every year - the equivalent to 1 in every 19 deaths.
- Around 87% of all strokes are ischemic - when blood flow to the brain is blocked.
- Stroke costs the US around $36.5 billion every year, including costs of health care services, medications to treat the condition and missed days of work.
Based on these findings, Dr. Towfighi says that changes in care may be required to ensure patients maintain consistent blood pressure control. She adds that rather than waiting for clinic visits, patients could check their own blood pressure at home using machines that can transmit data remotely.
There appears to be increasing availability of such devices. Last year, Medical News Today reported on a monitoring device called Scanadu Scout that can read a person's vital signs in 10 seconds and send them to a smartphone.
Most recently, researchers unveiled a health tracker called Wello - a smartphone case that can also measure key vital signs, including blood pressure, heart rate and temperature.
As well as consistently monitoring and controlling blood pressure, Dr. Towfighi says patients should learn how to control overall risk factors for stroke.
She notes that reducing salt intake, eating a healthy diet rich in whole grains, fruit and vegetables, and exercising regularly can all help reduce stroke risk.