Researchers have said that extremely variable blood pressure, and not just high blood pressure, can greatly increase a person's risk of stroke.
To reach the conclusion, UK and Swedish researchers looked at the variability in blood pressure readings at doctors' checks, reports The BBC.
They found those with fluctuating readings at different GP visits had the greatest risk of future stroke regardless of what their average blood pressure reading was.
According to Professor Peter Rothwell of the Department of Clinical Neurology at the University of Oxford, who led the research, the finding has major implications for how GPs spot and treat people at high risk of stroke.
"At the moment, the guidelines for GPs say not to believe a one-off unusual reading, to bring the patient back and measure again, and as long as it's not consistently high, there is no need to treat.
"What we're saying is don't discount that one-off high blood pressure reading."
"If you get rapid fluctuations that can cause turbulent flow of blood which can cause damage and stiffening in the arteries," said Professor Rothwell.