Stroke risk can be better predicted through measuring variations in patients' blood pressure, rather than taking high-average readings, a study in The Lancet journal has found.
These variations can also show how vulnerable a person is to major heart problems and angina chest pains.
The research may pave the way for a better understanding of how to prevent people having strokes and heart attacks. Treatment guidelines now need to be reviewed to emphasise the importance of blood pressure changes, the researchers said.
Four groups of 2,000 patients who had all suffered a "mini-stroke" were involved in past studies, and the researchers, based at the University of Oxford, looked at how fluctuations in their blood pressure had increased or decreased their risk of further stroke.
Those whose systolic blood pressure - when each "surge" of the beating heart is recorded - varied the most were found to be six times as likely to suffer a stroke than those with the least varied systolic blood pressure.
Patients who had the highest average blood pressure after seven clinic visits were found to be 15 times more likely than the others to have a stroke.