Blood pressure (BP) is measured when the heart is contracting (systolic BP, the first number) and when the heart is resting (diastolic BP, the second number). Ever since the Framingham Heart Study identified that high systolic BP was a stronger predictor of cardiovascular outcomes than high diastolic BP, physicians have focused on lowering high systolic pressures. After the definition of hypertension was lowered from 140/90 millimeters of mercury (mmHg) to 130/80 mmHg in 2017-a controversial move-guidelines continued to emphasize treating the higher number. But a study involving more than 1.3 million outpatients published in the New England Journal of Medicine
on July 18, 2019, may change this practice. In this study, researchers showed that having either high systolic or high diastolic high BP, or both, increased the risk of heart attack and stroke. Additionally, the negative influence of blood pressure on cardiovascular outcomes was seen at 130/80 mmHg, validating the lower threshold for hypertension.