Systolic, diastolic BP each tied to adverse CV outcomes
Both systolic and diastolic hypertension independently predict myocardial infarction and strokes, but systolic blood pressure is more strongly linked to adverse outcomes.
That’s according to a study of more than 1 million patients and 36 million outpatient blood pressure measurements published in the New England Journal of Medicine.
Systolic and diastolic hypertension predicted adverse outcomes at cutpoints of 140/90 and 130/80 mm Hg in the large retrospective cohort study, supporting the recent guideline changes that made blood pressure targets more stringent for higher-risk patients, said lead investigator Alexander C. Flint, MD, of Kaiser Permanente Northern California (KPNC) in Oakland.
“While systolic does count for more, in the fact that it is a stronger driver of the risk of heart attack and stroke, diastolic absolutely does as well, and it does so independently. So we ignore our diastolic hypertension at our own peril,” Dr. Flint said in an interview.
Systolic hypertension began to overshadow diastolic after the Framingham Heart Study and others that suggested it is a more important predictor of adverse cardiovascular outcomes, Dr. Flint and coauthors said in a report on their study.
Those findings caused some to say diastole should be abandoned, and led to a “near-exclusive focus” on systolic hypertension in a 2000 advisory statement from the National High Blood Pressure Education Program, they say in their report.
While current guidelines emphasize the importance of both systolic and diastolic targets, many clinicians today often assign little importance to diastolic blood pressure values, the report adds.
“The pendulum needs to swing back, right down in the middle,” Dr. Flint said in the interview.
The study by Dr. Flint and colleagues comprised a cohort of approximately 1.3 million outpatients from KPNC who had at least one baseline blood pressure reading in during 2007-2008, and two or more follow-up measurements between 2009 and 2016, for a total of about 36.8 million data points.
Systolic hypertension burden was linked to the composite of MI or stroke, with a hazard ratio of 1.18 (95% confidence interval, 1.17-1.18; P less than .001) per unit increase in z score, according to results of a multivariable regression analysis. Likewise, diastolic hypertension burden was linked to those adverse outcomes, with a hazard ratio of 1.06 (95% CI, 1.06-1.07; P less than .001).
Put in terms of estimated risk of MI or stroke, patients with a systolic blood pressure around 160 mm Hg – 3 standard deviations from the mean – was 4.8%, compared to a predicted risk of just 1.9% for a systolic blood pressure near 136 mm Hg, the investigators said in their report.
Similarly, predicted risk was 3.6% for a diastolic pressure of about 96 mm Hg, also 3 standard deviations from the mean, and 1.9% for a diastolic BP near 81 mm Hg.
“The two are not that separate,” Dr. Flint said of the risks associated with systolic and diastolic hypertension at that 3-standard-deviation point. Beyond that, increased systolic blood pressure is associated with more risk relative to increased diastolic blood pressure, the logistic regression modeling shows.
Taken together, findings from this large cohort study emphasize the importance of making lifestyle modifications and adjusting medication to ensure that both systolic and diastolic targets are met, according to Dr. Flint.
“Rises in systolic blood pressure count for more in influencing the risk of heart attack and stroke,” he said, “but diastolic independently counts for quite a lot. It’s a close second.”
Dr. Flint reported no disclosures. Senior author Deepak L. Bhatt, MD, MPH, reported disclosures with Amarin, AstraZeneca, Bristol-Myers Squibb, Eisai, Ethicon, Medtronic, Sanofi Aventis, Takeda, The Medicines Company, and others. The remaining authors had no disclosures.
SOURCE: Flint AC et al. N Engl J Med. 2019 Jul 18. doi: 10.1056/NEJMoa1803180.
