麻豆传媒

Systolic and diastolic blood pressures both play their part in cardiovascular health, a study showed.

Above the 75th percentile, both systolic blood pressure (HR 1.40, 95% CI 1.38-1.43) and diastolic blood pressure (HR 1.22, 95% CI 1.20-1.24) predicted poor outcomes independent of demographics and coexisting conditions, reported investigators led by Alexander Flint, MD, PhD, of Kaiser Permanente Northern California in Oakland.

New and old hypertension thresholds alike affirmed the association of elevated blood pressure with higher risk of the combined risk of MI, ischemic stroke, and hemorrhagic stroke in multivariable Cox regression analyses:

• Systolic hypertension (≥140 mm Hg): HR 1.18 per unit increase in standardized z score (95% CI 1.17-1.18)
• Systolic hypertension (≥130 mm Hg): HR 1.18 (95% CI 1.17-1.19)
• Diastolic hypertension (≥90 mm Hg): HR 1.06 (95% CI 1.06-1.07)
• Diastolic hypertension (≥80 mm Hg): HR 1.08 (95% CI 1.06-1.09)

"Although systolic blood-pressure elevation had a greater effect on outcomes, both systolic and diastolic hypertension independently influenced the risk of adverse cardiovascular events, regardless of the definition of hypertension (≥140/90 mm Hg or ≥130/80 mm Hg)," the authors concluded in the .

Therefore, "diastolic blood pressure ought not to be ignored," they said, adding that their findings supported recent guideline changes to switch to the lower blood pressure target.

A J-curve for diastolic blood pressure was seen in the analysis, such that there was a higher risk of adverse outcomes at both high and low values.

"We found that the J curve was explained at least in part by the relationship to age and other covariates; in addition, we found that systolic hypertension had a greater effect in the group of participants with lower diastolic blood pressures, an observation that had been previously reported to explain the J curve," the investigators reported.

For the study, Flint's group accessed the electronic medical records of the Kaiser Permanente Northern California health care system's more than 1.3 million adults who had blood pressure readings done in the outpatient setting.

There were more than 36 million blood pressure measurements available; all had been taken by automated blood-pressure cuff.

Adverse events were noted over an 8-year observation period. During that time, predicted risk were as follows for weighted-average blood pressures:

• Systolic blood pressure about 160 mm Hg: 4.8%
• Systolic blood pressure about 136 mm Hg: 1.9%
• Diastolic blood pressure about 96 mm Hg: 3.6%
• Diastolic blood pressure about 81 mm Hg: 1.9%

Limitations of the retrospective study included not counting death in the primary outcome and missing cholesterol data.

However, the study is still important given its emphasis on the importance of both systolic and diastolic blood pressure in future cardiovascular risk, according to Monika Sanghavi, MD, of Penn Heart and Vascular Center in Philadelphia, who was not part of Flint's group.

"As the emphasis shifts from clinic blood pressure readings to ambulatory blood pressure readings in diagnosing hypertension, there is confusion regarding the thresholds for diagnosing. This study supports the idea that a lower threshold to diagnose hypertension of >130/80 mmHg may be appropriate, since it is also a strong predictor of adverse cardiovascular events," she told 麻豆传媒.

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