Systolic blood pressure levels, but not diastolic blood pressure levels, can predict coronary vascular disease risk. The top number in a blood pressure reading is the best way to determine a man’s heart attack and stroke risk, and should be used to guide treatment, according to a new report. But many doctors continue to treat patients based on the lower number, and the study authors believe this practice should change.
The top number measures systolic blood pressure, the force on blood vessel walls during a heart beat. The bottom, or diastolic, number gauges pressure when the heart is at rest between beats. High blood pressure, or hypertension, is defined as a systolic reading of 140 millimeters of mercury (mm Hg) or greater or a diastolic reading of 90 mm Hg or above.
The diastolic number has conventionally been viewed as a more sensitive indicator of hypertension, and is the reading that commonly influences clinical decision-making regarding degree of disease present and what therapeutic steps should be taken.
In the current study, lead author Dr. Athanase Benetos of the Institut de la Sante et de la Recherche Medicale in Paris, France, and colleagues found that patients with uncontrolled systolic blood pressure were almost 2.5 times more likely to die of heart disease than patients with controlled blood pressure.
But risk of death from cardiovascular disease was not associated with diastolic blood pressure, the investigators report in the March 11th issue of the Archives of Internal Medicine.
"The most important result of this study is that cardiovascular mortality, especially coronary heart disease mortality, is much higher in uncontrolled hypertensive men than in controlled hypertensive men, and that systolic blood pressure levels, but not diastolic blood pressure levels, can predict coronary vascular disease risk independent of age," the authors write.
The study also revealed that 85.5% of men being treated for high blood pressure had uncontrolled systolic or diastolic blood pressure, or both. These patients had a 66% greater risk of death associated with heart disease than those men with controlled blood pressure.
"This clearly confirms that, as measured in a clinical setting, a controlled blood pressure, especially systolic blood pressure, is uncommon," Benetos and colleagues write.
Nevertheless, the authors emphasize that treating systolic blood pressure is of greater value than treating diastolic blood pressure since it has been shown to be a better predictor of death from heart disease.
"Our results show that in clinical practice a well-controlled systolic blood pressure (less than 140 mm Hg) should be the goal of antihypertensive treatment," the researchers conclude.
"As advised in the recent recommendations of the National High Blood Pressure Education program, it is crucial for healthcare providers to focus on systolic blood pressure for diagnosis, staging and therapeutic strategy in hypertension, particularly in the elderly," Dr. Prakash C. Deedwania of the University of California, San Francisco, writes in an editorial accompanying the study.
"It is also important to emphasize that often more than one, but usually two or three drugs are needed to achieve optimal control of systolic blood pressure," he adds.
Archives of Internal Medicine 2002;162:506-508, 577-581.
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