Top Number in Blood Pressure Reading Important, Too

When reading the results of blood pressure measurements, many people focus on the bottom number, or diastolic blood pressure, to determine their risk for heart attack or stroke.

But paying attention to the often-ignored top number, or systolic blood pressure, could be as important, report researchers at Baylor College of Medicine's High Blood Pressure Research Clinic.

"The public's perception is that diastolic blood pressure is more important than systolic blood pressure," said Dr. James L. Pool, professor of medicine and pharmacology at Baylor. "However, people with normal diastolic blood pressure, but even slightly elevated systolic blood pressure, still have a significant risk for heart attack and stroke."

In a blood pressure reading, the systolic number represents the pressure while the heart is beating; the diastolic, or bottom number, represents the pressure when the heart is resting between beats. Blood pressure less than 130/85 is considered a normal reading for adults. A systolic pressure of 130 to 139 or a diastolic pressure of 85 to 89 needs to be watched carefully. A blood pressure reading equal to or greater than 140/90 is considered high blood pressure, also called hypertension.

Baylor is one of 900 centers in the United States participating in a five-year, national study to evaluate the effectiveness of medication on reducing mild systolic blood pressure, heart attack and stroke.

The study investigates patients age 65 and older with mild systolic hypertension of 140 to 159 and vascular disease or diabetes. This study will involve approximately 25,000 patients.

The American Heart Association reports that high blood pressure is the number one modifiable risk factor for stroke and affects more than 60 million people. It also contributes to heart attacks, kidney failure and hardening of the arteries. People with uncontrolled high blood pressure are three times more likely to develop coronary heart disease, six times more likely to develop congestive heart failure and seven times more likely to have a stroke.

"More than half of Americans over the age of 65 have elevated systolic blood pressure but many are not being treated," Dr. Pool said. "New treatments could benefit an enormous percentage of Americans at risk for heart attack and stroke."

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©2006 Texas Medical Center

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