Top Number in Blood Pressure Tells All

To the befuddlement of patients everywhere, blood pressure measurements come in two numbers -- one that's bigger and one that's smaller, such as 120 over 80.

Now, new research confirms that the first number is the more important of the two, and suggests the difference between them -- the little-known "pulse pressure" -- doesn't mean much at all.

"We believe that the number to watch more closely is the higher blood pressure," says study co-author Dr. Eliseo Guallar, a researcher at Johns Hopkins School of Public Health. Why? Because it's a better indication that a seemingly heart-healthy person will die of heart disease, he explains.

Doctors and nurses routinely take the blood pressure of patients by using cuffs to monitor the "push" in the circulatory system. The top "systolic" number measures the pressure when the heart pumps blood out, and the bottom "diastolic" number measures the pressure between the pumps. The pressure doesn't reverse itself between heartbeats, but simply goes down a bit.

High blood pressure is a sign that the heart is working extra hard to push blood through the body. "Too much pressure is bad because it makes your heart overwork, making it more prone to arrhythmias and heart failure," Guallar says. "And as you're pumping blood with more force, you're damaging your arteries."
Stressed-out arteries, in turn, can lead to heart disease, stroke, vascular diseases, and kidney disease.

Doctors have now realized the importance of the systolic pressure after giving too much emphasis to the diastolic pressure, says Dr. Daniel Jones, dean of the School of Medicine at the University of Mississippi Medical Center and spokesman for the American Heart Association.

In recent years, however, some researchers have speculated that the pulse pressure could also be a sign of heart trouble.

Guallar and his colleagues examined the medical records of 7,830 white and black Americans -- both men and women -- who were followed for 15 years. The subjects were aged 30 to 74 and seemed to have no sign of heart disease.

The findings appear in the Nov. 4 issue of the Annals of Internal Medicine.
Those with higher systolic pressure levels were more likely to die of heart disease. Diastolic pressure appeared to possibly play a role in death rates in older patients, as did unusually low blood pressure. But pulse pressure didn't seem to be directly connected to mortality.

"From the scientific standpoint, the really important information is that pulse pressure is not going to be an easy tool for clinicians to use to make decisions about patients," Jones says.

Patients are unlikely to worry about -- or even know about -- their pulse pressures. But they should continue to get their blood pressure checked in the traditional way, Guallar says, "and keep a particular eye on the systolic blood pressure and make sure it's not high."

Doctors say any systolic pressure above 120 is cause for concern.