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Study Raises Caution About Lowering Elderly Blood Pressure Too Far

November 18, 1992

NEW ORLEANS (AP) _ Well-meaning attempts to reduce elderly people’s high blood pressure with medicine may do more harm than good when levels go too low - even when they decline to seemingly normal readings, a study suggests.

The study found that people’s risk of dangerous irregular heartbeats increased when their treated blood pressures fell below 85, especially if they already had thickened heart muscle from long-time hypertension.

Ordinarily, blood pressure is considered to be elevated when the diastolic pressure - the second, lower blood pressure number - goes above 90. Doctors usually try to get the readings lower, and pressures in the 70s are common among elderly patients on blood-pressure medicines.

However, the study presented Wednesday adds to a growing body of data that questions the wisdom of this strategy.

″It may be that in the elderly, what we consider to be slightly elevated blood pressure is actually optimal,″ said Dr. Brent Egan of the Medical College of Wisconsin.

Egan was senior author of the study, presented at the annual scientific meeting of the American Heart Associaion.

An estimated 63 million Americans have high blood pressure, and the condition is especially common among the elderly. It is an underlying factor in about 32,000 deaths annually.

Whether or not blood pressure is routinely lowered too much is controversial among specialists. Several large studies have found that the death rate falls when blood pressure is brought down to about 85. But below that, it appears to go up again somewhat.

When this information is put on a graph, it forms a J-shaped curve.

″We didn’t expect to find these results,″ said Egan. ″The majority of people in hypertension are not convinced of the J-shaped curve. Our data are consistent with the idea that the curve is real.″

Dr. Peter Sherris of the Kaiser Permanente health maintenance organization in Piedmont, Calif., said ″white-coat hypertension″ - nervousness about doctors that temporarily boosts blood pressure - may be one reason people are overtreated.

He said some of his patients have readings in the office that are 20 or 30 points higher than at home. As a result, he said, ″lots of patients may have blood pressures lower than they need to.″

The latest study was conducted on 80 people with high blood pressure and 55 with normal blood pressure. It found that irregular heart beats were most common among patients who were over age 68, whose readings were below 85 and whose main pumping chambers were enlarged, a muscle thickening called left ventricular hypertrophy.

The abnormal beats were seen in about 50 percent of patients with readings below 85, compared with 10 percent of those with readings of 85 to 94.

″We think that going below 85 is not good for this group,″ said Dr. Hyun Shin, a co-author of the study.

However, Egan cautioned that the work does not prove that readings below 85 are bad for the elderly. While the works ″raises a red flag,″ more studies will be needed to prove that low blood pressure is dangerous for some patients.

″We don’t want to tell all hypertensive patients yet that if their blood pressure goes below 85, they should be worried,″ he said.

Among other blood pressure reports at the meeting Wednesday:

-Dr. Richard Grimm of the University of Minnesota reported benefits of using medicines to treat mild hypertension in younger patients. The study was conducted on 902 men and women ages 45 to 69 who were assigned to make lifestyle changes, including weight loss and exercise, or to take blood pressure lowering medicines as well.

The study found that drugs reduced blood pressure more, and those taking them suffered one-third fewer heart attacks and strokes.

-Dr. James Dwyer and others from the University of Southern California analyzed federal health data on 12,220 people to see if calcium consumption protects against high blood pressure. It found that those who took one gram a day when under age 40 had about a 25 percent reduction in their risk of developing hypertension later.

-Dr. Anthony Spataro and others from the University of Tulsa reviewed 150 studies on 9,880 people to see what effect exercise has on blood pressure. When taken together, the reports suggest that exercise reduces diastolic pressure an average of 6 points.

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