
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: WEDNESDAY, March 21, 1990                   TAG: 9003232626
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A/8   EDITION: EVENING 
SOURCE: Associated Press
DATELINE: NEW ORLEANS                                 LENGTH: Medium

SLOW RISE IN HEART RATE MAY TRIGGER PAINLESS ANGINA

Long periods of moderate stress common in daily life can trigger potentially hazardous disruptions in the heart's blood supply, a new study shows.

The research is the latest effort to understand what happens during silent ischemia - painless moments when the heart needs more blood than its arteries can supply.

As many as 3 million to 4 million Americans have these episodes without knowing it. Heart specialists are debating just what to do about them, and even whether the spells are truly dangerous.

At a meeting Tuesday of the American College of Cardiologists, a Boston team presented evidence that the heart rate may gradually increase for a half-hour before the heart becomes ischemic, or deprived of oxygen-carrying blood.

Heart rates of 21 people were monitored by portable recording devices as they went about their daily routine. Even at their most rapid, their hearts often did not beat remarkably fast.

"It is not necessarily how strongly you turn on your cardiovascular system. It's how long," said Dr. Andrew Selwyn, the study's senior author from Brigham and Women's Hospital.

In the study, silent ischemia occurred when the subjects' heart rates rose from an average of 74 to 95 beats per minute. But three-quarters of this increase took place over periods up to a half-hour before the ischemia.

When ischemia causes pain, it is known as angina. People can take a variety of drugs to ease this condition. Some experts believe that silent ischemia is just as hazardous as the painful variety and give their patients the same medicines.

The Boston study suggests such medication may not have the same effect on all kinds of silent ischemia. It found that drugs called beta blockers worked well controlling ischemia that occurred during moderate and high heart rates, but nitrates worked best at low rates.

The idea that silent ischemia should be identified and treated is based in part on studies showing that people with this condition are especially prone to heart attacks and deaths. But some question whether this is true for the majority of essentially healthy people with silent ischemia.

He presented data based on 20 months of follow-up research on 81 patients with mostly mild heart disease. Those with silent ischemia did just as well as people with no signs of blood shortage to their hearts.

by CNB