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New clue to morning heart risk.

"Grimm death took me without any warning: I was well at night and dead at nine in the morning," reads a tombstone in Sevenoaks, England. Indeed, research indicates that heart attacks and sudden death from cardiac failure strike people most often in the first few hours after they awake.

Since cardiologists first made this observation in the mid-1980s, studies have identified a number of morning-related factors that may contribute to the onset of heart failure. These include increased "stickiness" of blood-clotting cells, called platelets; stress-related rises in blood pressure and heart rate (SN: 6/27/87, p.409); elevated concentrations of heart-stimulating hormones; and increased incidence of silent ischemia, a temporary, often painless reduction of blood flow to the heart (SN: 11/25/89, p.341).

A new study implicates silent ischemia even more strongly than before, says Prakash C. Deedwania of the Veterans Affairs Medical Center in Fresno, Calif. Earlier studies were less definitive because they involved smaller groups, whereas some 1,300 patients at 30 U.S. medical centers participated in the new study, he says.

Participants wore portable heart monitors for two days while they went about their normal activities. The longest and largest number of ischemic episodes occurred between 8 a.m. and 10 a.m., the researchers found.

Deedwania speculates that stress, sticky platelets, hormones, or other, unidentified factors may lead to the higher rates of silent ischemia in the morning. This decreased blood flow, in turn, may damage the heart muscle and increase the chances of unanticipated, possibly fatal heart attacks. "The preponderance of ischemia we are seeing in the morning hours may very well act as a trigger [for heart attacks]," asserts Deedwania, who presented his findings at a meeting of the American College of Cardiology last month in Anaheim, Calif.

Not all experts agree. James E. Muller, codirector of the Institute for Prevention of Cardiovascular Disease at the New England Deaconess Hospital in Boston, calls Deedwania's finding "an important clue to the onset of disease," but he points out that cardiologists are divided about the role of silent ischemia in heart attacks. Muller suggests the phenomenon holds some intermediate position in the "causal chain" that leads to heart failure and sudden death in the morning hours. Ischemia by itself is probably not a direct trigger, he says.
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Title Annotation:silent ischemia linked to heart failure
Publication:Science News
Article Type:Brief Article
Date:Apr 10, 1993
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