Fighting the Silent Attacker

By Joe Levine.

The first clue is often the catastrophe itself: a fatal heart attack. But the events that set the stage for disaster, like those preceding an earthquake, have been occurring for years beneath the surface, painless and unnoticed. The culprit is silent ischemia, an intermittent interruption of blood flow to the heart, which kills tens of thousands of seemingly healthy Americans each year. Doctors estimate that the condition, undetected, exists in an additional 3 million to 4 million people known to have heart disease and further increases the likelihood they will suffer a heart attack.

Although silent ischemia was identified nearly two decades ago, the attention it received at last week's annual scientific meeting of the American Heart Association in Dallas reflected a growing awareness that it is a formidable medical problem. Says Cardiologist William Shell, of the University of California, Los Angeles: "It may be silent, but it can be deadly."

One study presented in Dallas by researchers from the Johns Hopkins Medical Institutions appears to bear him out. The Hopkins team, led by Cardiologist Sidney Gottlieb, examined 103 heartattack patients who seemed to be recovering without complications or pain and found that 30 were having ischemic episodes. One year later nine (30%) of these people had died from heart attacks. Of the 73 without silent ischemia, only eight (11%) had suffered fatal heart attacks. "If you have had a heart attack and you have ischemia," Gottlieb concluded, "you may have a three times greater risk of dying."

Ischemia occurs when coronary arteries partly clogged with fatty deposits of plaque suddenly contract in spasms or are blocked by a clot, depriving the heart muscle of blood and thus oxygen. While painful or "noisy" ischemia (angina) often results from physical stress, like climbing stairs, even slight exertions, like balancing a checkbook, can trigger silent ischemia. During these episodes, which typically last a few minutes but can go on for ten hours, large portions of heart muscle can be damaged. Yet in more than 75% of all cases, for still unknown reasons, the victim feels no pain.

Then how is silent ischemia diagnosed? Doctors can detect attacks by monitoring electrical signals from their patients' hearts during exercise stress tests; a sudden decrease in blood flow to the muscle changes the signal. The condition can then be confirmed by a Holter monitor, a portable electrocardiograph worn by the patient for at least 24 hours.

But many doctors will not yet order the test. "There is still a school of thought that believes, 'No pain, no worry,' " says Peter Cohn, chief of cardiology at the State University of New York's Health Sciences Center at Stony Brook. He recommends annual testing only for people who are at risk because of diabetes, smoking, high cholesterol, high blood pressure or a family history of heart disease. Healthy people not at risk probably should not be concerned, he says. Men at risk should begin testing between the ages of 35 and 40; women, at 45.

Some doctors, after diagnosing ischemia, prescribe nitroglycerin, calcium blockers and other drugs that relax constricted arteries or slow the heart rate. Shell favors nitroglycerin patches applied to his patients' skin. "We don't have proof that this lowers the risk of heart attack," he says, "but anecdotally, I can tell you that my patients are doing better." Others have used bypass surgery (which allows blood to circumvent clogged arteries) or balloon angioplasty (to widen arterial passageways) against the silent attacks.

Doctors at the conference stressed that detecting silent ischemia will not merely prevent a few thousand dramatic deaths. It will also uncover heart disease in many people who are unaware that they have it. The stress and Holter tests are costly (about $200 each), according to Dr. Carl Pepine, a silent-ischemia expert from the University of Florida at Gainesville, but no more so than the toll ultimately taken by heart disease itself. Says he: "We're talking about the one disease that kills the most people in the country, many in middle age, when they are making their greatest contribution to society. That's expensive too."

Having children can sometimes be a trial. But a study revealed at the Dallas meeting last week by Epidemiologist Evelyn Talbott suggests that not having offspring can lead to far more serious consequences. Childless women over 50, she reported, may be at greater risk for sudden, fatal heart attacks than their contemporaries who are mothers.

Talbott's team at the University of Pittsburgh found that of 51 Allegheny County, Pa., female heart-attack victims over 50, twelve had never given birth. In contrast, only two of 47 healthy women over 50 and from the same neighborhood were not biological mothers. In women 50 or younger, childlessness appeared to be unrelated to the risk of sudden death.

Were the heart-attack deaths of the childless older women triggered in part by psychological pressures, such as loneliness and regret over not having had children? Talbott leans toward a more biological explanation. In these women, she says, abnormal levels of female hormones may have played a role. She concedes that for now the study "raises more questions than it answers."

With reporting by Christine Gorman/Dallas