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The newspaper of The Johns Hopkins University November 13, 2006 | Vol. 36 No. 11
Pacemakers — Not Beta Blockers — May Be Best for Some Heart Patients

By David March
Johns Hopkins Medicine

Evidence now exists, researchers at Johns Hopkins report, to support a dramatic change in the way hundreds of thousands of Americans with a form of heart failure should be treated.

In a follow-up to previous work, Hopkins cardiologists say that patients with nonsystolic heart failure may benefit more from pacemakers to speed up the heartbeat rather than from continual long-term use of beta blockers, drugs that slow down the heartbeat.

It is estimated that almost half the 550,000 Americans newly diagnosed each year with heart failure have the nonsystolic form.

"Cardiologists are constantly being forced to rethink heart failure because one size does not fit all," said senior study investigator David Kass, the Abraham and Virginia Weiss Professor of Cardiology at the School of Medicine and its Heart Institute. "We really have to be careful about how we diagnose and approach its treatment.

"We also need to understand all facets and manifestations of the disease because we are seeing ever-increasing numbers of older adults who have heart failure, mostly women over age 50, whose heart pumping appears to be normal. And their cases are clearly different from traditional, systolic heart failure, where pumping function is depressed. However, almost all of the research over the last three decades has applied only to those with systolic heart failure," Kass said.

Nonsystolic heart failure is characterized by fairly normal function of the heart's pumping action, or so-called ejection fraction, when a person is at rest. This action falters, however, once daily physical activity begins and the heart becomes increasingly unable to squeeze out sufficient blood flow to energy-starved muscles. Even small tasks, such as getting dressed in the morning, can leave people exhausted and short of breath. Until now, Kass noted, researchers had thought the problem was that these hearts could simply not relax properly, a so-called failure of their diastolic function.

The Hopkins team plans to launch within the next year a national study of the use of pacemakers in patients with this form of the disorder, which is sometimes referred to as heart failure with preserved ejection fraction or as heart failure with normal ejection fraction.

In some cases, a combination of drug and device may work best to control the disease, speeding up the heartbeat at times, slowing it down at other times.

The latest report from the Johns Hopkins team, published in the journal Circulation online Nov. 6, follows presentation of its initial findings at last year's Scientific Sessions of the American Heart Association.

People with the more common, systolic form of the disease have a pumping function that is evenly depressed and weakened at all times, not just with exercise or activity. Beta blockers have been proven widely effective in minimizing the stresses placed on the failing heart during physical activity, when the body needs to more quickly squeeze out blood to the rest of the body.

The Johns Hopkins study is believed to be one of the first to do a head-to-head comparison of those with nonsystolic heart failure and patients with similar medical histories — including high blood pressure, a relatively high ejection fraction and overgrown hearts — but no major symptoms of heart failure. The group studied was relatively small, Kass said, and involved mostly African-Americans from the Baltimore region. Nineteen older men and women with initial symptoms of nonsystolic heart failure were compared to 17 patients with no early signs of the disease. African-Americans are at particular risk for this kind of nonsystolic heart failure.

When all pedaled at increasing levels on a stationary bike, their hearts filled with blood in a similar way. However, heart function quickly differed in two key measures that explained why those with nonsystolic heart failure could not exercise.

Hearts of participants in the nonsystolic group failed to keep up, beating on average 44 percent less quickly during exercise than those of participants without heart failure. Also during exercise, blood vessels in the heart failure group did not dilate or expand as much to meet the increased energy demands from the body's muscles. The corresponding resistance to blood flow dropped 28 percent in controls as blood vessels relaxed but dropped only 19 percent in the heart failure group.

In their planned study next year, the Johns Hopkins scientists will monitor more than 80 men and women with mild to moderate nonsystolic heart failure. Half will be taking traditional beta blocker medications, the most commonly prescribed treatment, while the rest will not. All will be implanted with a pacemaker and perform exercise tests to see if their symptoms get better — or are possibly even reversed.

If the new study validates the preliminary work, Kass predicts that his research could change the practice guidelines about how beta blockers and pacemakers are used in this form of heart failure.

The American Heart Association estimates that more than 5 million Americans have some form of congestive heart failure, marked by symptoms such as shortness of breath and fatigue.

Funding for the reported study was provided by the National Institutes of Health and the Peter Belfer Laboratory Foundation. Other researchers were Barry Borlaug (lead), Vojtech Melenovsky, Laura Shively, Kristy Swigert and Lewis Becker.


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