A study of almost 5,000 older adults living in four U.S. communities showed that more than half of those with heart failure had a little-understood form of the disorder that doctors know little about treating, report researchers in this week''s American Journal of Cardiology.
"Our study suggests that a large proportion of older adults with heart failure have a recently recognized, little-understood form of the disorder, and that it''s especially common among women," said Dalane W. Kitzman, M.D., associate professor of cardiology at Wake Forest University Baptist Medical Center (WFUBMC) and the study''s main author. "The implications to public health are enormous."
Doctors previously believed that most heart failure was a weakening of the heart muscle that kept it from pumping enough blood (systolic heart failure). In recent years, however, a second form has been recognized: the heart can empty normally, but the main pumping chamber doesn''t fill with enough blood (diastolic heart failure). The result is the same - the body does not get enough oxygen-rich blood for its needs. The most common symptom is shortness of breath.
This was the first large, community-based study of heart failure among older adults. It was conducted by researchers from WFUBMC as well as the University of California at Irvine, St. Francis Hospital in Roslyn, New York, the University of Washington at Seattle, the University of Massachusetts Medical Center, the University of Vermont in Burlington and the University of Arizona at Tuscon.
"For years, we focused on systolic heart failure as though it was the only kind that existed," said Kitzman. "Now, through our study and others, we''re realizing that diastolic failure may be the more common form among older adults, especially women."
The researchers studied 4,842 participants who were 66 and older. Of those, 425 (8.8 percent) had a confirmed history of congestive heart failure. To determine each person''s type of heart failure, ultrasound technology was used to measure the percentage of blood the heart emptied with each beat. A normal heart can pump 50 percent or more of its volume with each beat.
The study found that more than half (55 percent) of participants with congestive heart failure had normal emptying and could be diagnosed with diastolic dysfunction - the second type of heart failure. Among women with heart failure, 67 percent had diastolic failure, compared to 42 percent of men.
"The majority of older adults did not have the type of heart failure that has been well-researched for the past 30 years," said Kitzman. "Instead, they had a type that we don''t fully understand its cause, how it progresses or how to best treat it. The implications are enormous considering that heart failure is the number one cause of hospitalization for people age 65 and older in the United States."
The research was part of the large multi-center Cardiovascular Health Study of cardiovascular disease risk in the elderly. Sponsored by the National Heart, Lung and Blood Institute, the study followed residents in four communities (Forsyth County, N.C., Sacramento County, Calif., Allegheny County, Penn., and Washington County, Md.) for 10 years.
In the United States, about 5 million people have heart failure and an additional 550,000 are diagnosed with it annually. It is one of the largest health problems in the developed world. The standard treatments for systolic heart failure include water pills, blood thinners and medications that cause the blood vessels to widen or increase the force of the heart''s contractions.
Researchers are currently evaluating the best treatments for diastolic heart failure. WFUBMC is conducting five studies to evaluate several drugs (angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers) and exercise as treatments for the disorder.
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