Congestive heart failure, a condition that affects more than 3 million Americans, can involve problems in the heart's pumping ability as well as its ability to relax and fill with blood between beats. The latter aspect, called diastolic functioning, has been understudied, some experts say.
But a Mayo Clinic survey of 2,042 residents of Olmsted County in Minnesota suggests that abnormal diastolic functioning may be more dangerous than previously thought. In the survey, more than one in four adults older than 45 were found to have these abnormalities in diastolic functioning that can boost their death risk. And they were eight times more likely to die within the five-year follow-up than those who had normal functioning.
"If you have a problem with diastolic functioning, even if you don't have [diagnosed] heart failure at that time, that abnormality was associated [in the study] with increased mortality from all causes," explains Dr. Margaret Redfield, director of the Mayo Clinic Heart Failure Clinic and lead author of the study, appearing in tomorrow's Journal of the American Medical Association.
Redfield hopes the study will raise awareness among other cardiologists, internists and family physicians as well as consumers about the causes of heart failure. Problems not only with heart-pumping function but also the heart's ability to relax and fill with blood can increase the risk of heart failure and death, she says.
To consumers, she adds, "Be aware that heart failure can be caused by a normally squeezing but stiff heart." In other words, your heart is pumping properly but not properly filling with blood between beats.
Symptoms of heart failure include shortness of breath, easy tiring, fatigue, and swelling of the feet, ankles and legs as fluid accumulates. Several drugs treat the condition.
"We knew diastolic problems could cause heart failure," Redfield says. "But we were somewhat surprised by how potent a predictor of mortality the presence of diastolic dysfunction was."
More than a fourth of those studied had diastolic abnormalities and often had not been diagnosed yet with heart failure.
Redfield says she is hopeful the study result will encourage more consistent measurements of the diastolic functioning of the heart, which are done through an echocardiogram, a recoding of sound waves bounced off the heart to produce images of it.
She also hopes that general-practice physicians and internists will become more aware of the potential problems those with diastolic dysfunction could have.
The study is "very important," says Dr. Zi-Jian Xu, a cardiologist at the UCLA-Santa Monica Cardiology Group in California, "because the problem is very prevalent."
"Physicians for years have observed the phenomenon [of diastolic problems]," he says. "But not one has put numbers to it. It's been known that diastolic dysfunction is one of the causes of morbidity [disease], and now it's linked to mortality."
To consumers, Redfield gives this advice: "If you have symptoms [of heart failure] and your doctor says your heart is squeezing just fine, your next question should be, 'Is its relaxing-and-filling function normal?'"
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