Subtle, Deadly Form of Heart Failure on the Rise
Standard heart-pumping measurements won't pick up 'diastolic' form of the disease
WEDNESDAY, July 19, 2006 (HealthDay News) -- A form of heart failure that's too often overlooked is on the rise among U.S. patients, new research shows, and it's just as deadly as the better-known variety.
The standard description of heart failure is that the heart progressively loses its ability to pump blood. But there's another form of the disease where the heart's blood-pumping ability remains near normal.
In these cases "the heart muscle becomes thickened," explained University of Toronto researcher Dr. Peter P. Liu. "The chamber inside is smaller and the heart is unable to relax to accommodate the blood it needs to pump out. There is no room for the heart to relax, so blood backs up into the lungs."
This kind of aberration isn't picked up by standard measurements of "ejection fraction" -- the percentage of blood in the heart that goes out with every beat.
And two studies published in the July 20 issue of the New England Journal of Medicine suggest that this form of the disease -- called "diastolic heart failure" because the problem occurs during the diastole portion of heart activity, as the heart relaxes after a beat -- may be more common than previously believed.
In its study, Liu's team measured the incidence of diastolic heart failure in more than 2,800 patients admitted to hospitals in the Canadian province of Ontario for two full years. Nearly one-third of those heart-failure patients had an ejection fraction greater than 50 percent, which is very near normal.
However, the death rate for this kind of heart failure matched that of patients with the more common form of heart failure, with more than 20 percent of all the patients dying within a year.
A second study, led by Dr. Margaret M. Redfield of the Mayo Clinic, in Rochester, Minn., found a steady increase over 15 years of heart failure with normal or near-normal ejection fraction.
The proportion of heart-failure cases caused by diastolic heart failure increased from 38 percent in 1987 to 54 percent in 2001 among patients living in the area around the clinic. The study of nearly 4,600 patients found the condition was more common in women than in men.
"One probable cause for the increase is that the population is getting older, and this type occurs more in the elderly," said Redfield, who is director of the Mayo's heart failure clinic. "Also, there is increased recognition of this kind of heart failure."
For patients, the symptoms of both types of heart failure are the same: Shortness of breath, difficulty exercising, and fluid retention in the body. Physicians cannot make a diagnosis on the basis of symptoms or routine examinations, Redfield said. "You have to have an echocardiogram," she said. "You have to see the heart pumping and see if the ejection fraction is normal or reduced."
Until now, relatively little attention has been paid to diastolic heart failure, Liu and Redfield said. "These studies really point out the need to place a lot more effort in understanding this condition," Liu said.
Advances have been made against systolic heart failure, in which the ejection fraction falls below normal, Redfield said, but not much has been done about diastolic heart failure. Her study found that survival improved for systolic, but not diastolic, heart failure over the 15-year period.
"It requires, in a way, that we start over, with more and more studies of this condition," Redfield said.
That effort is beginning, she said, with "a number of studies trying to figure this out." One noteworthy effort is a trial of a new drug treatment for diastolic heart failure sponsored by the U.S. National Institutes of Health, Redfield said.
Find out more about heart failure at the U.S. National Library of Medicine.