"Even though the recently recognized form, called diastolic heart failure, is less deadly in individuals, it produces more deaths nationwide because of its much higher prevalence," said Dalane W. Kitzman, M.D., a cardiologist from Wake Forest University Baptist Medical Center. "In our study of older adults with heart failure, over twice as many participants had diastolic heart failure, suggesting that a key to reducing heart failure deaths is successful treatment of this second type."
Also participating in the research were: St. Francis Hospital, Roslyn, N.Y.; the Mayo Clinic, Rochester, Minn.; the University of Washington in Seattle; the University of Vermont in Burlington; Tufts-New England Medical Center, Boston, Mass.; St. Johns Hospital and Medical Center, Detroit, Mich.; and the University of Massachusetts at Worcester. The research was funded by the National Heart, Lung, and Blood Institute.
The researchers examined data from the Cardiovascular Health Study, which assessed cardiovascular disease in more than 5,000 adults over age 65 living in four United States communities: Forsyth County, N.C.; Sacramento County, Calif.; Pittsburgh, Penn.; and Washington County, Md. The goal of the analysis was to learn whether the type of heart failure affects mortality.
With the most widely known type of congestive heart failure - systolic heart failure - the heart doesn't contract strongly enough. With the newly recognized type - diastolic heart failure - the heart's main chamber doesn't fill with enough blood. The end result in both types is that the body doesn't get enough oxygenated blood to meet its demands.
The current analysis was the largest population-based study to date to evaluate hospitalization and death rates in older adults with heart failure. Previous studies have shown five-year mortality rates as high as 75 percent for people diagnosed with congestive heart failure.
The CHS used ultrasound images of the heart along with participants' physical symptoms to diagnose heart failure type. The researchers compared outcomes in four groups of participants: no heart failure, diastolic heart failure, systolic heart failure, and no symptoms of heart failure but with weakened heart contraction that usually precedes systolic heart failure.
In the group with no heart failure, the mortality rate was 2.5 percent a year. The mortality rate was more than three times higher for those with diastolic heart failure (8.7%) and those with early signs of systolic heart failure (8.9%). The mortality rate was highest (15.4%) in the group with systolic heart failure. However, because there were more than twice as many persons with diastolic heart failure than with systolic heart failure, more deaths were associated with this newer form than with systolic heart failure.
Kitzman said the research is important because many doctors had believed that diastolic heart failure is not as serious as systolic failure.
"People have thought these patients don't have high mortality," said Kitzman. "But this research shows that there is significant mortality among elderly people with congestive heart failure - regardless of which type they have. This is a significant public health problem that we need to learn more about treating."
Congestive heart failure is the most frequent cause of hospitalization in people age 65 and older and accounts for more than 875,000 hospital admissions each year in the United States.
The standard treatments for systolic heart failure, the more widely known form of heart failure, include water pills and medications to expand the blood vessels or increase the force of the heart's contractions. Most treatments were studied in male populations younger than 65 with systolic failure. However, about 88 percent of heart failure cases occur in the elderly and the majority have diastolic heart failure. Furthermore, the majority of diastolic heart failure patients are women.
"The results of those clinical trials may not be applicable to the elderly and to others with diastolic heart failure," said Kitzman. Researchers at Wake Forest are currently conducting several research studies on the most effective treatments for diastolic heart failure, including exercise and investigational drugs.