Study unveils mystery of dilated cardiomyopathy
By Ross Tomlin
The mystery behind a commonly untreatable and undetected heart muscle disease in children is partially revealed for the first time in a recent report in the Journal of the American Medical Association.
In a multi-center, international study called the Pediatric Cardiomyopathy Registry, researchers at Baylor College of Medicine and Texas Children's Hospital in Houston along with colleagues from Harvard Medical School, the University of Miami and others, showed that the underlying causes, frequencies, and outcomes of dilated cardiomyopathy, which often leads to heart failure, parallel those in adults with the same disorder.
In addition, the researchers found that dilated cardiomyopathy is more common among boys of all races and in blacks compared to whites.
What is dilated cardiomyopathy?
Dilated cardiomyopathy is the most common form of cardiomyopathy at any age. Cardiomyopathy refers to dysfunction of the heart muscle. Dilated cardiomyopathy occurs when the left ventricle, the heart's major pumping chamber, becomes enlarged and cannot pump effectively. This can cause heart failure and, in some cases, heart arrhythmia or a misfiring of the pumping of the heart. In some cases, this can lead to the need for a heart transplant.
"Children with dilated cardiomyopathy are at the same level of risk as adults of having sudden cardiac death and needing transplants," said senior author Jeffrey Towbin, M.D., professor of pediatrics at BCM and chief of pediatric cardiology at TCH. "It is a major cause of death in children just like it is in adults."
Funded by the National Heart, Lung, and Blood Institute, the study identified the causes in 35 percent of the over 1,400 cases of pediatric dilated cardiomyopathy studied. The most common cause was myocarditis (inflammation of the heart). The origins of roughly two-thirds of cases studied were unknown. Infants (less than one year old) were almost 10 times more likely to develop the disorder than any other pediatric age group (up to 18 years old) studied.
Survival the same in children and adults
Survival rates for children with dilated cardiomyopathy were also found to be approximately the same as in adults with the condition. In both groups, around 70 percent live beyond the first year of the disorder's onset, and only 50 percent survive past five years.
Approximately one-third to one-half of all cases of dilated cardiomyopathy have a genetic or inherited basis, and for this reason Towbin recommends that people with a family history of the disorder be tested for it.
"Even though we can't always determine what the cause is, we may be able to determine if it's inherited based on family history and non-invasive testing of family members such as with echocardiograms (ultrasound of the heart) and EKGs," Towbin said. "With an early diagnosis, we can begin therapy and assess whether transplantation could be necessary in the near-term or future."
Although these findings represent a major stride toward better understanding and treating dilated cardiomyopathy, Towbin says much work remains.
"Despite advances in diagnosis and treatment, we are still having significant problems with outcomes in these children just like we are in adults," said Towbin. "There needs to be more support for research in this area."
The TCH-BCM pediatric cardiology program is the largest cardiomyopathy and heart failure program for children in North America.
The paper's other authors include Steven Lipshultz, M.D., of the University of Miami; Steven Colan, M.D., of Harvard Medical School and Children's Hospital Boston; and Lynn Sleeper, M.D., of New England Research Institutes; and others.
The article can be found at http://jama.ama-assn.org/cgi/content/full/296/15/1867?maxtoshow=&HITS=10&hits=10&RESULTFORMAT= &fulltext=towbin%2C+ja&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT.
