Underlying causes, frequencies, and outcomes of dilated cardiomyopathy

The mystery behind a commonly untreatable and undetected heart muscle disease in children is partially revealed for the first time in today's edition of the scientific journal JAMA.

In a multi-center, international study, researchers at Baylor College of Medicine (BCM) and Texas Children's Hospital (TCH) in Houston showed the underlying causes, frequencies, and outcomes of dilated cardiomyopathy (DCM), which often leads to heart failure, paralleling those in adults with DCM. The study also found DCM to be more common among boys of all races and in blacks compared to whites.

"Children with dilated cardiomyopathy are at the same level of risk as adults of having sudden cardiac death and needing transplants," said senior author Dr. Jeffrey Towbin, 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, one of the National Institutes of Health, the study identified the causes in 35 percent of the 1,400 cases of pediatric DCM studied, the most common one being myocarditis (inflammation of the heart). The origins of the roughly two-thirds of cases studied were unknown. Infants (less than one year old) were almost ten times more likely to develop DCM than any other pediatric age group (up to 18 years old) studied.

Survival rates for children with DCM 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.

DCM, the most common form of cardiomyopathy at any age, occurs when the left ventricle, the heart's major pumping chamber, becomes enlarged and cannot pump effectively, usually resulting in heart arrhythmia, heart failure, and the possible need for a heart transplant. Other forms of cardiomyopathy are characterized by the heart's inability to relax appropriately between pumps, and their outcomes are commonly sudden, unexpected cardiac death.

Roughly one-third of all cases of DCM are genetic in origin. Towbin recommends that people with a family history of DCM be tested for the disorder.

"Even though we can't always determine what the cause is, we know if it's inherited," Towbin said. "With an early diagnosis, we can begin therapy and assess whether transplantation is necessary."

Although these findings represent a major stride toward better understanding and treating DCM, 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."

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