US scientists identify risk factors for pediatric hypertrophic cardiomyopathy

US scientists have identified key risk factors that predict which children with hypertrophic cardiomyopathy, the most common cause of sudden death in young people, are at greatest risk of death or need for heart transplant—information that could help physicians figure out who will benefit most from transplant surgery. 

"If we knew who was in the gravest danger from this condition, we could evaluate them for early listing for heart transplant and follow them more closely”, explains study leader Professor Steven E Lipshultz, Director of the Batchelor Children’s Research Institute from the University of Miami Miller School of Medicine in Florida, in The Lancet.

“Now we have identified patient risk factors that can be measured at the time of diagnosis to guide treatment decisions and help newly diagnosed patients and their families have some idea of what to expect from their disease.”

Hypertrophic cardiomyopathy is a serious, potentially fatal, condition that causes the heart muscle to thicken, thus impairing cardiac function and predisposing people to heart failure and sudden death. 

Investigators used the Pediatric Cardiomyopathy Registry (PCMR), a database of paediatric cardiomyopathy patients from 98 centres across the USA and Canada diagnosed over a 19-year period. They analysed the clinical and demographic characteristics at the time of diagnosis of 1085 children (18 years of age or younger) and their contribution to the outcomes of death and heart transplantation. 

The study, funded by the National Heart, Lung, and Blood Institute and the Children's Cardiomyopathy Foundation, found that children with inherited metabolic diseases or with hypertrophic cardiomyopathy in combination with other cardiomyopathy phenotypes had a worse prognosis. Younger age, lower weight, presence of congestive heart failure, and echocardiographic evidence of abnormal left ventricle structure or function were also important risk factors for death or transplantation.

Importantly, for all forms of hypertrophic cardiomyopathy, the risk of death or heart transplant was significantly increased when two or more of these risk factors were present at diagnosis.

According to Lipshultz, “Not only is the absolute risk of death or heart transplantation significantly higher when multiple risk factors are present, but the risk increases significantly as the number of risk factors increases.”

Writing in a linked Comment, Robert G Weintraub from the Royal Children’s Hospital, Melbourne, Australia, and Christopher Semsarian from the Royal Prince Alfred Hospital, Sydney, Australia say, “These data should allow early risk stratification and close monitoring, enabling timely and appropriate listing for heart transplantation. Identification of long-term outcomes for young patients with hypertrophic cardiomyopathy, including rates of sudden death and the effect of frequently used interventions, should be a focus for future investigation.”

The study will be presented at the European Respiratory Society (ERS) Annual Congress 2013.