Genetics of pediatric heart failure

Heart failure, in the absence of underlying metabolic or structural defects, remains a multifactorial disorder whose pathogenesis and progression are attributable to both genes and environment. Inherited and acquired risk factors impact cardiac structure and function throughout prenatal and postnatal development, yet cardiovascular decompensation and onset of clinical heart failure in ischemic or idiopathic myocardial disease are often delayed until adulthood. Recognition of pathogenic mechanisms and identification of risk factors for coronary artery disease have focused public health policy on preventative measures, beginning in childhood. In heart failure due to primary myocardial disease, by contrast, limited understanding of etiology and years of presymptomatic but progressive cardiac dysfunction have hampered early diagnosis, effective treatment, and prevention. Similarly, when cardiomyopathic heart failure occurs in children, typically in the first year of life, the etiology is usually idiopathic and traditional medical therapy has not appeared to alter the natural history (1,2). Indeed, advanced myocardial disease with substantial remodeling is often present in adults who present with symptomatic congestive cardiomyopathy, and the 5-year mortality rate was 20-60% in an era when beta-adrenergic receptor blockers were investigational drugs (3). Outcome in the current era is no different in children, nearly 40% of who die or require cardiac transplantation (2). The prognosis in individual patients, nevertheless, is often unpredictable, ranging from intractable heart failure to occasional spontaneous recovery (4,5). Idiopathic dilated cardiomyopathy is the most common basis for cardiomyopathy in children (2,6,7), for congestive heart failure in adult referral populations (8), and for cardiac transplantation, despite a much higher prevalence of coronary artery disease (5).