Hypertrophic cardiomyopathy

PURPOSE OF REVIEW: Hypertrophic cardiomyopathy (HCM) is the second most common childhood heart muscle disease and is the most common cause of unexpected sudden cardiac death in young people. The purpose of this review is to describe the risk of sudden death, to assess which of the criteria conventionally used as indication for a primary prevention defibrillator placement in adults are applicable in children with HCM, and to review differences in management between Europe and North America. RECENT FINDINGS: There is no uniform 'annual mortality rate' in childhood, and the risk of sudden death is at its highest level between 8 and 16 years. There are no significant differences between sudden death fatality rates in childhood HCM in Europe, North America and Australia when patients presenting with sudden death as the first sign of disease are excluded. The criteria for primary prevention defibrillator placement in adults with HCM are, with the exception of previous cardiac arrest and ventricular tachycardia on Holter monitoring, not predictive of risk in childhood HCM, and further research is required to establish better criteria for primary prevention in children. SUMMARY: Most children diagnosed with HCM have a favorable prognosis with life-style modification with additional medical therapy, surgical therapy, and/or defibrillator placement in selected patients. The challenges inherent in identification of the patients most likely to benefit from invasive therapies and avoidance of these therapies in those least likely to benefit (and most likely to experience harm) exist on both sides of the Atlantic.