Risk factors and stratification for sudden cardiac death in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a primary cardiac disease characterised by a diverse clinical expression'-6 in which prema- ture sudden unexpected death has been regarded as a critical feature of its natural his- tory.'-23 However, it is also apparent that not all patients within the disease spectrum are at equal risk of premature death, and indeed in some individuals the disease seems to convey little or no risk.'7-'9 24 25 Consequently, intense investigative interest and substantial energy have been directed toward the identification of "risk factors"that is, those features of the disease that are perceived to predispose specific patients with HCM to sudden death or cardiac arrest.7 8 12 14 16-19 26-31 Nevertheless, despite these exploratory studies in risk stratification, there are few comprehensive and prospec- tively obtained long-term data analysed in a multivariate fashion. Though knowledge is rapidly evolving and workable approaches are beginning to emerge, the definition of precise approaches for most patients and clinical situ- ations remains incomplete. Indeed, because such controversy persists regarding the definition of risk it seems justified and timely to review the available data to summarise what is known about the risk of sudden death in HCM. We hope to show that prospective trials are needed and to evolve a practical approach and workable guidelines to aid the develop- ment of diagnostic and therapeutic strategies.