We performed a systematic literature review of recommended 'major' and 
'possible' clinical risk markers for sudden cardiac death (SCD) in hypertrophic 
cardiomyopathy (HCM). We searched the Medline, Embase and Cochrane databases for 
articles published between 1971 and 2007. We included English language reports 
on HCM patients containing follow-up data on the endpoint (sudden) cardiac death 
using survival analysis. Analysis was undertaken using the quality of reporting 
of meta-analyses (QUORUM) statement checklist. The quality was checked using a 
quality assessment form from the Cochrane Collaboration. Thirty studies met 
inclusion criteria and passed quality assessment. The use of the six major risk 
factors (previous cardiac arrest or sustained ventricular tachycardia, 
non-sustained ventricular tachycardia, extreme left ventricular hypertrophy, 
unexplained syncope, abnormal blood pressure response, and family history of 
sudden death) in risk stratification for SCD as recommended by international 
guidelines was supported by the literature. In addition, left ventricular 
outflow tract obstruction seems associated with a higher risk of SCD. Our 
systematic review provides sound evidence for the use of the six major risk 
factors for SCD in the risk stratification of HCM patients. Left ventricular 
outflow tract obstruction could be included in the overall risk profile of 
patients with a marked left ventricular outflow gradient under basal conditions.