Risk stratification of sudden cardiac death in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common hereditary cardiac condition and the leading cause of sudden cardiac death (SCD) in young adults. Given that SCD can be the first and most devastating clinical expression of HCM, identifying individuals at high risk is paramount. Determining an individual's risk for HCM-related SCD requires a thorough understanding of the recognized risk factors, of which there are seven established or 'major' and five 'possible'. Major risk factors can be identified by thoroughly reviewing a patient's personal medical history and noninvasive cardiovascular testing. The presence of major risk factors identify patients who are at high enough risk of SCD to warrant consideration of an implantable cardioverter-defibrillator; whereas the absence of any major risk factors provides considerable reassurance to both patient and physician. The risk of HCM-related SCD in patients with no major risk factors is, however, not zero. Possible risk factors gain importance in the presence of an isolated major risk factor. Here, we provide a contemporary review of established and possible risk factors for HCM-related SCD. We also examine microvolt T-wave alternans and cardiovascular MRI as emerging risk stratification tools that could further hone our ability to accurately identify the high-risk patient.