This study demonstrates that LVNC is associated with a better prognosis than previously reported. In patients with familial disease, relatives may have features consistent with dilated cardiomyopathy rather than LVNC.

LVOTO is associated with an increased risk of SD/ICD that is related to the severity of obstruction and the presence of other recognized risk factors for SD. The low sudden death mortality in asymptomatic patients with LVOTO and no other SD risk markers suggests that aggressive interventions to reduce LVOTO are unwarranted in this group. Further studies are required to determine the most appropriate treatment strategies (ICD or gradient reduction) in patients with additional risk factors.

Black ethnicity is an important determinant of the phenotypic expression of HCM but does not adversely affect outcomes. Apical and concentric hypertrophy are common in black patients and may hinder the identification of HCM in this cohort. Hypertension has an adverse effect on outcome, irrespective of ethnicity.