Long-term outcome of 4 Korean families with hypertrophic cardiomyopathy caused by 4 different mutations

Background: We sought to describe the long-term outcome of individuals in 4 Korean families with hypertrophic cardiomyopathy (HCM) with known mutations. Hypothesis: Long-term clinical features of familial HCM might be characterized according to the mutation causing HCM. Methods: We performed long-term (mean, 13.1 y) clinical evaluations on 46 subjects from 4 Korean families with different mutations. Results: Myosin light chain 3 gene (MYL3) mutation was associated with late-onset HCM with relatively poor prognosis; 1 sudden cardiac death and 2 cases of heart failure with atrial fibrillation occurred among 12 subjects with this mutation. Myosin binding protein C gene (MYBPC3) mutation was associated with 2 cases of sudden cardiac death and 3 cases of heart failure among 7 affected members. Cardiac troponin I type 3 gene (TNNI3) mutation was associated with 5 deaths related to atrial fibrillation and stroke among 12 mutation-positive members. Myosin heavy chain 7 gene (MYH7) mutation was associated with 11 deaths in 15 affected members. Conclusions: The clinical course was quite different for different HCM mutations. Even within the same family, individuals carrying the same mutation differed in disease expression and prognosis.