In patients with hypertrophic cardiomyopathy, left ventricular outflow tract obstruction at rest is a strong, independent predictor of progression to severe symptoms of heart failure and of death.

HE RISK OF SUDDEN DEATH IN PA-tients with hypertrophic cardiomyopathy (HCM) has been known for almost 50 years. [1][2][3][4][5][6] Indeed, this disease is the most common cause of sudden cardiac death in young people, 1-6 including trained athletes. 7 However, only in the last few years has the implantable cardioverterdefibrillator (ICD) been systematically used as a potentially life-saving For editorial comment see p 452.

Ventricular tachycardia or fibrillation appears to be the principal mechanism of sudden death in patients with hypertrophic cardiomyopathy. In high-risk patients with hypertrophic cardiomyopathy, implantable defibrillators are highly effective in terminating such arrhythmias, indicating that these devices have a role in the primary and secondary prevention of sudden death.

Surgical myectomy performed to relieve outflow obstruction and severe symptoms in HCM was associated with long-term survival equivalent to that of the general population, and superior to obstructive HCM without operation. In this retrospective study, septal myectomy seems to reduce mortality risk in severely symptomatic patients with obstructive HCM.

Our data suggest that cardiac remodeling associated with HCM determines a significant release of miRNAs into the bloodstream: the circulating levels of both cardiac- and non-cardiac-specific miRNAs are significantly increased in the plasma of HCM patients. However, correlation with left ventricular hypertrophy parameters holds true for only a few miRNAs (i.e., miR-199a-5p, -27a, and -29a), whereas only miR-29a is significantly associated with both hypertrophy and fibrosis, identifying it as a potential biomarker for myocardial remodeling assessment in HCM.