High risk for sudden death identified by electrocardiographic loop recording in a patient with hypertrophic cardiomyopathy without major risk factors.

Recurrent presyncope is occasionally reported by patients with hypertrophic cardiomyopathy (HC). However, it is difficult to identify on 24-hour Holter recordings the mechanisms responsible for these infrequent symptoms. We report the case of a patient with HC with recurrent presyncope and without major sudden death risk factors, in whom electrocardiographic loop recording identified life-threatening arrhythmias as the mechanism responsible for these symptoms. Documentation of these arrhythmias justified implantation of a cardioverter-defibrillator in the absence of other risk factors.