Abstract
We present two cases of biopsy-proven hypertrophic cardiomyopathy (HCM). Both cases showed abnormal electrocardiographic (ECG) findings more than 8 years before diagnosis. A 16-year-old healthy male experienced a rescued cardiac arrest. Another male adolescent showed abnormal Q wave and thickened ventricular wall at 15 years old. Retrospective analyses of ECGs performed at 6 years old indicated abnormal ECG findings. However, the diagnosis was normal because no ventricular wall thickening was present in echocardiography. For early diagnosis of HCM to prevent sudden cardiac arrest or death, it is essential to establish ECG and echocardiographic criteria to screen HCM in the young.