The Natural History and Clinical Course of Hypertrophic Cardiomyopathy

Today hypertrophic cardiomyopathy (HCM) can be easily diagnosed from birth to the 8th decade by two-dimensional echocardiography (2D-echo). Abnormal wall thickness of the left and right ventricle can be detected and measured in vivo. A reliable diagnosis of both typical (Fig. 1) and atypical (Fig. 2) patterns of HCM can be made [1], although some pitfalls may be encountered. In the majority of the patients with HCM, hypertrophy is present in the interventricular septum and the anterolateral wall of the left ventricle (LV). Less frequently it can be localized in one or more segments, namely the posterior interventricular septum, the posterior or lateral wall, at the apex, or at midventricular level [2]. Apical HCM may involve only the apical portion of the LV, or be diffuse when additional walls are hypertrophied. A minimal thickness of at least 15 mm (and 17 mm in the lateral wall and posterior septum) and a septal to posterior free wall ratio of 1.5 is required for the diagnosis of HCM in adult patients in the absence of other factors which can cause hypertrophy. Symmetric LV hypertrophy is rare [3].