Relation between extent of cardiac muscle cell disorganization and left ventricular wall thickness in hypertrophic cardiomyopathy.

The presence of numerous, abnormally arranged, cardiac muscle cells distributed widely throughout the hypertrophied left ventricular (LV) wall has been considered a characteristic, morphologic feature of patients dying of hypertrophic cardiomyopathy (HC) and also probably a determinant of impaired LV compliance. However, the relation between such regions of myocardial cell disarray and the magnitude of wall thickness in the same areas of the left ventricle has not been defined. Therefore, the present study was undertaken in which LV wall thickness and the percent area of myocardium disorganized were systematically compared in the same tissue section. No correlation was identified between wall thickness and the amount of myocardium disorganized in the same tissue sections, either when calculated separately for the ventricular septum, and anterolateral and posterior free walls, or when expressed for all 3 regions combined. Therefore, in patients with HC: (1) disorganized myocardial architecture is not confined to greatly thickened portions of the LV wall, but regions of the left ventricle with normal or only mildly increased thickness may also be disordered; and (2) whereas both LV wall thickening and cellular disorganization are manifestations of the primary cardiomyopathic process, these 2 morphologic features do not appear to be directly related with regard to their extent and distribution within the LV wall. These observations will potentially enhance understanding of the relation between LV structure and compliance in HC.