Evaluation of pathological criteria for diagnosis of hypertrophic cardiomyopathy.

This study aims to evaluate and compare the current pathological criteria for the diagnosis of hypertrophic cardiomyopathy (HOCM). The following criteria were applied to 39 autopsy patients whose hearts showed myofibre disarray: (i) disarray involving more than 5% of ventricular septal myofibres, (ii) asymmetrical septal hypertrophy (ASH), (iii) mirror-image subaortic plaque, and (iv) a positive histologic HOCM index (HHI). Group 1 (27 patients) with greater than 5% ventricular septal myofibre disarray were diagnosed as HCM, whereas group 2 (12 patients) had less than 5% disarray. The mean disarray value in group 1 was 52% compared to 1.2% in group 2. The two groups showed significant differences regarding ASH and in the amounts of myofibre disarray in the free walls of both ventricles. A new finding was that the histologic HOCM index was significantly higher in patients who died suddenly. The HHI was the commonest positive criterion in group 1, followed by ASH and a mirror-image endocardial plaque. None of the current imperfect pathological criteria for the diagnosis of HCM can be used as the 'gold standard'.