Specificity of cellular and myofibrillar disorientation in hypertrophic obstructive cardiomyopathy.

The specificity of the ultrastructural myocardial abnormalities in hypertrophic obstructive cardiomyopathy (HOCM) is undetermined. We undertook a quantitative study using myocardial biopsy specimens from the subaortic area in a patient with classical HOCM and compared them with hypertrophic left ventricular myocardium from a patient suffering from rheumatic valve disease. Myofibrillar disarray and side-to-side junctions were chosen as strictly quantifiable features. The former was seen as representing intracellular disorganization; the latter was seen as criterion for intercellular disorganization. The results showed that there is no preference for these abnormalities to occur in HOCM. Indeed, intracellular abnormalities more frequently occurred in the hypertrophic myocardium the patient without HOCM. Neither intracellular nor intercellular features can be regarded as specific for HOCM, even in a quantitative sense.