Diagnostic value of disarray in endomyocardial biopsy specimens in hypertrophic cardiomyopathy. A critical report based on distribution of disarray in the subendocardial region of autopsied hearts.

Myocardial fiber disarray in endomyocardial biopsies is considered to be a histologic feature of hypertrophic cardiomyopathy (HCM). To determine whether this disarray is specific for HCM, we examined the distribution of disarray in the subendocardial region in 11 autopsied hearts from patients with HCM and 41 autopsied control hearts. The percent area of disarray in the subendocardial region of the right ventricular side of the septum with maximum septal hypertrophy was 9 +/- 3% in HCM and 4 +/- 2% in the controls (p less than 0.001). The frequency of occurrence of disarray in this area was 38 +/- 10% in HCM and 20 +/- 7% in the controls (p less than 0.001). Disarray covering over 76% of a visual field, although extremely rare, was specific for HCM. In the right ventricular side of the septum in the lower half and in the left ventricular free wall, there was no significant difference between HCM and controls in regard to the percent area of disarray and its frequency of occurrence. In conclusion, although disarray in right ventricular endomyocardial biopsies is considered to be more frequent in HCM than in the controls, too much emphasis should not be placed on disarray in endomyocardial biopsy specimens as a diagnostic criterion for HCM.