Comparison of amount of myocardial cell disorganization in operatively excised septectomy specimens with amount observed at necropsy in 18 patients with hypertrophic cardiomyopathy.

The extent of cardiac muscle cell disorganization in excised septectomy specimens in 18 patients was compared morphometrically with that observed at necropsy when these patients died after operation. Disorganization was present in all 18 patients at necropsy and was extensive (5 percent or greater) in 16 of the 18. In contrast, there was no disorganization in the operative specimens of three patients and only a trivial amount (less than 1 percent) in five others. Disorganization extensive enough (5 percent or greater) to suggest hypertrophic cardiomyopathy was present in the operative specimens of only 6 of the 18 patients. The mean (+/- standard error of the mean) area of disorganization at necropsy was 20 +/- 3 percent compared with 7 +/- 2 percent in the operative specimens (p less than 0.001). Thus, histologic examination of operatively excised septectomy specimens is of limited value in confirming the diagnosis of hypertrophic cardiomyopathy.