Myocardial biopsy in patients with hypertrophic cardiomyopathy: correlations between morphologic and clinical parameters and development of myocardial hypertrophy under medical therapy.

Left ventricular biopsies from 38 patients with hypertrophic cardiomyopathy (HOCM 28, HNCM 10) were investigated to evaluate possible correlations between morphological and clinical parameters. No correlation was found between the degree of myocardial hypertrophy (muscle cell diameter), nuclear size of the myocytes, fibrous tissue content and various clinical data such as pressure gradient, left ventricular end-diastolic pressure, Sokolow index and heart volume. In 11 patients with HOCM, a second biopsy was performed after medical therapy (verapamil, n = 9; propranolol, n = 2) over 33 +/- 12 months. Increasing myocardial hypertrophy (cell diameter 16.2 +/- 4.4 mu vs. 20.3 +/- 4.2 mu) was observed in all 11 patients. The interstitial fibrous tissue content increased from 5.7 +/- 6.3 to 12.7 +/- 6.8%. The volume fraction of myofibrils decreased (48.8 +/- 2.7 vs. 43.6 +/- 5.3%). The morphological changes were observed regardless of the clinical outcome which was improved in four, unchanged in five and worsened in two cases. The underlying hypertrophic process in HCM seems to be slowly progressive in most patients and cannot be influenced by medical treatment.