Features of endomyocardial biopsy specimens (EMB) have been analyzed extensively; however, the frequency, distribution, and associations of adipose tissue in EMB taken from patients with failing hearts have received less attention. We analyzed morphologically and morphometrically EMB from 241 patients (159 male, 82 female, mean age 46.6 years, range 18-76) for whom six diagnostic clinicopathologic categories (including normality) were separately defined. The mean surface area of EMB, mean area of quantifiable adipose tissue, and percentage area attributable to fat were determined by computer-based morphometry to be 6.5 mm2, 0.4 mm2, and 6.5%, respectively. The mean number of biopsy pieces, number of pieces with fat, and percentage of pieces with fat were 4.1, 1.1, and 28.9%, respectively. Patients with arrhythmogenic right ventricular dysplasia had greater percentage area attributable to fat (19.8% vs. 8.9%; p < 0.0027) and greater number of pieces with adipose tissue (2.9 vs. 1.0, p < 0.0001) than did patients in diagnostic categories with the next most fatty EMB. There were no differences between males and females in EMB surface area fat or percentage of pieces with fat. Older patients (above the mean age) had greater adipose tissue in EMB (percentage area attributable to fat) than did younger patients (8.1% vs. 4.8%; p < 0.01). Body mass index (kg/m2) did not correlate with percentage EMB tissue area attributable to fat. Larger EMBs (above the mean area) were neither more frequently nor more involved by fat than were smaller biopsy specimens (6.4% vs 6.6% fat, respectively). Typically, adipose tissue in EMB percolated widely through the myocardium, and the mean number of EMB pieces did not influence the likelihood of finding fat deposits. Fat was intimately associated with blood vessels and was frequently associated with small areas of interstitial and replacement fibrosis. The high frequency of adipose tissue in EMB and the relatively large area constituted by fat in some EMB supports autopsy observations that focal and widespread fatty infiltration of the right ventricular endomyocardium is to be expected and reflected in EMB sampling. Excessive myocardial fat may play a pathogenic role in cardiomyopathy.
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Cardiology and Cardiovascular Medicine