Q: Why endomyocardial biopsy has high false negative results in cardiac sarcoidosis?


Answer: Endomyocardial biopsy in cardiac sarcoidosis has a very high rate of false negative results due to two reasons. First, the disease has a patchy distribution. And second, myocardial granulomas usually affects the basal and lateral left ventricular (LV) wall regions which are difficult to reach for biopsy.


Reference: 

Uemura A, Morimoto S, Hiramitsu S, et al. Histologic diagnostic rate of cardiac sarcoidosis: evaluation of endomyocardial biopsies. Am Heart J 1999; 138:299.