The value of endomyocardial biopsy in diagnosis and guiding therapy

Abstract

Endomyocardial biopsy (EMB) is a highly-specialised procedure that is associated with some controversy as to its diagnostic role due to its inconsistency in diagnosing a wide variety of cardiac diseases. Given the advances and sophistication in echocardiography and cardiac magnetic resonance imaging (MRI), the vast majority of cardiac diseases can be diagnosed by these non-invasive procedures. Under-sampling and the fact that biopsy site is limited to the right side of the interventricular septum further limits its value. In spite of all these limitations, there still remains a group of pathological conditions that require biopsy for a conclusive diagnosis such as myocarditis, amyloidosis, sarcoidosis and giant cell myocarditis. Correct patient selection and the quantity of tissue samples impart a significant influence on the accuracy of the diagnosis, and thus the value of EMB is variable for each patient. The purpose of this study was to evaluate the role of EMB in patient care, through its ability to either change clinical diagnosis or alter patient management. Our study was based in a single teaching centre. An audit of cardiac biopsies performed over a 10 year period identified 250 patients. We assessed indications, histology, electron microscopic findings, final clinical diagnosis and how they influenced patient management. A definite diagnosis on histology was given in 44 of 250 patients (17.6%). Non-specific findings were observed in the remaining 206 patients (82.4%). Histology influenced patient management in 73 (29.2%) patients. Histological examination in the remaining 177 biopsies (70.8%) did not provide a definite diagnosis or influence patient management. It was additionally found that the number of tissue fragments sampled has significant impact on diagnostic accuracy. A more accurate diagnosis of 45% was obtained when ≥5 fragments were sampled, as compared to 1-3 fragments where accuracy dropped to 20%. Our study indicated that sampling for electron microscopy has very limited value. We found that of 245 biopsies sampled for electron microscopy, only three biopsies (1.2%) had diagnostically useful findings. In our institution procedure related complications were observed in 7 of 250 patients (2.8%). The diagnostic value of EMB is important but limited. Strict triaging of patients according to clinical suspicion and adequate sampling of tissue may increase useful diagnostic information.

Keywords: Endomyocardial biopsy; cardiac amyloidosis; diagnostic value; electron microscope.