Electrogram-guided endomyocardial biopsy yield in patients with suspected cardiac sarcoidosis and relation to outcomes

Objective: Endomyocardial biopsy (EMB) is a useful diagnostic tool though the yield may be limited in many myocardial diseases. Data on the diagnostic yield and prognostic significance of EMB guided by abnormal electrograms (EGM-Bx) in suspected cardiac sarcoidosis (CS) are scarce. Methods: Seventy-nine patients (mean age: 56 ± 12 years; 61% men) with suspected CS based on clinical and imaging features underwent right or left ventricular EGM-Bx guided by electroanatomic mapping. Tissue samples were obtained from sites with abnormal EGMs and/or abnormal cardiac imaging. The diagnostic yield of EGM-Bx was evaluated in reference to histopathologic analysis. Left ventricular assist device (LVAD) and transplantation-free survival were compared between patients with positive and negative EGM-Bx for CS. Results: A total of 254 samples were obtained from abnormal EGM sites, and 126 samples from normal EGM sites guided by pre-procedure imaging findings. Abnormal histopathology was noted in 65 (26%) and 10 (8%) samples from abnormal and normal EGM sites, respectively. Histopathology confirmed CS in 16 (20%) patients, while an alternative tissue diagnosis emerged in 10 (13%) patients. Abnormal EGMs at the biopsy site had sensitivity 89% and specificity 33% for a histopathologic diagnosis of CS. LVAD and transplantation-free survival were not significantly associated with the EGM-Bx result (log-rank p =.91). Conclusion: In patients with suspected CS, abnormal EGM-Bx has high sensitivity and low specificity for establishing a definite CS diagnosis. Consideration of substrate abnormalities apparent on preprocedural imaging as an adjunct for selection of biopsy sites may further improve EGM-Bx yield.