Cardiomyopathies frequently lead to conduction system disease and/or arrhythmias necessitating device therapy, catheter ablation, or both. Endomyocardial biopsy (EMB) is avoided with recent right ventricle (RV) lead implants and optimal timing is uncertain. We determined outcomes of EMB at the time of ablation or device implantation procedures.

We retrospectively analyzed patients undergoing EMB during their electrophysiological procedure between January 2014 and July 2016. EMB was obtained using cephalic/subclavian access prior to device implants or femoral venous/arterial access after ablation procedures. Sites of electrogram (EGM) abnormality and/or scar on imaging were targeted when possible.

Twenty-five patients (23 male, 59.7 ± 15.1 years) were included. Sixteen had reduced ejection fraction. EMB was performed during device implants in 9, during ablation in 13, and during combined procedures in 3 patients. RV and left ventricle (LV) EMB were obtained in 19 and 6 patients, respectively. 3.9 ± 1.8 samples/patient (median 4) were obtained. EMB yielded a diagnosis in 7 (28%, all RV) patients (4 cardiac implantable electronic device implantation, 2 ablation, and 1 both): cardiac amyloid in 4, lymphocytic myocarditis in 2, and cardiac sarcoid in 1. All 7 patients had imaging or voltage abnormalities in the chamber biopsied. Abnormal but non-diagnostic findings, most commonly fibrotic change, were found in 14 patients. At mean follow-up of 1.1 ± 0.9 years, 5 other patients received a clinical diagnosis (3 cardiac sarcoid, 1 arrhythmogenic cardiomyopathy, and 1 Brugada syndrome/arrhythmogenic cardiomyopathy overlap syndrome). Two patients developed minor device pocket hematomas and one developed pericardial effusion (underwent concomitant epicardial mapping and ablation for VT).

RV or LV EMB can be performed safely during EP procedures and can assist with diagnosis, influencing management. EGM-guided EMB in patients presenting with scar-related VT was low yield for specific pathologies.