Role of concomitant endomyocardial biopsy in non-ischemic cardiomyopathy with ventricular arrhythmias.

BACKGROUND: In patients with non-ischemic cardiomyopathy (NICM) presenting with ventricular arrhythmias (VAs), the diagnostic yield and clinical significance of routine endomyocardial biopsy (EMB) remain unclear. This study aimed to evaluate the diagnostic utility of EMB with electrophysiological procedures in patients with NICM. METHODS: We enrolled 37 consecutive patients with NICM complicated by VAs who underwent EMB during electrophysiological procedures. Clinical history, imaging data, and genetic testing results were collected, and changes in diagnosis based on EMB findings were assessed. RESULTS: The median age was 61 years, and 35 of 37 patients (94.6%) were male. The most common arrhythmia was sustained VT in 27 patients (73.0%), followed by frequent PVCs in 6 (16.2%) and non-sustained VT in 4 (10.8%). Twenty-nine patients (78.4%) underwent catheter ablation, while eight (21.6%) underwent device implantation. EMB identified cardiac amyloidosis in 3 patients (8.1%) via Congo red staining, while the remaining 34 (91.9%) showed nonspecific fibrosis. No complications occurred during EMB. Among the 11 patients (29.7%) who underwent positron emission tomography/computed tomography (PET-CT), six (54.5%) were diagnosed with cardiac sarcoidosis. Genetic testing was performed in 23 patients (62.2%), revealing pathogenic TTN mutations in 2 (8.7%) and an RYR2 mutation (4.3%) consistent with catecholaminergic polymorphic VT. Cardiac MRI was performed in 29 patients (78.4%), with late gadolinium enhancement observed in 2 patients (6.9%) with suspected myocarditis, 1 (3.4%) with suspected sarcoidosis, and 2 (6.9%) with dilated cardiomyopathy. Furthermore, 2 patients (6.9%) showed right ventricular dysfunction with wall motion abnormalities, consistent with arrhythmogenic right ventricular cardiomyopathy. CONCLUSION: EMB can be safely performed during electrophysiological procedures and may aid diagnosis in selected cases, particularly cardiac amyloidosis. However, PET-CT demonstrated greater overall diagnostic utility.