Accessory Pathways in Arrhythmogenic Right Ventricular Cardiomyopathy: A Two-Case Series and Literature Review.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiomyopathy characterized by fibrofatty replacement of ventricular myocardium, associated with ventricular arrhythmias and sudden cardiac death (SCD). While supraventricular arrhythmias occur in approximately 25% of ARVC patients, the coexistence of accessory pathways is exceptionally rare, particularly concealed pathways without ventricular pre-excitation. CASE PRESENTATION: We describe two young patients with ARVC and concealed accessory pathways. Case 1: A 27-year-old male with family history of SCD presented with supraventricular tachycardia mediated by a left lateral retrograde-only accessory pathway. Following successful ablation, sustained ventricular tachycardia (VT) was inducible, prompting implantable cardioverter-defibrillator (ICD) implantation. Case 2: A 22-year-old female survived out-of-hospital cardiac arrest. Cardiac MRI revealed right ventricular aneurysms and late gadolinium enhancement. Electrophysiological study demonstrated a decremental right posterior pathway consistent with permanent junctional reciprocating tachycardia (PJRT). Ablation successfully eliminated the tachycardia, and an ICD was implanted for secondary prevention. DISCUSSION: Both patients exhibited concealed accessory pathways with exclusive retrograde conduction-one fast, one decremental-without surface ECG pre-excitation. This rare association increases arrhythmic burden and risk of inappropriate ICD therapies. Catheter ablation was essential for eliminating supraventricular tachycardias and preventing ICD complications. Literature review confirms that while atrial fibrillation and flutter are relatively common in ARVC, accessory pathways remain exceptionally rare. CONCLUSION: The coexistence of ARVC and concealed accessory pathways is exceedingly rare. Recognition is crucial, as catheter ablation prevents supraventricular arrhythmias and inappropriate ICD therapies, while ICD implantation remains essential for protection against malignant ventricular arrhythmias.