Emergence of atrioventricular nodal reentry tachycardia after surgical or catheter ablation for atrial fibrillation: Are we creating the arrhythmia substrate?

Background Atrioventricular nodal reentry tachycardia (AVNRT) is common in adults and often involves reentry through ≥2 atrioventricular nodal-atrial connections. Although AVNRT can be a trigger for atrial fibrillation (AF), we have observed new-onset AVNRT after AF ablation procedures. Objective The purpose of this study was to determine whether ablation involving the septum or proximal coronary sinus (CS) during AF ablation may create a substrate favorable for AVNRT. Methods Cases of ablation for persistent AF who required a repeat ablation procedure between 2009 and 2016 were reviewed for diagnosis of AVNRT. Results Nine patients were identified; the mean age was 54 years, 7 (78%) were men, 2 with prior Cox-MAZE procedures, 5 had radiofrequency ablation (RFA) for AF, and 2 patients had both RFA and Cox-MAZE procedure. None of the patients with prior RFA had dual atrioventricular node physiology at baseline. All patients had evidence of atrial fibrosis in the septum or proximal CS, and 6 had undergone ablation either at the septum or the CS ostium/body, and the other 3 had received inferior mitral lines at a surgical MAZE procedure. All had typical AVNRT inducible that was abolished by slow pathway ablation, but 5 required ablation in the roof of the CS or on the mitral valve annulus. Conclusion Ablation involving the septum or proximal CS may create a substrate favorable for AVNRT. These findings are consistent with the theory that the posteroseptal left atrium and its connections to the CS are critical for some forms of AVNRT.