Pathology of radiofrequency catheter ablation of the atrioventricular node

Catheter ablation of the atrioventricular node is now the treatment of choice for definitive management of some supraventricular tachyarrhythmias. Radiofrequency current is used as the energy source in most centers. We describe a 67-year-old woman who had rheumatic mitral valve disease and chronic atrial fibrillation with rapid ventricular response. She underwent successful radiofrequency catheter ablation of the atrioventricular node, followed by permanent pacemaker insertion. She required mitral valve replacement 16 months later and died postoperatively of left ventricular failure. At autopsy, there were patches of organized endocardial thrombus and discrete endocardial and myocardial fibrous scar at the ablation sites, replacing most of the atrioventricular node. The long-term pathologic changes after atrioventricular node ablation with radiofrequency current, used in a clinical setting, have not been previously described and are illustrated here.