Intra-atrial conduction block mimicking atrioventricular nodal block after multiple catheter ablation procedures for atrial tachycardia in a patient with cardiomyopathy.

A 42-year-old woman with a history of cardiomyopathy and multiple ablation procedures for atrial tachycardia developed intra-atrial conduction block that mimicked atrioventricular (AV) nodal block during radiofrequency ablation at the cavotricuspid isthmus. She was treated with atrial pacing (from the coronary sinus), which overcame intra-atrial conduction block and resulted in AV nodal conduction.