AV junctional ablation allowing more effective delivery of cardiac resynchronization therapy in patients with intra- and interatrial conduction delay.

We report two patients with cardiac resynchronization therapy (CRT) devices and evidence of refractory heart failure in whom impaired intraatrial conduction in one patient, and interatrial conduction in the other, prohibited optimization of the atrioventricular (AV) timing sequence. The patient with intraatrial conduction delay exhibited late right atrial sensing and latency during right atrial pacing that required programming of a short-sensed AV delay and long-paced AV delay (wide differential AV delay). In both patients AV junctional ablation and echocardiography-guided device optimization significantly improved heart failure.