Lessons learned in attempting catheter-based interatrial electrical disconnection for nonpharmacologic rate control of atrial fibrillation or flutter.

PURPOSE: Ablation of atrioventricular (AV) conduction and pacemaker implantation is the therapy of last resort for symptomatic atrial tachyarrythmias when rhythm and rate control fail, but is far from ideal. To evaluate whether interatrial electrical disconnection as a result of catheter ablation is feasible and of potential clinical utility as a means of non-pharmacological heart rate control.

METHODS: Eleven patients with medically refractory atrial fibrillation or left atrial flutter and symptomatic rapid ventricular response were included. The ablation strategy consisted primarily of right atrial ablation of the interatrial electrical connections, which were located by electroanatomical activation maps performed during coronary sinus stimulation. Successive activation maps were performed as each connection was blocked. If the procedure was considered unsuccessful AV nodal ablation was performed.

RESULTS: The coronary sinus ostium was earliest in 10/11 and could be ablated in 5/10 patients. Interatrial conduction block was only achieved in one patient (9.1%). An unexpected AV nodal modulation with an increase in the Wenckebach cycle length (> 50 ms) occurred in 8/11 patients. These patients remained without pacemaker implantation and only 1/8 required AV nodal ablation during the 1-year follow-up. Quality of life questionnaires indicated significant improvement in patients with AV nodal modulation.

CONCLUSION: Interatrial electrical disconnection by right atrial catheter ablation is a not feasible with present day technology. The extensive right atrial septal ablation performed resulted in significant AV nodal modulation in most patients, which persisted and resulted in improvement in quality of life.