Cardio-neural Pacing to Modulate AV Conduction in Persistent AF Patients - a Feasibility Study

Atrial fibrillation is the commonest arrhythmia with a lifetime risk of one in 3-5. In patients with late stage of persistent atrial fibrillation, rate control is usually preferred over rhythm control. Besides medication therapy, atrioventricular nodal ablation is sometimes required with placement of a pacemaker afterwards. The AV node is being innervated by parasympathetic fibres that modulate its conduction. Ablation in these parasympathetic innervations around the coronary sinus (at the CS ostium or posterior to it) has been shown to be promising for treating vagal mediated syncope. Stimulation of these fibres with high frequency pacing could achieve chronic heart rate suppression in animal model. Intermittent pacing in this area has also been shown to be successful in reducing ventricular rate in atrial fibrillation to prevent inappropriate ICD shock. As a proof-of-concept case, we attempted pacing cardio-neural fibres in one of our patients. Pacing 30Hz at 10mA, 2ms pacing in ostial or postero-septal coronary sinus both resulted in a dose dependent prolongation of VV cycle length during atrial fibrillation. Patient did not complain of discomfort during such pacing. We postulate that pacing these fibers can achieve rate control and avoid the need for rate control medication or AV node ablation in some of these patients. This study aims to evaluate safety and efficacy of temporary cardio-neural pacing (CNP), and collect fluoroscopic images and electroanatomical mapping data on cardio-neural pacing sites.