Background: It has been proposed that multisite atrial pacing (MSAp) restores atrial electrical activation and prevents atrial fibrillation recurrence; however, single-site Bachmann's bundle pacing (BBp) has also been reported as providing effective atrial resynchronization. Coronary sinus pacing (CSp) leads to reversed impulse propagation within the atria.
Methods and results: Acute echocardiographic examination was performed in 15 healthy subjects, and in 25 patients with sinus node dysfunction and recurrent atrial fibrillation during MSAp (atrial leads in the BB area and CS ostium), and single-site BBp and CSp. Regional atrial synchrony was assessed by tissue Doppler echocardiography. Pacing mode had no effect on stroke volume. CSp resulted in right atrial filling diminution, shortened mechanical atrioventricular delay in the right heart and diminished right ventricular inflow. The magnitude of reversion of the physiological right-to-left atrial contraction sequence was most prominent during CSp (15+/-11, 12+/-23, 3+/-21, 42+/-23 ms; control, MSAp, BBp, CSp respectively, P<0.0001). BBp provided the best atrial contraction synchrony, and had a comparable effect on global cardiac function to MSAp.
Conclusions: Single-site BBp provides comparable hemodynamics to MSAp and is sufficient to restore atrial contraction synchrony. Single-site CSp induced echocardiographic pacemaker syndrome in the right heart.