Permanent Left Atrial Pacing:

Left atrial pacing is feasible via the coronary sinus. However, long-term characteristics of coronary sinus pacing parameters are largely undefined as yet. This study assessed the feasibility and long-term pacing parameters of coronary sinus pacing. Twenty four patients (13 men, 11 women) with a history of paroxysmal AF refractory to drug therapy underwent biatrial pacemaker implantation. Leads were sited in the high right atrium or right atrial appendage and in either proximal (PCS) or distal coronary sinus (DCS). Pacemaker parameters were measured at implant, 24 hours postimplant, 1 month, 3 months, and at 3 monthly intervals over a period of 2 years. Threshold, impedance, and energy requirements (E = Threshold2/impedance x pulse width) were measured. There was one lead displacement from the PCS within 24 hours postimplant. There were no other acute or chronic complications. The energy values at implant and at 2 years were 0.49 +/- 0.47 and 2.18 +/- 1.69 mJ for the PCS leads and 0.94 +/- 1.47 and 1.27 +/- 0.75 mJ for the DCS leads. P values were >0.05 at all points and suggested no significant difference between the two sites over the long-term. Chronic coronary sinus pacing is a safe and feasible technique. There was no significant difference in energy parameters for leads positioned in the proximal or distal coronary sites. The trends seen at both sites for chronic changes in pacing characteristics are analogous to those described for endocardial leads at other sites.