96-38: Intermediate and long term outcomes of permanent LV coronary sinus pacing without an RV lead- two LV leads may be better than one!

Abstract

Purpose: Chronic LV pacing may be superior to RV pacing and the placement of an RV lead may result in damage to the tricuspid valve, particularly in the case of a prosthetic or repaired valve. The purpose of this study is to evaluate the safety and feasibility of permanent pacing the LV via the coronary sinus with one or two LV leads without the use of an RV pacing lead. Methods: Consecutive patients referred for permanent pacemaker placement following tricuspid replacement or repair and selected patients referred for complete heart block who did not fit the criteria for standard biventricular pacing at the time of implant were included in this series. Patients in the latter group were implanted in the pre-Block HF era. Patients who received a standard single or dual chamber pacemaker had a single bipolar left ventricular lead placed in a lateral branch of the coronary sinus. Patients receiving a biventricular pacemaker had a quadripolar left ventricular lead placed in a standard lateral branch of the coronary sinus and a second bipolar left ventricular lead placed in an anterior branch of the coronary sinus. All patients in sinus rhythm received an atrial lead positioned in the right atrial appendage. Patients were followed in the pacemaker clinic at 4 weeks post implant, three months and then every six months thereafter. We evaluated LV pacing thresholds at implant and on going success of pacing therapy. Results: Eleven patients, mean age 65.9 ± 3.8 SEM, were included in this study. Two patients were pacemaker dependent at the time of pacemaker implant. Four patients had a bioprosthetic tricuspid valve and one had undergone a tricuspid valve repair. One patient had severe tricuspid regurgitation following a previously implanted pacemaker and was status post extraction of the RV lead. Two patients had cardiomyopathies felt to be rate related and planned AV node ablations. One patient had severe left ventricular dysfunction immediately post aortic valve replacement. One patient had a dilated cardiomyopathy but an ejection fraction >35%. One patient had permanent atrial fibrillation and cardiomyopathy thought to be due to a rapid ventricular response whose LV function had normalized post implanted biventricular ICD and AV node ablation. This patient presented with an RV lead fracture and a chronic bipolar LV lead. Eight patients received a dual chamber pacemaker pulse generator (PG), 2 a biventricular PG and 1 a single chamber pacemaker. All patients underwent successful device implant and there were no peri-operative complications. LV pacing thresholds at implant were 1.8 ± 0.3 SEM Volts @ 0.5 msec in patients with a single LV lead and 0.7 ± 0.2 SEM Volts @ 0.5 msec in patients with two LV coronary sinus leads. One patient with a single LV lead required the addition of an RV lead at 10 months post implant due to diaphragmatic stimulation. One patient with a single LV lead experienced diaphragmatic pacing if pacing outputs were increased more than 1 volt above threshold. No other patients experienced any pacing related issues during a mean follow up of 22.6 ± 6.7 SEM months. Two patients met the criteria for a biventricular ICD a mean of 8 months post pacemaker implant and were upgraded. Conclusions: Intermediate to long term permanent pacing with only LV coronary sinus lead(s) and no RV lead is promising in terms of safety and feasibility. The use of a biventricular pulse generator with two LV leads including one quadripolar lead may result in lower pacing thresholds and more pacing vector options to avoid diaphragmatic pacing and requires further evaluation.