The Use of a Quadripolar Left Ventricular Lead Increases Successful Implantation Rates in Patients with Phrenic Nerve Stimulation and/or High Pacing Thresholds Undergoing Cardiac Resynchronisation Therapy with Conventional Bipolar Leads

BACKGROUND Phrenic nerve stimulation (PNS) and high pacing thresholds (HPT) hinder biventricular stimulation in patients (pts) undergoing cardiac resynchronization therapy (CRT). A new quadripolar left ventricular (LV) lead (Quartet 1458Q, St. Jude Medical) with increased number of pacing configuration, might overcome this problem. METHODS All consecutive pts in whom a standard bipolar lead intraoperatively resulted in PNS and/or HPT (≥4.00V/1mV), received, during the same implant, a quadripolar LV lead. Aim of the study was to evaluate acute and short term outcome. RESULTS 26 pts [24 (92%) male, mean age 74±6 years)] with PNS (22 pts; 85%) and HPT (4 pts; 15%) were included. Permanent right ventricular pacing was the reason for broad QRS complex in 4 (15%) pts, whereas all other pts had a left bundle branch block. Severely symptomatic (NYHA Class ≥3) heart failure with reduced ejection fraction (EF 31±9%) was mostly caused by ischemic heart disease (14 pts; 54%). Idiopathic dilated cardiomyopathy and valvular heart disease were diagnosed in 6 (23%) pts each. In most (24/26, 92%) pts the use of the Quartet lead led to successful biventricular pacing due to a significant reduction in intraoperative pacing threshold (5.2V/1.0ms vs. 1.4V/0.8ms; p=0.03), which was maintained (1.2V/0.7ms) at follow-up. PNS never represented reason for failed LV pacing, neither acutely nor during follow-up. CONCLUSION Excessively HPT and/or PNS are frequently encountered when conventional bipolar leads are used for CRT. A new quadripolar LV lead increases the rate of successful biventricular stimulation. Lower pacing threshold and freedom from PNS are maintained at follow-up.