| Summary: | 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 (≥4.00 V/1 mV), 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 (5.2 V/1.0 ms vs. 1.4 V/0.8 ms; p=0.03), which was maintained (1.2 V/0.7 ms) at follow-up. PNS never represented reason for failed LV pacing, neither acutely nor during follow-up.
Conclusions: 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.
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