Cardiac resynchronization therapy (CRT) is sometimes complicated by elevated pacing thresholds and phrenic nerve stimulation (PNS), both of which may require that the coronary sinus lead be repositioned. The purpose of this study was to evaluate the performance of a novel quadripolar electrode lead and cardiac resynchronization therapy-defibrillator (CRT-D) device that enables electrical repositioning, potentially obviating a lead reposition procedure.Methods and results
Patients indicated for CRT were enrolled and received a quadripolar electrode lead and CRT-D device (Quartet®model 1458Q and Promote Q®; St Jude Medical, Sylmar, CA, USA). Electrical data, and the presence of PNS during pacing from each left ventricular (LV) configuration, were documented at pre-hospital discharge and at 1 month. Seventy-five patients were enrolled and 71 were successfully implanted with a Quartet®lead. Electrical measurements were stable over the follow-up period. Ninety-seven per cent (64 of 66) of patients had one or more programmable configurations with a threshold <2.5 V and no PNS vs. 86% (57 of 66) if only conventional bipolar configurations were considered. Physicians were able to use the increased programming options to manage threshold changes and PNS.Conclusion
The new quadripolar electrode LV lead provides more programming options to address common problems faced when managing CRT patients. Electrical measurements from new vectors are comparable with conventional configurations. Furthermore, 11% of patients in the study suffered PNS on all conventional bipolar vectors.