Background: Delivery of cardiac resynchronisation therapy (CRT) using conventional systems can be limited by sub-optimal venous anatomy. The WiSE-CRT (EBR Systems, Sunnyvale, CA, USA) has been approved for use with existing right-sided systems. We report the case of a CRT recipient with a left ventricular (LV) lead in the middle cardiac vein (MCV) and who subsequently developed right ventricular (RV) lead failure.
Objective: To describe the first-ever use of multisite LV pacing in a patient with the WiSE-CRT system.
Results: A 73-year old male with ischemic heart failure had received CRT-D using a bipolar LV lead in the MCV. The RV lead developed loss of sensing and capture 3 years on, leading to LV-only pacing. The patient deteriorated and echocardiography showed an LV ejection fraction (EF) of 17%. A venogram showed an occluded subclavian vein. Options were discussed and consent for a change to CRT-P combined with a WiSE-CRT implant was obtained. Day 1 involved the implant of the WiSE-CRT system transmitter under general anesthesia. The CRT-D generator was replaced with a CRT-P, the RV ICD lead pins were capped and both atrial and LV lead parameters were tested and satisfactory. On day 2, under conscious sedation, the receiver electrode was inserted using a retrograde transaortic approach and deployed on the endocardial aspect of the basal anterolateral LV wall. The existing LV lead was used to trigger the WiSE-CRT system, providing simultaneous LV and RV pacing. The AV delay was optimized to 150 ms to allow fusion with intrinsic cardiac conduction, with negative AV hysteresis programmed on (delta -20ms). The patient was seen in the research clinic 10 days and 6 months later, as per protocol. An acute QRS narrowing from 160ms (baseline) to 117ms (paced) was noted at implant. At 6 months, further improvement was noted with a QRS duration of 70ms; a reduction in LV end-systolic volume of 49%; an increase in EF to 41%; and an improvement in global longitudinal strain from -8.8% to -14.9%.
Conclusion: This report on the first-in-man use of fusion-based multisite LV pacing using a leadless endocardial pacing system demonstrates it is possible to synchronise the WiSE-CRT system with an LV lead, providing CRT to patients with sub-optimal coronary vein anatomy.