Leadless left ventricular endocardial pacing in nonresponders to conventional cardiac resynchronization therapy

Abstract

Background: Endocardial pacing may be beneficial in patients who fail to improve following conventional epicardial cardiac resynchronization therapy (CRT). The potential to pace anywhere inside the left ventricle thus avoiding myocardial scar and targeting the latest activating segments, may be particularly important. The WiSE-CRT system (EBR systems, California) reliably produces wireless, endocardial left ventricular (LV) pacing. The purpose of this analysis was to determine whether this system improved symptoms or led to LV remodelling in patients who were non-responders to conventional CRT. Method: An international, multicentre registry of patients who were non-responders to conventional CRT and underwent implantation with the WiSE-CRT system was collected. Results: 22 patients were included; 20 patients underwent successful implantation with confirmation of endocardial biventricular pacing and in 2 patients there was failure of electrode capture. 18 patients proceeded to 6-month follow-up; endocardial pacing resulted in a significant reduction in QRS duration compared with intrinsic QRS duration (26.6±24.4ms; P = 0.002) and improvement in left ventricular ejection fraction (LVEF) (4.7±7.9%; P = 0.021). The mean reduction in left ventricular end-diastolic volume was 8.3±42.3cm3 (P = 0.458) and end-systolic volume (LVESV) was 13.1±44.3cm3 (P = 0.271), which were statistically non-significant. Overall, 55.6% of patients had improvement in their clinical composite score and 66.7% had a reduction in LVESV ≥15% and/or absolute improvement in LVEF ≥5%. Conclusion: Non-responders to conventional CRT have few remaining treatment options. We have shown in this high risk patient group, the WiSE-CRT system results in improvement in their clinical composite score and leads to left ventricular remodelling.