Impact of Different Right Ventricular Lead Positions on QRS Complex Duration Post Cardiac Resynchronization Therapy Device Implantation

Abstract

Abstract Aim and objectives The aim of the study was to evaluate the effect of different RV lead positions on QRS complex duration post CRT device implantation in patients indicated for CRT as a treatment of chronic heart failure based on the recommendations of ESC guidelines for diagnosis and treatment of acute and chronic heart failure published in 2016 and to assess the effect of change of QRS complex duration and morphology according to different RV lead positions on clinical response. Patients and Methods This study included 100 patients (age 60.02 ± 7.18) post CRT device implantation presented for follow up at electrophysiology clinics of the cardiology department of Ain Shams university hospitals at least 3 months post CRT device implantation, during the period form from December 2020 till May 2021. The patients were divided into 2 groups according to the site of RV lead implantation after confirmation of the RV lead position by fluoroscope in Right anterior oblique (RAO) and left anterior oblique (LAO) views, 54 patients had the RV lead implanted in the RV Apex (RVA n = 54) and 46 patients had the RV lead implanted in the RV Septum (RVS n = 46). Results OF the total 100 patients that enrolled in our study the rate of non-responders was 19% of the patients showed no clinical improvement, no improvement of NYHA class by at least one grade, 30% of the patients were non-Echocardiographic responders, no improvement of LVEF (Δ EF) by at least 5% with no decrease of LVES diameter by at least 15%, and 15% of the patient were nonECG responders, delta QRS (ΔQRS) didn`t increase by at least 20%. There was no significant difference between the two groups regarding clinical response (NYHA class) (P-value = 0.583), LVEF (Δ EF 6.26 ± 1.64 in RVS group vs. 6.07 ± 1.67 in RVA group, P-value = 0.575) LVES diameter (47.70 ± 8.03 in RVS group vs. 45.39 ± 7.48 in RVA group, P-value = 0.141) or QRS complex narrowing (ΔQRS 60.93 ± 24.68 in RVS group vs. 54.07 ± 26.12 in RVA group, P-value = 0.182). There was no significant difference in the rate of non-responders between the two groups (clinical non responders in RVS group n = 8 vs. RVA group n = 11, P value = 0.547) (Echo non responders in RVS group n = 13 vs. RVA group n = 17, P value = 0.726) (ECG non responders in RVS group n = 6 vs. RVA group n = 9, P value = 0.613), There was an inverse relationship between ΔQRS and clinical response (NYHA) class post CRT device implantation in both RVS and RVA groups (P value 0.016 in RVS group, P value 0.007 in RVA group). Conclusion The study demonstrates that septal RV pacing in CRT is non-inferior to apical RV pacing regarding the primary objective of the study regarding clinical outcome, narrowing of QRS complex (ΔQRS) or LV reverse remodeling, thus no recommendation for optimal RV lead position can hence be drawn from this study. Also, delta QRS complex duration may be used as indicator for electric remodeling and CRT response.