Research On A Novel Technique And An Optimized Strategy For Cardiac Resynchronization Therapy

Background: Cardiac resynchronization therapy(CRT)is necessary for patients with heart failure and electro-mechanical dyssynchrony.Conventional biventricular pacing(BVP)is a mainstay for CRT.Conduction system pacing including His bundle pacing(HBP)and left bundle branch pacing(LBBP)has been developed as an increasingly used method for CRT.We have recently proposed a novel technique of bilateral septal pacing(BSP)in combination with coronary venous pacing(CVP)for CRT(BSP-CRT).However,there are no guideline for recommendation on how to choose these techniques.Our optimized strategy for CRT is that HBP、LBBP、BVP and BSP-CRT should be used in sequence for the purpose of achieving paced QRS <130ms.Aim: In the first part of this study,the objective was to compare clinical outcomes between patients who received conventional BVP and received CRT according to the optimized strategy.In the second part of this study,the purpose was to investigate whether BSP-CRT can further improve the electrical resynchronization in comparison with conventional BVP.Methods: The subjects were selected from patients who received CRT in the department of cardiology of General Hospital of Northern Theater Command.Patients who received conventional BVP and received CRT according to the optimized strategy were classified as the conventional BVP group and the optimized strategy group.Clinical outcomes and electrical synchronization improvement were compared between two groups.The novel BSP-CRT technique is performed by interventricular BSP and CVP.BSP captures both sides of interventricular septal myocardium,which is manifested as non right bundle branch block QRS pattern with shortened R wave peak time in lead V6.The success rate of BSP-CRT was recorded.Electrophysiologic characteristics of BSP-CRT and BVP were compared during procedure in every patient with successful BSP-CRT.The clinical outcomes of BSP-CRT were analyzed.Results: A total of 135 patients were enrolled in the first part of this study,aged 65±15years old,including 66 males(48.9%).There were 79 cases in the optimized strategy group and 56 cases in the conventional BVP group.The paced QRS duration were narrowed significantly in both the optimized strategy group and the conventional BVP group(179±9 ms vs 113±12 ms and 173 ± 8 ms vs 146 ±9 ms respectively,both P <0.05).The paced QRS duration in the optimized strategy group was significantly shorter than that in the conventional BVP group(P < 0.05)and the optimal strategy delivered superior QRS narrowing than conventional BVP(65.9 ± 13.6 ms vs 26.5 ± 8.3 ms,P <0.05).The rate of paced QRS duration <130ms after procedure was higher in the optimized strategy group than in the conventional BVP group(93.7% vs 39.3%,P <0.05).The improvement of LVEF in two groups were both significant(48.8±7.9% vs30.0±3.0 % in the optimized strategy group and 38.4±5.4 % vs 31.0 ± 3.0 % in the conventional BVP group;both P < 0.05).The LVEF after procedure was higher in the optimized strategy group than in the conventional BVP group(P < 0.05).Compared with the conventional BVP group,CRT according to the optimized strategy achieved greater LVEF improvement(19.3 ± 7.3% vs 7.4 ± 4.9%,P < 0.05)and higher response rate(91.1 % vs 67.9 %,P< 0.05)and super response rate(51.9 % vs 19.6 %,P< 0.05).In the second part of this study,17 patients were attempted for BSP-CRT in the optimized strategy group.The baseline QRS duration was 184 ± 13(160-210)ms.BSP-CRT was successfully achieved in 15 patients with a success rate of 88%(15/17).Among these 15 patients,QRS duration significantly narrowed to 155 ± 9 ms during BVP and further to 121 ± 10 ms during BSP-CRT respectively(both P < 0.001).Compared with BVP,the QRS duration of BSP-CRT was further shortened by 22%(-34 ms [95% confidence interval:-38 to-29 ms];P < 0.001).At 6-month follow-up,LVEF improved significantly(40±7% vs 29±5%,P < 0.001).Conclusions: BSP-CRT delivered superior acute electrical synchronization to BVP.The optimized strategy for CRT,which is that HBP、LBBP、BVP and BSP-CRT should be used in sequence for the purpose of achieving paced QRS <130ms,improved clinical outcomes compared with BVP.