Study On The Duration Of QRS Notching And Left Bundle Branch Pacing Response In Patients With True Left Bundle Branch Block And Heart Failure

Purpose:Chronic heart failure(CHF)is a group of clinical syndromes caused by ventricular diastolic filling and/or impaired systolic ejection function.It is the end-stage manifestation of various cardiovascular diseases.While cardiac resynchronization pacing(CRT)has a mainstay role in existing non-drug treatments,left bundle branch pacing(LBBP)achieves CRT by correcting blocked left bundle branches,which is a more physiological CRT choice.Some studies believe that the duration of QRS notching in patients with true left bundle branch block(t-LBBB)represents the conduction process of electrical activation from the left ventricular membrane surface of the ventricular septum to the posterior wall of the left ventricle,and the patient’s left ventricular end-diastolic heart cavity diameter is related to the conduction function of the left ventricular conduction system and may affect the responsiveness of CRT.This study intends to retrospectively analyze the relationship between the duration of QRS notching and postoperative responsiveness of LBBP in patients with t-LBBB who received LBBP in our hospital.To clarify whether the duration of QRS notching has the ability to predict postoperative responsiveness of LBBP.Methods:This study analyzed 19 patients who were treated with LBBP who were admitted to the Department of Cardiology of the First Affiliated Hospital of Kunming Medical University between October 2018 and December 2020.The 19 patients met the 2016 European Society of Cardiology Heart Failure Guidelines CRT Ia indications and met the Strauss t-LBBB diagnostic criteria.As there are few researches on the duration of QRS notching,the description of the duration of QRS notching ranges from 40-70ms,and there is a lack of specific quantification and classification standards.In order to exclude the difference caused by the position of the chest lead electrodes,this study selected lead I QRS wave as the observation object and divided the subjects into study groups according to the median duration of QRS notching in lead I of the patient’s preoperative ECG.(The duration of QRS notching in lead I<median)and control group(the duration of QRS notching in lead I≧median).All enrolled patients continue the anti-heart failure drug treatment program recommended by guidelines such as diuretics,β-blockers,ARNI or ACE or ARB,and adjust the best drug type and dose according to the patient’s condition.According to the patient’s cardiac color Doppler ultrasound index and the duration of QRS notching,the frequency-adaptive atrioventricular delay algorithm is used to optimize the pacing interval between the right atrium and the left bundle branch region to achieve cardiac resynchronization.Take the 6-month follow-up data to retrospectively analyze the QRS wave duration before and after CRT,LVEF,LVFS,the size of each heart chamber,NYHY classification,clinical symptoms,etc.,and comprehensively evaluate the CRT responsiveness.Evaluation criteria for responsiveness This study adopted the identification criteria of an ultrasound prediction of CRT responsiveness study at the University of Oslo:(1)Responsive:①The status or improvement of at least one level of NYHA;②LVEF increased by 5%③Left ventricular systolic volume(LVESV)Decrease by 10%;④BNP decrease by 10%.(2)Hyperreaction:LVEF increases by 15%or the absolute value is greater than 45%.(3)No response:Patients who died of worsening heart failure or insufficient heart transplantation during the follow-up period were regarded as non-responders.All data were statistically analyzed by SPSS25.0 software,and the P value p<0.05 indicated that the difference was statistically significant.Results:1.Determine the median of the duration of QRS notching in I lead(QRSdI notching)as 53ms.Divide all patients into study group(the duration of QRS notching in lead I<53ms)and control group(the duration of QRS notching in lead I≧53ms).There was no significant difference in clinical data such as age,gender,underlying disease,heart failure time,preoperative QRS duration,LVEF,LVFS,LVEDD,LADD,LVESV,BNP,NYHA and other clinical data of the first two groups.2.Comparison of CRT responsiveness indexes between the two groups of patients before and after surgery:In the study group,9 patients were included,1 patient did not respond,4 patients overreacted.The data of the patients in the study group were compared before and after the operation;the QRS duration,LVEF,LVFS,BNP,etc.of the patients after the operation were improved statistically compared with the preoperative Academic difference(P<0.01).Compared with preoperative improvement,LVEDD was statistically different(P<0.05).In the control group,10 patients were enrolled,2 patients had no response after operation,and 2 patients had overreaction.The postoperative QRS duration and BNP of the patients were significantly improved compared with the preoperative improvement(P<0.01).LVEF,LVFS,compared with preoperative improvement were statistically different(P<0.05).).3.Comparing the echocardiographic indexes,BNP,NYHA and the changes of the above indexes at the last follow-up after the operation of the two groups with the preoperative changes,the results show:Compared with the control group(the duration of QRS notching in lead I≧53ms),the study group(the duration of QRS notching in lead I<53ms))Postoperative LVEF,LVEDD,LVESV,BNP were significantly improved(P<0.05),and LVEF,LVFS,LVEDD,LVESV,and the study group had more significant changes,the difference was statistically significant(P=0.05)Conclusion:1.The duration of QRS notching in patients with t-LBBB may be related to the patient’s responsiveness after LBBP.Patients with shorter duration of QRS notching may benefit more from LBBP.2.LBBP can improve the heart function indexes of heart failure patients with t-LBBB.