Left bundle branch pacing set to outshine biventricular pacing for cardiac resynchronization therapy?

The deleterious effects of long-term right ventricular pacing necessitated the search for alternative pacing sites which could prevent or alleviate pacinginduced cardiomyopathy.Until recently,biventricular pacing(BiVP)was the only modality which could mitigate or prevent pacing induced dysfunction.Further,BiVP could resynchronize the baseline electromechanical dssynchrony in heart failure and improve outcomes.However,the high non-response rate of around 20%-30%remains a major limitation.This non-response has been largely attributable to the direct non-physiological stimulation of the left ventricular myocardium bypassing the conduction system.To overcome this limitation,the concept of conduction system pacing(CSP)came up.Despite initial success of the first CSP via His bundle pacing(HBP),certain drawbacks including lead instability and dislodgements,steep learning curve and rapid battery depletion on many occasions prevented its widespread use for cardiac resynchronization therapy(CRT).Subsequently,CSP via left bundle branch-area pacing(LBBP)was developed in 2018,which over the last few years has shown efficacy comparable to BiVP-CRT in small observational studies.Further,its safety has also been well established and is largely free of the pitfalls of the HBP-CRT.In the recent metanalysis by Yasmin et al,comprising of 6 studies with 389 participants,LBBPCRT was superior to BiVP-CRT in terms of QRS duration,left ventricular ejection fraction,cardiac chamber dimensions,lead thresholds,and functional status amongst heart failure patients with left bundle branch block.However,there are important limitations of the study including the small overall numbers,inclusion of only a single small randomized controlled trial(RCT)and a small follow-up duration.Further,the entire study population analyzed was from China which makes generalizability a concern.Despite the concerns,the meta-analysis adds to the growing body of evidence demonstrating the efficacy of LBBP-CRT.At this stage,one must acknowledge that the fact that still our opinions on this technique are largely based on observational data and there is a dire need for larger RCTs to ascertain the position of LBBPCRT in management of heart failure patients with left bundle branch block.

Cardiac Resynchronization Therapy in Heart Failure in Sub-Saharan Africa Environment: Experience of the Principal Hospital of Dakar (Senegal)

Background: Heart failure is a major public health challenge in sub-Saharan Africa. In patients with chronic Heart Failure and cardiac desynchrony, studies have suggested that cardiac resynchronization, can improve cardiac function and the quality of life of patients. However, in Sub-Saharan Africa, very few studies have been done on cardiac resynchronization which is in its infancy. The aim of this study is to report the local data from our hospital. Method: It was a transversal, descriptive and analytical study conducted from November 2019 to September 2022 at the Cardiology Department of the Principal Hospital of Dakar. Results: Twelve patients were implanted for Cardiac Resynchronization Therapy (CRT). The sex ratio was 8 males/4 females. The average age was 67 ± 11 years. Ten patients had non-ischemic heart disease and the two others had ischemic one. All of them had NYHA III or IV scores before CRT. The Quality of Life (QOL) was judged as poor by all of the patients. The average duration of QRS was 156 ± 9 ms. 27.9% ± 5% was the mean Left Ventricular ejection fraction (LVEF). Complications occur in 3/12 patients (25%). It was one CS vein dissection, one micro LV lead dislodgement and one phrenic nerve stimulation. Nine patients, who were considered as responders, had an improvement of QOL and NYHA, the LVEF increased and the end-diastolic dimension, and the duration of the QRS interval all decreased. Two patients do not respond and one (1) who had permanent atrial fibrillation, was a secondary responder after an atrioventricular junction ablation. Conclusion: Cardiac resynchronization is a therapy that improves the QOL of patients, the LVEF and reduces the duration of the QRS interval. However, this procedure is not without risk of complications. In sub-Saharan Africa, the major challenge is to improve the financial accessibility of this therapy for the population.

Effect of serum γ-glutamyltranferase and albumin levels on the response to cardiac resynchronization therapy in the elderly

Background Several liver function tests have been identified as predictors of hospitalization for heart failure(HF) and death in patients with chronic HF. The relationship between serum γ-glutamyltranferase(GGT) and albumin(SA) levels with the response to cardiac resynchronization therapy(CRT) has not been reliably determined. The aim of the study was to evaluate the impact of liver function tests on the results of CRT in the elderly. Methods Baseline GGT and SA were assessed before CRT device implantation in the elderly(> 70-year-old) patients. The endpoints were:(1) CRT response defined as > 5% left ventricular ejection fraction improvement and no hospitalization for HF or cardiovascular death;(2) hospitalizations;and(3) mortality. Results Eighty of 138(58%) included patients were responders at nine months. Compared to responders, the SA levels were not significantly different(35.1 ± 5.4 vs. 33.6 ± 5.5 g/L, P = 0.103);but the GGT levels, higher(81.6 ± 69.3 vs. 54.7 ± 49.6 U/L, P = 0.013) in non-responders to CRT. GGT level was independently associated with non-response to CRT(P < 0.001, OR = 0.17;95% CI: 0.08–0.38, P < 0.001). GGT cut-off value ≥ 55 U/L was highly predictive of non-response [AUC = 0.65, 64% Sensitivity, 69% Specificity(95% CI: 0.56–0.74)]. GGT ≥ 55 U/L was also associated with higher risk of hospitalization for atrial fibrillation(AF)(95% vs. 83%, P = 0.024). Both SA and GGT had no impact on overall(P = 0.220, P = 0.723) mortality. Conclusions Higher level of GGT is an independent predictor of non-response to CRT in patients over age 70 years and is associated with higher risk of hospitalization for AF. Baseline serum levels of albumin and GGT and have no impact on mortality in elderly patients undergoing CRT.

Cardiac resynchronization therapy in China

Congestive heart failure (HF) is a major and growing public health problem. The therapeutic approach includes non-pharmacological measures, pharmacological therapy,mechanical devices, and surgery. Despite the benefits of optimal pharmacologic therapy, the prognosis is still not ideal. At this time, cardiac resynchronization therapy (CRT)has gained wide acceptance as an alternative treatment for HF patients with conduction delay.1……

Cardiac resynchronization therapy in the elderly heart failure patient

Ms. BP is an 83 year old white female with a long history of congestive heart failure (HF). She is now symptomatic with minimal exertion, has a left ventricular ejection fraction (LVEF) of 20%. Her CHF is due to hypertension (HTN) plus coronary artery disease (CAD) and she is on angiotensin converting enzyme inhibitor (ACEI), furosemide, digoxin,spironolactone, low dose beta blocker and nitrates. Her beta-natriuretic peptide (BNP) in clinic is 3030 pg/ml, heart rate (HR) 100, blood pressure (BP) 89/43.

Predictors of persistence of functional mitral regurgitation after cardiac resynchronization therapy:Review of literature

Functional mitral regurgitation is a common finding among heart failure patients with ischemic and non-ischemic dilated cardiomyopathies.The presence of moderate or severe mitral regurgitation is associated with higher morbidity and mortality.Heart failure patients meeting electrocardiogram and left ventricle function criteria are good candidates for cardiac resynchronization therapy,which may reduce the degree of functional mitral regurgitation in the short and long term,specifically targeting myocardial dyssynchrony and inducing left ventricle reverse remodeling.In this article,we analyze data from the literature about predictors of mitral regurgitation improvement after cardiac resynchronization therapy implantation.

Exercise Training Post Cardiac Resynchronization Therapy Improves Exercise Tolerance and Quality of Life

Background: Cardiac resynchronization therapy (CRT) results in improved morbidity, mortality, symptoms, quality of life (QOL) and exercise capacity, in appropriate chronic heart failure (CHF) patients. Moreover, combined exercise training (ET) and CRT maximize these improvements in these patients. The study evaluated the effect of ET on these patients in terms of QOL, functional class, exercise capacity and left ventricular ejection fraction (LVEF). Results: There were significant improvements in the QOL, functional class, exercise capacity, and LVEF compared with the Control Group. Comparison of both groups confirmed the cumulative effects of ET with CRT. The QOL improved by the end of training in the exercise group (p = 0.001), compared to the Control Group (p = 0.850). NYHA functional class improved significantly in the Exercise Group (p = 0.013). Percent-predicted peak oxygen consumption (VO2 peak) had significantly improved in the trained (p < 0.001) versus the untrained CRT Group (p= 0.596). There was a mean percent rise of the ejection fraction from 39.2 ± 12.86 to 44.40% ± 14.42% in the Exercise Group compared to a non-significant change in the Control Group. Conclusion: ET in resynchronized CHF patients is feasible and further enhances QOL and exercise tolerance in addition to the improvements seen after CRT. The study therefore recommends for the prescription of ET after implantation in order to maximize the expected benefit.

A prospective study to evaluate the efficacy of an intracardiac electrogram-based atrioventricular and interventricular intervals optimization method in cardiac resynchronization therapy

Background Cardiac resynchronization therapy （CRT） with biventricular pacing improves cardiac function,functional capacity and quality of life in selected patients with heart failure.The current study aimed to evaluate the efficacy of the intracardiac electrogram （IEGM）-based optimization method,QuickOptTM,in Chinese patients treated with CRT.Methods Aortic time velocity integrals （AVTI） achieved at the sensed atrioventricular （AV）,paced AV and interventricular （VV） interval settings recommended by both QuickOptTM and standard echocardiographic optimization were measured in 101 patients.Consistency and the strength of the relationship between the two timing cycle optimization methods were assessed by intra-class correlation coefficient （ICC）.Results The ICC showed good agreement and correlation with what the AVTI achieved at the optimal sensed AV （ICC=0.9683 （0.9535-0.9785））,paced AV （ICC=0.9642 （0.9475-0.9757）） and VV （ICC=0.9730 （0.9602-0.9817）） interval settings determined by the two optimization methods.The average time required by echocardiographic optimization and by QuickOptTM were （78.32±32.40） minutes and （1.98±1.64） minutes respectively （P 〈0.0001）.Conclusion The QuickOptTM algorithm provides a quicker,simpler and reliable alternative to the standard method for timing cycle optimization.（ClinicaITrial.gov Reference Number：NCT00918294）

Association of renal function with cardiac reverse remodeling and long-term outcome in heart failure patients following cardiac resynchronization therapy

Background Renal insufficiency （RI） is significantly associated with clinical prognosis in patients with heart failure （HF）,but direct evidences on the relation between renal function and clinical outcome in patients receiving cardiac resynchronization therapy （CRT） are limited.The aim of the current study was to systematically evaluate the association of baseline and 6-month renal function with cardiac reverse remodeling and long-term outcome after CRT.Methods We retrospectively evaluated 190 consecutive patients who underwent CRT at Fuwai Hospital from January 2008 to April 2013.Renal function tests,echocardiographic measurement,and clinical parameters at baseline and after 6 months of CRT were performed.Primary endpoint events included all-cause mortality,cardiac transplantation,and unplanned hospitalizations for HF.Results At baseline,compared with normal renal function or mild RI （estimated glomerular filtration rate （eGFR） 〉-60 ml·min-1·1.73 m-2）,moderate-to-severe RI （eGFR 〈60 ml·min-1·1.73 m-2） exerted a negative influence on cardiac reverse remodeling parameters.At 6-month follow-up,114 （60.0%） patients were classified as responders and showed significant renal function improvement,whereas renal function deteriorated in non-responders and subsequently 41 （25.6%） patients developed worsening renal function （WRF）.During the mean follow-up of （24.3±17.1） months,both patients with baseline eGFR 〈60 ml·min^-1·1.73 m^-2 and those with WRF experienced worse event-free survival （P 〈0.01,respectively）.Conclusions：This analysis identified that baseline eGFR as well as WRF after CRT were found to be independent determinants of the combined endpoints of all-cause mortality and HF-related hospitalizations in CRT recipients.

Initial experiences of maintaining atrioventricular intrinsic conduction during cardiac resynchronization therapy in non-responders

Background Cardiac resynchronization therapy （CRT） is a major breakthrough in therapy for advanced heart failure patients; however, a number of key clinical research questions remain, perhaps most importantly the issue of why apparently suitable patients do not respond to CRT. Methods Seven patients, six males and one female, aged （56.43±6.13） years, all diagnosed with dilated cardiomyopathy, were included in this study. They were all non-responders to CRT who underwent routine optimization postoperatively, and received optimal drug therapy. On the basis of biventricular pacing, titrating various atrioventricular （AV） intervals were performed to get the true fusional QRS complexes composed of biventricular pacing and AV intrinsic conduction. Then, the effects of AV intrinsic conduction during CRT were evaluated. Results On the setting of AV intrinsic conduction during CRT, the true fusional QRS complexes were the narrowest, and all patients showed alleviation of symptoms, improvement of exercise tolerance, life quality and hemodynamic parameters during more than 6 months of follow-up. Conclusions Titrating AV intervals to get the true fusional QRS complexes composed of biventricular pacing and AV intrinsic conduction will be beneficial for non-responders to CRT. Maintaining AV intrinsic conduction during CRT may decrease the rates of non-resoonders to CRT.

Short-term effect of cardiac resynchronization therapy in patients with ischaemic or nonischaemic cardiomyopathy

Background Patients with heart failure were candidates for cardiac resynchronization therapy （CRT） regardless of underlying aetiology. This study observed the effect of CRT in patients with ischaemic or nonischaemic cardiomyopathy. Methods One hundred and forty-two patients with refractory chronic heart failure and left bundle branch block received cardiac resynchronization therapy, 91 men and 51 women, average age 60 years. Left ventricular ejection fraction （LVEF） was severely depressed （mean 29%）, left ventricular end diastolic diameter （LVEDD） enlarged （mean 72 mm） and QRS width was lengthened （mean 147 ms）. Ninety-eight had nonischaemic cardiomyopathy and 44 had ischaemic cardiomyopathy. Results After cardiac resynchronization therapy, the heart function was significantly improved. The mean LVEF increased from 29% to 36% after pacing. In patients with nonischaemic cardiomyopathy, the LVEF was improved from 28% to 37%, and in patients with ischaemic cardiomyopathy, the LVEF was improved from 30% to 36%. No significant difference of the improvement was found between the two groups （P〉0.05）. Conclusions Cardiac resynchronization therapy could significantly improve cardiac function in patients with chronic heart failure regardless of the underlying heart disease.

Improvement of P-wave dispersion is associated with a lower incidence of atrial fibrillation after cardiac resynchronization therapy

Background P-wave dispersion （PWD） is a useful predictor of paroxysmal atrial fibrillation （AF）. The effect of cardiac resynchronization therapy （CRT） on PWD and the prognostic implications of the improvement in PWD remain undefined. The aim of the study was to explore the clinical significance of the improvement of PWD after CRT. Methods Electrocardiographic studies were performed before and three months after CRT in 81 patients （57 men and 24 women; age （60.5±11.2） years） with standard CRT indication but no history of AF. A significant improvement of PWD （PWD responder） was defined as a relative decrease 〉20% from baseline PWD. The primary endpoints were new-onset AF detected by electrocardiogram （ECG） or CRT. Results After （30.6±7.5） months of follow-up, PWD responders （n=43） had a significantly lower incidence of AF than did PWD nonresponders, 12% vs. 29% （P 〈0.001）. In Cox proportional hazard analysis, PWD responders was the only predictor of lower risk of new-onset AF （HR 0.33, 95% confidence interval 0.12-0.96, P=0.033）. Conclusion Improvement of P-wave dispersion after CRT was associated with a lower incidence of AF, which may be related to the significant improvement in left ventricular systolic function and the reverse modeling of the left atrium.

Decrease of plasma N-terminal pro p-type natriuretic peptide as a predictor of clinical improvement after cardiac resynchronization therapy for heart failure

Background N-terminal pro β-type natriuretic peptide （NT pro BNP） has been shown to predict the prognosis and could guide the treatment of heart failure. We aimed to investigate the values of NT pro BNP in predicting the clinical response to cardiac resynchronization therapy （CRT）. Methods A total of 44 patients with chronic heart failure （34 male and 10 female, mean age of （58±13） years, New York Heart Association （NYHA） class 3.3±0.5, QRS duration （150±14） milliseconds） who underwent successful implantation of a CRT system were enrolled in this study. Pharmacotherapy remained stable during the first 3 months of follow-up. Plasma levels of NT pro BNP were evaluated before and 3 months after implantation. Clinical, echocardiographic and exercise parameters were monitored at each clinical visit after CRT implantation. Receiver operating characteristic analysis and a paired ttest were performed to analyze the data. Results After a mean of （16.3±5.5） months of follow-up, 11 nonresponders were identified. CRT resulted in a significant reduction in NT pro BNP （（1.70±1.28） vs （1.07±0.88） pmol/ml, P 〈0.001） in responders. Percentage change in NT pro BNP level （△BNP%） was a statistically significant predictor of long term clinical improvement at 3 months of follow-up. Conclusions △BNP% from baseline to 3 months of follow-up is a predictor of long term response to CRT. NT pro BNP may be a simple method for monitoring the effects of CRT.

Optimized cardiac resynchronization therapy in patients with congestive heart failure

Heart failure was a major and increasing public health problem, with an almost ＂epidemic＂ increase in the number of patients. Despite recent advances in pharmacotherapy, the prognosis remains poor. Cardiac resynchronization therapy （CRT）, by pacing right and left ventricles, has been proved to improve symptoms and reduce mortality for heart failure patients with cardiac dyssynchrony, However, 20% to 30% of patients did not respond to CRT. The good cardiac synchronicity before CRT and the remaining atrioventficular, inter- and intra-ventricular dyssynchrony after CRT may explain the non-response. New echocardiographic techniques, and in particular tissue Doppler imaging （TDI） analysis, has been proved to be a helpful tool in evaluating cardiac dyssynchrony, as well as in assessing the degree of cardiac resynchronization after biventricular device implantation. So, in this study, we optimized the pacing parameters to determine whether echo-guided optimizing of AV/VV delays would enhance the effect of CRT on cardiac function and synchronicity.

Potential predictors of non-response and super-response to cardiac resynchronization therapy

Background Although cardiac resynchronization therapy （CRT） is already an established treatment, the characteristics of patients who have an excellent response to CRT and those who get no benefit remain to be determined. The purpose of this study was to search for potential predictors of both non-response and super-response to CRT.Methods Seventy-six consecutive patients who received CRT treatment were divided into group A （non-responders）,group C （super-responders） and group B （responders exclusive of super-responders）. Student＇s t test, Mann-Whitney test, Logistic regression and receiver operating characteristic curve were employed to identify potential predictors among the patients＇ demographic characteristics, clinical features, several electrocardiographic parameters before and after CRT implantation, and their pre-implant echocardiographic parameters.Results Group A had the lowest 3-month left ventricular ejection fraction （LVEF）. Group C had the smallest pre-implant left ventricular end-diastolic dimension （LVEDD）, the shortest post-implant QRS duration, the smallest 3-month LVEDD and the highest 3-month LVEF. In addition, there was a trend of gradual change in percent of left bundle branch block,severity of pre-implant mitral regurgitation, pre-implant QRS dispersion, post-implant QRS duration as well as post-implant QRS dispersion from group A to group B and from group B to group C. Multivariable Logistic analysis revealed that only pre-implant LVEDD could predict CRT super-response. A pre-implant LVEDD of 68.5 mm was the cut-off value that identified super-responders with 87.5% sensitivity and 79.7% specificity. A pre-implant LVEDD of 62.5mm identified super-responders with 50.0% sensitivity and 89.8% specificity.Conclusions Predictors of a CRT non-response remain unclear at present. But it is credible that patients with a smaller left ventricle would have a better chance to become super-responders to CRT.

Complications of cardiac resynchronization therapy in patients with congestive heart failure

Background Previous clinical studies have suggested that patients with congestive heart failure and intraventricular conduction delay could benefit from cardiac resynchronization therapy （CRT）. Implantation of left ventricular lead is a complex procedure with some potential for complications. This study was conducted to analyse the complications of CRT in patients with congestive heart failure.Methods Totally 117 patients, 86 males and 31 females, mean age of 53 years, with congestive heart failure and intraventricular conduction delaywere enrolled in this study. Venography was performed on all patients. Different types of coronary sinus leads were used to pace the left ventricle.Results Left ventricular lead was attempted to implant through coronary sinus for all the 117 patients and was successfully implanted in 111 patients. The success rate was 94.9%. Main complications rate was 6.8%, including coronary sinus dissection in 4 patients, phrenic nerve stimulation required lead repositioning in 2 patients and lead dislodgement in 2 patients.Conclusions It is feasible and safe to pace left ventricle through coronary sinus. However, there are some procedural complications.

Echocardiographic mapping of left ventricular resynchronization during cardiac resynchronization therapy procedures

Background Cardiac resynchronization therapy （CRT） is an effective electrical therapy for patients with moderate to severe heart failure and cardiac dyssynchrony. This study aimed to investigate the degree of acute left ventricular （LV） resynchronization with biventricular pacing （BVP） at different LV sites and to examine the feasibility of performing transthoracic echocardiography （TTE） to quantify acute LV resynchronization during CRT procedure. Methods Fourteen patients with NYHA Class Ⅲ-Ⅳ heart failure, LV ejection fraction 〈35%, QRS duration 〉120 ms and septal-lateral delay （SLD） 〉60 ms on tissue Doppler imaging （TDI）, underwent CRT implant. TDI was obtained from three apical views during BVP at each accessible LV site and SLD during BVP was derived. Synchronicity gain index （Sg） by SLD was defined as （I＋（SLD at baseline - SLD at BVP）/SLD at baseline）. Results Seventy-two sites were studied. Positive resynchronization （R＋, Sg〉1） was found in 42 （58%） sites. R＋ was more likely in posterior or lateral than anterior LV sites （66% vs. 36%, P 〈0.001）. Concordance of empirical LV lead implantation sites and sites with R＋ was 50% （7/14）. Conclusions The degree of acute LV resynchronizaUon by BVP depends on LV lead location and empirical implantation of LV lead results in only 50% concordance with R＋. Performing l-rE during CRT implantation is feasible to identify LV sites with positive resynchronization.

Atrioventricular intrinsic conduction and cardiac resynchronization therapy

Cardiac resynchronization therapy （CRT） is a major breakthrough in therapy for patients with advanced congestive heart failure, however, a number of key clinical research questions remain, perhaps most importantly the issue of why apparently suitable patients do not respond to CRT. These issues are also relevant to patients who do respond to CRT as potentially their response might be further increased. Though patients do not respond to CRT because of many known postulated reasons, we review the importance of maintaining atrioventricular intrinsic conduction during CRT in this paper, which maybe is one of methods to reduce the rates of non-response to CRT.

Results of transvenous lead extraction of coronary sinus leads in patients with cardiac resynchronization therapy

Background The need for transvenous lead extraction procedures of coronary sinus （CS） leads is increasing due to rising numbers of implanted cardiac resynchronization therapy devices during the past decade. Methods From January 2009 to June 2013, 27 CS leads were scheduled for extraction in 27 patients （mean age （63.1±14.6） years）. Indications for lead extraction were infection in 13 and lead dysfunction in 14 cases. Isolated extraction of CS leads was performed in eight, extraction of multiple leads in 19 cases. Among leads with an implant time of 〉12 months （n=19） mean implant duration （MID） was （46.4±15.2） （12-76） months. Groups were formed depending on infectious or non-infectious indications （INF vs. Non-INF）, and the use or non-use of extraction tools （ET1 vs. ET0）. Results Among patients with an implant duration of 〉12 months, complete procedural success was 94.7% and clinical success 100%. Operative mortality was zero. In the INF versus NON-INF groups complete procedural success （100% vs. 91.7%, P=0.43）, mean number of required extraction tools （0.7 （0-2） vs. 0.9 （0-3）, P=0.65） and MID （49.1±15.0 vs. 44.7±15.8, P=0.83） did not differ significantly. Comparing the groups ET1 and ET0 showed no significant differences in complications （n=l vs. n=l, P=-0.81） and MID （47.0±17.5 vs. 45.5±12.6, P=0.71）. Conclusions In specialized centers transvenous lead extraction of coronary sinus leads with a mean implant duration of almost four years can be performed safely and effectively. Neither non-infectious indications nor the use of extraction tools negatively affected the outcome of the procedure.

Presence of notched QRS on paced electrocardiographs as a predictor of poor response to cardiac resynchronization therapy

Background Cardiac resynchronization therapy （CRT） on patients with advanced and refractory heart failure has made remarkable progress.Clinically,notched QRS （nQRS） is commonly seen on electrocardiographs （ECGs） with bundle branch block morphology and on paced ECGs after implantation of a CRT device,which may reflect the heterogeneity of ventricular myocardial depolarization and electrical activity.The aim of this study was to determine whether patients with more nQRS myocardial segments on paced ECGs had a worse response to CRT than patients with fewer nQRS myocardial segments.Methods We prospectively enrolled 56 patients of CRT with chronic heart failure from People＇s Hospital affiliated to Peking University from January 2007 to October 2013.Based on nQRS segments on ECGs before CRT,we allocated them to two groups：fewer nQRS （〈2） myocardial segments （lateral,inferior,anterior segments） group （F-nQRS,G1,n=23） and more nQRS （≥2） myocardial segments group （M-nQRS,G2,n=33）.Then according to nQRS segments on ECGs after CRT,we divided them into two groups similarly：fewer nQRS （〈2） myocardial segments group （G3,n=24） and more nQRS （≥2） myocardial segments group （G4,n=32）.This study was approved by the ethics committee of People＇s Hospital.Results At 6 months in the baseline-ECG group,there was a greater absolute increase in left ventricular ejection fraction （LVEF） in G2 than in G1 （（11.5±8.9）% vs.（5.5±10.4）%,P=0.023）,with the incidence of nonresponse lower in G2than in G1 （9.1% vs.39.1%,P=0.018）.In the paced-ECG group,the absolute increase in LVEF was less in G4 than in G3 （（6.4±8.8）% vs.（12.5±10.4）%,P=0.024） and the incidence of nonresponse was higher in G4 than in G3 （31.3% vs.8.3%,P=0.039）.Multivariate analysis showed that fewer nQRS （〈2） myocardial segments on paced ECGs （odds ratio 13.920） was a predictor of positive response to CRT.Conclusion nQRS ≥2 myocardial segments （lateral,inferior,anterior） on paced ECGs may predict a poor response to CRT.