Cardiac resynchronization therapy for heart failure induced by left bundle branch block after transcatheter closure of ventricular septal defect

A 54-year-old female patient with congenital heart disease had a persistent complete left bundle branch block three months after closure by an Amplatzer ventricular septal defect occluder. Nine months later, the patient suffered from chest distress, palpitation, and sweating at daily activities, and her 6-min walk distance decreased significantly （155 m）. Her echocardiography showed increased left ventricular end-diastolic diameter with left ventricular ejection fraction of 37%. Her symptoms reduced significantly one week after received cardiac resynchronization therapy. She had no symptoms at daily activities, and her echo showed left ventricular ejection fraction of 46%and 53%. Moreover, left ventricular end-diastolic diameter decreased 6 and 10 months after cardiac resynchronization therapy, and 6-min walk dis-tance remarkably increased. This case demonstrated that persistent complete left bundle branch block for nine months after transcatheter closure with ventricular septal defect Amplatzer occluder could lead to left ventricular enlargement and a significant decrease in left ventricular systolic function. Cardiac resynchronization therapy decreased left ventricular end-diastolic diameter and increased left ventricular ejection fraction, thereby improving the patient’s heart functions.

Delayed spontaneous reversibility of left bundle branch block in non-ischemic cardiomyopathy: a case report

Left bundle branch block(LBBB)causes a delay in left ventricular contraction with an unsynchronized ventricular systole.LBBB is an independent determinant of morbi-mortality mainly when associated with cardiomyopathy and left ventricular dysfunction.[1] LBBB due to non-ischemic cardiomyopathy is considered non-reversible.Such irreversibility occurs because LBBB and cardiomyopathy act in a synergic manner in order to maintain both situations.However,there are a few reports in the literature showing that some patients have had an improvement in cardiac function with normalization of QRS and have experienced a reverse remodelling with pharmacological therapy only.[2–4]

Exercise-induced left bundle branch block: an infrequent phenomenon: Report of two cases

Exercise-induced left bundle branch block(EI-LBBB)is infrequent phenomenon.We present two patients with angina pectoris who developed EI-LBBB during exercise tolerance test.The first patient with typical angina pectoris had significant obstructive coronary artery disease(CAD)requiring percutaneous coronary intervention of multiple lesions including placement of drug eluting stents.The second patient had atypical chest pain without signs of CAD at all.EI-LBBB occurred at a heart rate of 80 bpm and 141 bpm in the first and second patient,respectively.EI-LBBB remained visible through the test till the recovery period in the first patient at a heart rate of 83 bpm and disappeared at 96bpm in the second patient.Both patients with this infrequent phenomenon are discussed and the literature is reviewed.

Differential diagnosis of tachycardia with a typical left bundle branch block morphology

The evaluation of wide QRS complex tachycardias (WCT)remains a common dilemma for clinicians.Numerous algorithms exist to aid in arriving at the correct diagnosis.Unfortunately,these algorithms are difficult to remember,and overreliance on them may prevent cardiologists from understanding the mechanisms underlying these arrhythmias.One distinct subcategory of WCTs are those that present with a"typical"or"classic" left bundle branch block pattern.These tachycardias may be supraventricular or ventricular in origin and arise from functional or fixed aberrancy,bystander or participating atriofascicular pre-excitation,and bundle branch reentry.This review will describe these arrhythmias,illustrate their mechanisms,and discuss their clinical features and treatment strategies.

Cardiovascular Risk in Young Workers with Left Bundle Branch Block

Aims: Left bundle branch block (LBBB) is generally associated with a poorer prognosis in comparison to normal intraventricular conduction, but also in comparison to right bundle branch block which is generally considered to be benign in the absence of an underlying cardiac disorder like congenital heart disease. In this paper we evaluate the presence of possible cardiovascular pathology in a group of nurses with a low level of cardiovascular risk factors and left bundle branch block (LBBB). Methods: During the period 2009-2013, 356 nurses (mean age: 32.6 ± 11 yr) were admitted to the department of Occupational Medicine of Second University of Naples. Of these, 13 had LBBB. The evaluation of these patients has included an electrocardiogram (ECG), echocardiography, 24-h ambulatory Holter monitoring (ECG Holter), and exercise testing. Subsequently, in patients with LBBB, multislice computed coronary angiography (MSCT) has been considered. Results and Conclusion: Only in one patient we found a significant stenosis in the middle tract of left anterior descending artery. Coronary artery disease remains difficult to diagnose in some ECG findings such as acquired LBBB. For this reason, a preventive diagnose with newly developed diagnostic methods such as the multislice computed coronary angiography (MSCT) must try to account by the clinician in order to ruling out coronary artery disease (CAD) in workers with LBBB and low cardiovascular risk.

Prognostic implication of the coronary microvascular dysfunction in patients with isolated left bundle branch block

The present study aims to determine the influence of microvascular dysfunction (MVD) in the prognosis of patients presenting isolated left bundle branch block (LBBB). Methods: We studied 30 patients (pts), 22 males, 8 females, mean age 57 ± 4 years, with isolated LBBB, with a mean follow up of 48 ± 6 months. The control group consisted of 20 healthy individuals, 12 males, mean age 52 ± 10 years. Both groups were screened for cardiovascular risk factors (RF);they also had an echocardiogram and Coronary CT Scan, ruling out both structural heart disease and obstructive lesions of the epicardial coronary arteries. A myocardial perfusion study was then performed, with two groups emerging according to these results: Group A, 8 pts (26%), with reversible perfusion defects, in which the diagnosis of MVD was suspected, and Group B, 22 pts (74%), with either normal perfusion or minor septal/apical reversible defects (related to LBBB). All Group A pts, and 9 of the Group B pts, underwent coronary arteriography, with intracoronary acetylcholine and nitroglycerine infusion, thus evaluating vasomotor response as endothelium dependent (acetylcholine) or endothelium independent (nitroglycerine). During follow up, we reviewed functional class, 12 lead ECG and echocardiogram on a yearly basis. Results: All Group A patients had an abnormal acetylcholine response;only three of them had abnormal response to nitroglycerine infusion, suggesting endothelium dependent MVD. Of those in Group B, only one patient had abnormal acetylcholine response. At the end of the follow up period, 3 pts (37%) in Group A, showed functional class decrease vs 5 pts (22%) of those in Group B. In Group A, a significant increase of End Diastolic Left Ventricle Diameter (EDLVD) was found (51.6 ± 3.6 vs 59.3 ± 6.8 mm;p < 0.05) with significant decrease in LVEF (62 ± 4.8 vs 46% ± 3.7%, p variation. In neither group major complications (death, heart failure admissions) were found. Conclusion: We confirm the association between MVD and a worse clinical prognosis in isolated LBBB patients. Repeated ischemia and myocardial fibrosis are highlighted as possible physiopathological mechanisms, precluding a progressive left ventricular function decrease, with a higher mortality and arrhythmia risk. Endothelial function preserving strategies, both preventive and therapeutic, might be useful in improving LBBB with MVD patient’s prognosis.

Left bundle branch block and myocardial infarction, a diagnosis not always easy: Our experience and review of literature

The occurrence of left bundle branch block (LBBB) is quite common in clinical practice. The changes in cardiac repolarization, caused by this disorder of electric conduction, may mask the presence of an acute myocardial infarction (AMI), delaying the diagnostic-therapeutic iter, with an important impact on prognosis. We describe the case of a woman of 59 years with LBBB, came to our observation for a constrictive chest pain associated with dyspnea. The diagnostic workup for suspected acute coronary syndrome (ACS), initially conducted only on the analysis of the electrocardiogram (negative TnI at entry), showed the presence of coronary arteries free of stenosis. However, the diagnostic confirmation of AMI was completed after the rise of cardiac markers and the electrocardiographic changes. This case confirm the difficulty about the diagnosis of AMI in patients with LBBB and stresses, however, as the use of some criteria proposed in the literature [1-3] can guide to its identification, directing patient to an appropriate treatment.

Clinical Profile of the Patients with Newly Detected Left Bundle Branch Block in the Outpatient Department

Objective: The purpose of this study was to evaluate cardiac features associated with newly detected left bundle branch block (LBBB) in the outpatient department. Methods: A total of 57 patients with LBBB pattern were evaluated using electrocardiography (ECG). Patients were assessed based on their sex, age, detailed history, and cardiovascular symptoms. Cardiac investigations including ECG and echocardiography were performed. Results:The study included 30 (52.6%) males and 27 (47.5%) females, aged between 35 and 80 years. Dyspnoea (35.1%) and chest pain (22.8%) were the most common symptoms. 54.4% were hypertensive and 17.5% were diabetics. 28% had Left ventricular systolic dysfunction, and 24.5% had aortic valve disease. Left ventricular hypertrophy without any other structural heart disease was present in 28% of the patients. Only 24.5% patients presented with LBBB had a structurally normal heart in echocardiography. Myocardial performance index in echocardiography was abnormal in LBBB irrespective of the presence of structural heart disease. Conclusion: The prevalence of LBBB was found to increase with age and had slight male preponderance. Dyspnoea on effort was the most common presenting complaint, followed by chest pain and incidental detection of ECG abnormality. Most of the patients were hypertensive. Only 24.5% patients with LBBB had a structurally normal heart. MPI was abnormally high in the presence of LBBB despite having a normal left ventricular ejection fraction.

Can regadenoson pharmacologic SPECT be performed effectively in patients with left bundle branch block or paced rhythm patients? A retrospective comparison to adenosine SPECT

Purpose: Regadenoson (REG) is currently becoming the stress agent of choice in patients undergoing pharmacologic single photon emission computed tomography (SPECT). However, in patients with left bundle branch block (LBBB) and ventricular paced rhythm (VPR), hesitation exists amongst clinicians to use REG-SPECT due to the concern that the increased heart rate could cause false positive SPECT results. We sought to evaluate the comparability of A-SPECT and REG-SPECT in patients with LBBB and VPR. Methods: Retrospective study of 30 patients who served as their own controls. All 30 patients who underwent REG-SPECT (Grp 1) were compared to their prior A-SPECT (Grp 2) done within two years prior to REG-SPECT. Heart rate (HR) and blood pressure (BP) parameters, ECG, stress perfusion and gated variables, SPECT ischemia, and side-effects were evaluated. Statistical significance was set at P < 0.05. Results: Grp 1 and Grp 2 were comparable in hemodynamic parameters with increase in HR and decrease in systolic and diastolic BP with administration of adenosine and REG stress agents. However, there were no significant differences found in hemodynamic parameters and II degree AV block between the groups. All normal A-SPECT were found to be normal with REG-SPECT. No differences could be found between the two groups among SPECT parameters. Muscle pain was significantly higher in REG (10.0% vs. 0.0%, P = 0.083) and so was the use of aminophylline (16.7% vs. 0.0%, P = 0.025) to relieve the side-effect. Conclusion: REG-SPECT can be administered in patients with LBBB and VPR patients based on favorable and comparable hemodynamic responses and arrhythmia occurrences to A-SPECT. REG-SPECT can also be used for adequate interpretation of presence or absence of SPECT ischemia particularly in the LAD territory without any concern for false positive perfusion defects.

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.

Clinical efficacy and predictor of cardiac resynchronization therapy on left bundle branch block-associated heart dysfunction

Background Left bundle branch block （LBBB） results in an altered pattern of left ventricular （LV） activation and subsequent contraction. Cardiac synchrony and cardiac function are deteriorated by LBBB. However, the effect of LBBB history on progressive heart dysfunction and clinical efficacy of cardiac resynchronization therapy （CRT） in such patients are not clear. In this study we explore the clinical efficacy and predictor of cardiac resynchronization therapy in LBBB heart dysfunction. Methods Twenty-seven LBBB patients with severe heart failure were treated with CRT. Twenty-six LBBB patients without CRT served as control. During 6 months follow-up, ECG, plasma NT-proBNP and echocardiogram indexes were measured. Results Compared with baseline, NYHA functional class of 23 patients （85.2%） was improved in CRT group. Compared with baseline and control, QRS duration （QRSd） was significantly more narrow （P = 0.023, P = 0.019）, NT-proBNP was significantly lower （P = 0.011,P = 0.009）, ventricular septal to left ventricular posterior wall delay time and left ventricular dyssynchrony index （Ts-SD） were significantly worse （P 〈 0.05）; left ventricular ejection fraction, left ventricular end-systolic volume, mitral regurgitation area were significantly improved in CRT group （P 〈 0.05）. when the LBBB history was I〉 2 years and QRSd I〉 155 ms, the sensitivity and specificity of CRT super-response were 53.4% and 85.6% respectively. Conclusions CRT can improve the synchronization and hemodynamic of LBBB patients with heart dysfunction, the LBBB history I〉 2 years and QRSd I〉 155 ms are one of the CRT super-response predictors.

Cardioprotective effects of trimetazidine on patients with dilated cardiomyopathy and left bundle branch block

Background The effects of trimetazidine on patients with dilated cardiomyopathy（DCM） and left bundle branch block（LBBB） are not clear. Methods Sixty consecutive patients with DCM, LBBB and heart dysfunction（35% ≤ LVEF ≤ 45%） were randomly allocated to heart failure therapy plus trimetazidine group（20 mg three times a day; 30 patients） or heart failure therapy alone group（30 patients）. During follow-up of 6months, QRS morphology, plasma NT-proBNP, 6-minute walk test（6MWT） and echocardiographic indexes were measured. Results At the 6th month, a significant functional improvement was noted in patients receiving trimetazidine added to heart failure treatment. In patients from the trimetazidine group, an increase of left ventricular ejection fraction（LVEF） was noted（from 38 ± 5.5% to 47 ± 7.1%, P = 0.020）. The increase of LVEF in the trimetazidine group was associated with a more significant reduction of the left ventricular endsystolic diameter（LVESD） compared with the control group at 6-month follow-up. The NT-pro BNP levels decreased significantly in the trimetazidine group（3.11 ± 0.47 at baseline and 2.77 ± 0.45 at 6-month followup, P 〈 0.01） and the 6MWT increased significantly in the trimetazidine group（325 ± 44 m at baseline and419 ± 56 m at 6-month follow-up, P 〈 0.01）. The differences in NT-pro BNP levels（2.77 ± 0.45 vs 2.96 ±0.46, P = 0.036） and 6MWT（419 ± 56 m vs 366 ± 54 m, P = 0.032） between the two groups were significant at 6-month follow-up. Conclusions Trimetazidine can improve LV function caused by DCM and LBBB. The positive effects of trimetazidine on LV function are especially evident in patients with optimization of drug therapy for heart failure, which strongly suggests an additive effect of these therapy modalities.

Intermittent Left Bundle Branch Block and Myocardial Ischemia in Patient Without Coronary Artery Stenosis:A Case Report

Left bundle branch block （ LBBB ）, traditionally viewed as an electrophysiologic abnormality, is increasingly recognized for its effects on hemodynamics and patient＇s prognosis^[1]. Exercise nuclear studies frequently show reversible perfusion defects in the absence of obstructive coronary artery disease^[2] and some patients with intermittent LBBB develop angina coincident with the onset of LBBB^[3]. We report a case of intermittent LBBB with abnormal stress technetium 99m TC single-photon emission computed tomography （SPECT） study and normal coronary artery angiography.

Inadvertent Lead Malposition in the Left Ventricle during Permanent Ventricular Pacing about One Case

Inadvertent Lead Malposition in Left Ventricle is a rare and underdiagnosed incident, which may occur during implantation of cardiac electronic devices and may remain asymptomatic. We reported the case of a 71-year-old man who was implanted with a ventricular single-chamber pacemaker for a slow atrial fibrillation with syncope and whose routine transthoracic echocardiography 23 months after implantation displayed a malposition of the pacemaker lead into the Left Ventricle through a patent foramen oval. The patient was asymptomatic. The electrocardiogram showed right bundle branch block QRS-paced morphology with a positive QRS pattern in V1, a median paced QRS axis on the frontal plane at -120°, a Precordial transition on V5. At the lateral Chest X-ray the lead curved backwards to the spine. Given the age of this old patient who already received oral anticoagulant for Atrial Fibrillation and the Lead malposition discovered 23 months after pacemaker’s implantation, we decided to maintain the lead in LV and continue anticoagulation.

Pacemaker post transcatheter aortic valve replacement:A multifactorial risk?

Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have at least as much impact on the final need for a permanent pacemaker and potentially on the pacing rate.In this regard,long-term follow-up and understanding of the impact of long-term stimulation is of utmost importance.

左束支区域起搏对房室传导阻滞患者术后新发房性心律失常的影响

目的探讨左束支区域起搏(left bundle branch area pacing,LBBaP)对房室传导阻滞(AVB)患者术后新发心房颤动(new-onset atrial fibrillation,NOAF)和心房高频事件(atrial high rate episodes,AHREs)的影响。方法回顾性纳入84例行起搏治疗的三度房室传导阻滞(ⅢAVB)患者,根据心室电极位置分为LBBaP组(n=42)和右室间隔部起搏(RVSP)组(n=42)。比较两组患者术前术后QRS波时限(QRSd)、心室起搏参数,并发症、脑卒中事件和NOAF、AHREs发生率。结果(1)LBBaP组术后NOAF、AHREs发生率均低于RVSP组(P<0.05)。(2)LBBaP组的p-QRSd短于RVSP组(P<0.05)。(3)两组患者心室起搏参数、并发症及脑卒中事件发生率之间差异无统计学意义(P>0.05)。结论相对于右室起搏,LBBaP术后AHREs、NOAF的发生率较低,可改善患者预后。

左束支区域起搏在改善右束支阻滞、射血分数降低患者心功能中的应用效果

目的探究左束支区域起搏(LBBaP)在改善右束支阻滞(RBBB)、射血分数降低(LVEF)≤35%患者心电图及心功能改善的效果。方法选取2020年2月到2022年8月期间九江市第一人民医院心血管内科的80例RBBB且LVEF≤35%患者作为研究对象,采用随机数字表法将其分为对照组(40例)及试验组(40例)。对照组给予双室起搏(Bi-V),试验组给予LBBaP。比较两组患者治疗前后左室舒张末径(LVDED)、左室射血分数(LVEF)、6 min步行距离(6MWD)、NN间期标准差(SDNN)、相邻NN间期之差的均方根值(rMSSD)、每5分钟NN间期均值的标准差(SDANN)、ST-T波改变情况、心力衰竭再入院率、死亡发生率、主要并发症(心脏穿孔、心包积血、恶性心律失常、心源性猝死和急性心肌梗死)。结果两组患者治疗前LVDED、LVEF、6MWD比较,差异无统计学意义(P>0.05)。两组患者治疗后LVDED低于本组治疗前,LVEF高于本组治疗前,6MWD长于本组治疗前,差异有统计学意义(P<0.05)。试验组治疗后低于对照组,LVEF高于对照组,6MWD长于对照组,差异有统计学意义(P<0.05)。试验组的ST-T波改变率高于对照组,SDNN、rMSSD、SDANN均低于对照组,差异有统计学意义(P<0.05)。试验组心力衰竭再入院率、并发症发生率、死亡率均低于对照组,差异有统计学意义(P<0.05)。结论左束支区域起搏可有效改善心功能及心电图指标,降低心力衰竭再入院率、并发症发生率、死亡率,值得推广。

经导管主动脉瓣置换术后新发持续完全性左束支传导阻滞的危险因素及短期预后分析

目的 分析经导管主动脉瓣置换术(transcatheter aortic valve replacement, TAVR)术后新发持续完全性左束支传导阻滞(complete left bundle branch block, cLBBB)的相关危险因素及cLBBB对短期预后的影响。方法 选取2019年1月至2022年8月在青岛市市立医院心脏中心经股动脉行TAVR的78例主动脉瓣膜狭窄病人为研究对象,根据TAVR术后至出院时是否发生cLBBB分为新发持续性cLBBB组(n=26)和非左束支传导阻滞(LBBB)组(n=52)。收集并比较2组病人的基线资料、生化检查指标、CT等影像检查结果、瓣膜和手术相关数据,以及6个月后病人的预后情况。采用多因素Logistic回归分析TAVR术后新发持续性cLBBB的危险因素。结果 78例病人中,26例(33.3%)在TAVR术后出现持续性cLBBB。Logistic回归分析显示,术前存在的不完全性LBBB(OR=7.609, 95%CI:1.051~55.066)、植入瓣膜过大率≥17.25%(OR=1.096, 95%CI:1.017~1.181)及无窦侧瓣膜植入深度≥4.96 mm(OR=3.633, 95%CI:1.363~9.686)是TAVR术后新发持续性cLBBB的独立危险因素。术后第6个月随访时,新发持续性cLBBB组有更高的心力衰竭再住院率(16.0%比1.9%,P=0.02)。结论 术前不完全性LBBB、较高的植入瓣膜过大率及冠脉无窦侧瓣膜植入过深是影响TAVR术后持续性cLBBB发生的危险因素。新发cLBBB病人有更高的心力衰竭再住院风险。

左束支起搏和右室心尖部起搏在老年房室传导阻滞患者中的临床疗效比较

目的比较左束支起搏(left bundle branch pacing,LBBP)和右室心尖部起搏(right ventricular apical pacing,RVAP)治疗老年房室传导阻滞(atrioventricular block,AVB)患者的临床效果。方法回顾性分析2016年1月—2021年6月因AVB于同济大学附属第十人民医院行永久起搏器植入术256例患者(≥65岁)的临床资料,根据起搏方式将患者分为RVAP组(n=121)和LBBP组(n=135)。比较两组起搏方式的临床疗效。结果两组患者基线资料均无明显统计学差异。两组患者的起搏参数(阈值、感知和阻抗)在术中、术后7 d、术后1年差异均无统计学意义(均P>0.05),但LBBP组患者术后QRS波群时限明显缩短(均P<0.001)。术后1年随访中,与RVAP组相比,LBBP组起搏术式显著改善患者心功能,如左室射血分数、左心室舒张末期内径、NT-proBNP表达水平(均P<0.05)。此外,LBBP组和RVAP组相比,并发症发生率和起搏器依赖患者比例无显著差异(均P>0.05),但LBBP患者术后1年内再住院率显著降低(P=0.004)。进一步行Logistic回归分析发现LBBP起搏术式与老年AVB患者的再住院率有关(全部进入模式P=0.014,向前逐步回归模式P=0.010)。Kaplan-Meier累积事件曲线的比较显示RVAP和LBBP的累积再住院率有显著统计学差异(P=0.003)。ROC曲线分析也揭示了不同起搏术式对老年AVB患者的再住院率有预测价值(P=0.011,AUC=0.703,灵敏度=0.857,特异度=0.550)。结论与传统RVAP相比,LBBP起搏术式治疗老年AVB患者具有更好的安全性和稳定性,可有效改善患者心功能,降低患者再住院率。

Cardiac resynchronization therapy: Dire need for targeted left ventricular lead placement and optimal device programming

Cardiac resynchronization therapy(CRT) effected via biventricular pacing has been established as prime therapy for heart failure patients of New York Heart Association functional class Ⅱ, Ⅲ and ambulatory Ⅳ, reduced left ventricular(LV) function, and a widened QRS complex. CRT has been shown to improve symptoms, LV function, hospitalization rates, and survival. In order to maximize the benefit from CRT and reduce the number of non-responders, consideration should be given to target the optimal site for LV lead implantation away from myocardial scar and close to the latest LV site activation; and also to appropriately program the device paying particular attention to optimal atrioventricular and interventricular intervals. We herein review current data related to both optimal LV lead placement and device programming and their effects on CRT clinical outcomes.