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.     

The benefit of cardiac resynchronization therapy and QRS duration: a meta-analysis

CRT and QRS Duration . Background: Cardiac resynchronization therapy (CRT) improves outcomes in patients with heart failure (HF) because of reduced left ventricular systolic function and a wide QRS complex. Whether this benefit is consistent across all degrees of QRS widening is unclear. We performed a meta‐analysis of randomized clinical trials to evaluate the impact of QRS duration on the efficacy of CRT. Methods and Results: We searched MEDLINE and EMBASE databases for studies evaluating the efficacy of CRT in patients with HF. Only trials that reported subgroup data according to QRS duration were included. Hazard ratios (HR) with 95% confidence interval (CI) were calculated using a random effects model. Five trials involving 6,501 patients (4,437 with QRS ≥ 150 ms and 2,064 with QRS < 150 ms) were included. Three trials, enrolling patients with mild to moderate HF, compared CRT‐implantable cardioverter defibrillator with CRT, whereas CRT versus medical therapy was compared in the other 2 trials, which included patients with advanced HF. Based on the pooled estimate across the 5 studies, CRT significantly decreased the primary endpoint of death or hospitalization for HF in patients with QRS ≥ 150 ms (HR = 0.58, 95% CI: 0.50–0.68; P < 0.00001), but not in patients with QRS < 150 ms (HR = 0.95, 95% CI: 0.83–1.10; P = 0.51). These results were consistent across all degrees of HF severity. Conclusions: The benefit of CRT seems to be dependent on QRS duration. Available data suggest a significant benefit associated with CRT in patients with QRS ≥ 150 ms, but not in patients with QRS < 150 ms. Further studies are needed to identify patients with QRS < 150 ms who might benefit from CRT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 163‐168, February 2012)     

真性完全性左束支阻滞与心脏再同步化治疗超反应的研究进展

真性完全性左束支阻滞作为一个新概念被提出,不仅促进了心电学的发展,而且也丰富了心脏再同步化治疗心力衰竭的内容,并成为慢性心力衰竭伴真性完全性左束支阻滞的患者对心脏再同步化治疗获超反应的一个新的预测因子.     

Recurrent acute pulmonary oedema and cardiac arrest secondary to intermittent electrical dyssynchrony: a role for cardiac resynchronization despite preserved left ventricular function

Recurrent pulmonary oedema with no obvious precipitant can prove difficult to treat in patients with preserved left ventricular (LV) systolic function. This report describes the novel use of cardiac resynchronization therapy (CRT) in the prevention of acute pulmonary oedema precipitated by intermittent electrical dyssynchrony in a patient with preserved LV systolic function.     

Physiologic resynchronization therapy: a case of his bundle pacing reversing physiologic conduction in a patient with CHF and LBBB during 2 years of observation

This is a case of a patient with congestive heart failure and left bundle branch block who was referred for cardiac resynchronization therapy implantation. Instead, a His bundle pacing was achieved with a narrow QRS complex. During 27 months of observation, the patient improved dramatically from NYHA class IV to I. Echo parameters improved significantly the LV diameter from 75/50 to 60/40 mm, EF from 28 to 50%, and mitral regurgitation from 4 to 2°.     

左束支阻滞性心肌病

长期的真性左束支阻滞可引起左室扩大、心功能进行性下降,进而发展为伴有心功能不全的心肌病。这种左束支阻滞性心肌病的发病机制尚不明确,可能与左束支阻滞所致的电-机械活动失同步有关。该病的临床诊断过程与获得性心肌病一致,关键是识别真性左束支阻滞。心脏再同步化治疗能有效逆转左束支阻滞性心肌病。     

Cardiac resynchronization therapy and ventricular tachyarrhythmia burden

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右束支阻滞患者心脏再同步治疗疗效分析

目的 回顾分析阜外心血管病医院心律失常中心合并右束支阻滞(RBBB)的心力衰竭患者心脏再同步治疗(CRT)疗效.方法 本中心自2008年1月至2010年12月植入CRT-P/D的合并RBBB的心力衰竭患者,接受常规每3～6个月门诊随访,随访内容包括心功能(NYHA分级)、6 min步行距离、Minnesota生活质量评分、超声心动图及程控等指标.结果 共7例合并RBBB心力衰竭患者植入CRT-P/D,其中男6例,女1例,年龄19 ～74(57±19)岁.随访0.3～43.0(17.6±16.7)个月.随访期间发生心力衰竭住院事件7次,3例患者因心力衰竭加重死亡.6例患者为CRT无反应者,1例为CRT反应者.结论 合并RBBB的心力衰竭患者CRT无明显获益.     

The Effect of Weight Loss on Clinical Outcomes in Patients Implanted With a Cardiac Resynchronization Therapy Device—A MADIT-CRT Substudy

BackgroundThere are no data regarding the effect of weight loss on clinical outcomes in patients undergoing cardiac resynchronization therapy. This study was designed to evaluate the effect of weight loss on clinical outcomes in patients implanted with a cardiac resynchronization therapy with defibrillator (CRT-D).Methods and ResultsThe risk of heart failure (HF) or death, and of death alone, was compared between patients with and without weight loss of ≥2 kg or more at 1 year in the CRT-D arm of the Multicenter Automatic Defibrillator Implantation Trial–Cardiac Resynchronization Therapy (MADIT-CRT). Weight loss was observed in 170 of 994 patients (17%) implanted with a CRT-D. Multivariate analysis showed a significant increase in the risk of HF or death among patients with weight loss compared with those without weight loss (hazard ratio [HR] 1.82, 95% confidence interval [CI] 1.26–2.63; P = .001). Weight loss was associated with a 79% increase in the risk of all-cause mortality (HR 1.79, 95% CI 1.16–3.34; P = .01). When analyzed in a continuous fashion, each kg of weight loss was associated with a 4% increase in the risk of HF or death (P = .03). In left bundle branch block (LBBB) patients with a CRT-D, weight loss was associated with an especially high risk of HF or death (HR 2.23, 95% CI 1.36–3.65; P = .002) and of death alone (HR 2.33, 95% CI 1.07–5.06; P = .03; interaction P = .26).ConclusionsIn patients with mild symptoms of HF receiving CRT-D, weight loss observed at 1 year is associated with adverse clinical outcomes, especially in those with a LBBB electrocardiographic pattern.     

The value of the 12-lead ECG for evaluation and optimization of cardiac resynchronization therapy in daily clinical practice

Based on existing literature and some new data we propose a simple three-step strategy using the standard 12-lead ECG for patient selection and optimal delivery of cardiac resynchronization therapy (CRT). (1) Complete LBBB with regard to the indication for CRT can probably best be identified by a QRS duration of ≥ 130 ms for women and ≥ 120 ms for men with the presence of mid-QRS notch-/slurring in ≥ 2 contiguous leads of V₁, V₂, V₅, V₆, I and aVL. (2) Left ventricular (LV) free wall pacing should result in a positive QRS complex in lead V₁, with estimation of the exact LV lead position in the circumferential and apico-basal direction using lead aVF and the precordial leads, respectively. Wide and fractionated LV-paced QRS complexes may indicate pacing in scar tissue. (3) Atrioventricular and interventricular stimulation intervals may be optimized by adjusting them until precordial leads show fusion patterns between left and right ventricular activation wavefronts in the QRS complex.     

Cardiac resynchronization therapy by left bundle branch area pacing in patients with heart failure and left bundle branch block

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Cardiac Resynchronization Therapy Relieves Intractable Angina Due to Exercise‐Induced Left Bundle Branch Block Without Left Ventricular Systolic Dysfunction: A Detailed Case Study

Exercise‐induced left bundle branch block is rare and can be demonstrated with exercise testing. When the heart rate reaches a certain threshold, the QRS widens into left bundle branch block. This paper describes a patient with exercise‐induced left bundle branch block related angina and dyspnea, who responded to cardiac resynchronization therapy. We documented the potential benefits of cardiac resynchronization therapy with a left ventricular rapid pacing study prior to its implantation. Although exercise‐induced left bundle branch block is not a current indication for cardiac resynchronization therapy in patients such as ours, it could be considered when conventional drug therapy fails.     

Differentiation between left bundle branch block and left ventricular hypertrophy: Implications for cardiac resynchronization therapy

Recent clinical trials have demonstrated that cardiac resynchronization therapy (CRT) reduces heart failure hospitalizations and mortality in patients with complete left bundle branch block (LBBB), but potentially not those with right bundle branch block or nonspecific LV conduction delay, such as that due to LV hypertrophy (LVH). Furthermore, endocardial mapping and simulation studies have suggested that one-third of patients diagnosed with LBBB by conventional electrocardiographic criteria are misdiagnosed, and these patients likely have a combination of LVH, LV chamber dilatation and delayed initiation of LV activation (incomplete LBBB). Increase in LV size due to hypertrophy/dilatation and slowed intramyocardial conduction velocity prolong QRS duration in patients with LVH, which can frequently go above the QRS duration threshold of 120 ms conventionally used to diagnose LBBB. New strict criteria for diagnosing complete LBBB have been proposed that utilize longer QRS duration thresholds (130 ms in women and 140 ms in men) and require the presence of mid-QRS notching/slurring in at least 2 of the leads I, aVL, V1, V2, V5 or V6. The emergence of CRT has led to an increased need to differentiate complete LBBB from LVH and other types of intraventricular conduction delay, which should be further studied.