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Examples of intraventricular conduction delays on ECG. Counterclockwise from top left: LBBB, NIVCD, RBBB, right ventricular paced, bifascicular block (RBBB + LPFB), and bifascicular block (RBBB + LAFB)
Source publication
Purpose of review:
We sought to assess the utility of CRT in patients with non-LBBB.
Recent findings:
CRT has an established role as a device-based therapy for patients with HF with systolic dysfunction and intraventricular conduction disease, specifically LBBB. In modern practice, the use of CRT in non-LBBB patients remains controversial, with...
Similar publications
Cardiac resynchronisation therapy (CRT) using biventricular pacing is an established therapy for impairment of left ventricular (LV) systolic function in patients with heart failure (HF). Although technological advances have improved outcomes in patients undergoing biventricular pacing, the optimal placement of pacing leads remains challenging, and...
Aims
Investigate haemodynamic effects, and their mechanisms, of restoring atrioventricular (AV)-coupling using pacemaker therapy in normal and failing hearts in a combined computational–experimental–clinical study.
Methods and results
Computer simulations were performed in the CircAdapt model of the normal and failing human heart and circulation....
Background: Left bundle branch area pacing (LBBAP) has become a safe and effective option for heart failure (HF) patients indicated for cardiac resynchronization therapy (CRT) and/or ventricular pacing, yet the response rate was only 70%. Repolarization parameters were demonstrated to be associated with cardiac mechanics and systolic function. This...
Cardiac resynchronization therapy (CRT) is a well-established treatment modality for ambulatory patients with heart failure (HF) who have prolonged QRS, left bundle branch block, reduced left ventricular (LV) ejection fraction, and New York Heart Association class II-IV. CRT has been shown to induce reverse LV remodeling and improve HF symptoms and...
Citations
... In detailed studies on this, it has been suggested that this is due to the fact that radial dyssynchrony in patients with isolated Right Bundle Branch Block is not impaired in the case of moderate QRS width (<150 ms). 10 In addition, in a subgroup comparison analysis, it was noted that patients with left fascicular hemiblock in addition to RBBB had better CRT responses than HF patients with isolated RBBB. 11 Therefore, it is recommended to review different lead positions and pacing strategies in HF patients with RBBB. ...
Cardiac Resynchronization Therapy (CRT) is a treatment modality developed in the early 2000s that targets the mechanical and electrical dyssynchrony in heart failure with reduced ejection fraction (HFrEF) patients. Appropriate patient selection conditions specified in the guidelines include measurement of left ventricular systolic dysfunction, QRS width and assessment of functional classification. Despite consistent and increasing evidence supporting the use of CRT in eligible patients, proportion of patients with the device is still not at the desired level. In addition, studies conducted in recent years have shown that the CRT response of patients is quite heterogeneous and in
echocardiographic follow-up, it was observed that reverse remodeling was not at the supposed level in approximately one third of the patients. In order to change this result, which is due to many reasons, solutions such as using assistive imaging methods, providing optimal patient selection, trying different pacing techniques and post-procedural programming strategies (AV delay and VV delay optimization)
have been the subject of debate. In this article, we aim to review the mechanisms that have been revealed regarding the differences in CRT response and new pacing techniques - especially conduction system pacing- that may be preferred to resolve poor CRT response.
Keywords: cardiac resynchronization therapy, Cardiomyopathy, Congestive heart failure, Left ventricular dysfunction, Pacemaker
... Conversely, some patients without intrinsic LBBB may have HF improvement (12,13). These patients usually refers to right bundle-branch block (RBBB), intraventricular conduction delay (IVCD), and predominantly ventricular paced rhythm with non-physiologic depolarization pattern (14,15). Some post-hoc analyses of landmark RCTs have shown a wide range of CRT response for HFrEF patients without intrinsic LBBB (1,2,(16)(17)(18). ...
Background: Response rates for cardiac resynchronization therapy (CRT) in patients without intrinsic left bundle-branch block (LBBB) morphology are poor.
Objective: We sought to develop a nomogram model to predict response to CRT in patients without intrinsic LBBB.
Methods: We searched electronic health records for patients without intrinsic LBBB who underwent CRT at Mayo Clinic. Logistic regression and Cox proportional hazards regression analysis were performed for the odds of response to CRT and risk of death, respectively. Results were used to develop the nomogram model.
Results: 761 patients without intrinsic LBBB were identified. Six months after CRT, 47.8% of patients demonstrated improvement of left ventricular ejection fraction by more than 5%. The 1-, 3-, and 5-year survival rates were 95.9, 82.4, and 66.70%, respectively. Patients with CRT upgrade from pacemaker [odds ratio (OR), 1.67 (95% CI, 1.05–2.66)] or atrioventricular node (AVN) ablation [OR, 1.69 (95% CI, 1.09–2.64)] had a greater odds of CRT response than those patients who had new implant, or who did not undergo AVN ablation. Patients with right bundle-branch block had a low response rate (39.2%). Patients undergoing AVN ablation had a lower mortality rate than those without ablation [hazard ratio, 0.65 (95% CI, 0.46–0.91)]. Eight clinical variables were automatically selected to build a nomogram model and predict CRT response. The model had an area under the receiver operating characteristic curve of 0.71 (95% CI, 0.63–0.78).
Conclusions: Among patients without intrinsic LBBB undergoing CRT, upgrade from pacemaker and AVN ablation were favorable factors in achieving CRT response and better long-term outcomes.
... Importantly, close to one-third of patients receiving conventional biventricular pacing derive no detectable echocardiographic or clinical improvement from therapy, and this number may be higher in patients with non-LBBB patterns. (25) In contrast, HBP was associated with improvement in MR in patients who were chronically paced at baseline and patients with RBBB. ...
Background
Although His bundle pacing (HBP) has been shown to improve LV ejection fraction (LVEF), its impact on mitral regurgitation (MR) remains uncertain.
Objectives
The aim of this study was to evaluate change in functional MR after HBP in patients with left ventricular (LV) systolic dysfunction.
Methods
Paired echocardiograms were retrospectively assessed in patients with reduced LVEF (<50%) undergoing HBP for pacing or resynchronization. The primary outcomes assessed were change in MR, LVEF, LV volumes, and valve geometry pre and post-HBP. MR reduction was characterized as a decline in ≥1 MR grade post-HBP in patients with ≥ grade 3 MR at baseline.
Results
Thirty patients were analyzed: 68±15 yrs, 73% male, LVEF 32±10%, 38% CAD, 33% history of AF. Baseline QRS was 162±31 ms: 33% LBBB, 37% RBBB, 17% paced, and 13% narrow QRS. Significant reductions in LVESV (122 mL [73-152 mL] to 89 mL [71-122 mL], p=0.006) and increase in LVEF (31% [25-37%] to 39% [30-49%], p<0.001) were observed after HBP. Ten patients had Grade 3 or 4 MR at baseline, with reduction in MR was observed in 7. In patients with at least grade 3 MR at baseline, reduction in LV volumes, improved MV geometry, and greater LV contractility were associated with MR reduction. Greater reduction in paced QRS width was present in MR responders compared to non-MR responders (-40% vs -25%, p=0.04).
Conclusions
In this initial detailed echocardiographic analysis in patients with LV systolic dysfunction, HBP reduced functional MR through favorable ventricular remodeling.
... The role of CRT in patients with right bundle branch block (RBBB) or indeterminate interventricular conduction delay, socalled non-LBBB, is less clearly defined compared to LBBB. A recent review [97] stated the high rate of non-responders for CRT in RBBB, although some subpopulations might benefit from CRT, specifically by using mapping techniques. In ACHD patients heart failure is often related to right ventricular dysfunction whether it serves as the subpulmonic or the systemic ventricle (e.g. in ccTGA, or after atrial switch of TGA), and may also include RBBB or other interventricular conduction abnormalities. ...
Introduction
The population of adults with congenital heart disease (ACHD) is rapidly expanding and one of the major complications is heart failure. Timely diagnosis and treatment are crucial, but strong evidence for effectiveness of heart failure treatment in ACHD is currently lacking. Components of the medical history, physical examination and further diagnostic tests including ECG, echocardiography, cardiac magnetic resonance imaging, exercise testing, and biomarkers can identify patients at risk for early mortality or heart failure.
Areas covered
Although the number of studies guiding evidence-based treatment are expanding, many clinical questions have not been completely answered yet. Therefore, in this review we provide an overview of current available insights in epidemiology, diagnosis, risk stratification and treatment options in ACHD patients, including non-medical therapies and advanced care planning.
Expert Opinion
We strongly advocate expanding current use of biomarkers in the diagnostic process and timely initiation of discussing advanced treatment options and advanced care planning with patients and their loved ones. More research in multi-center collaborations is needed to study all aspects of care of adult congenital heart disease patients.
... Complete left bundle branch block was defined as QRS duration ≥120 milliseconds, QS or rS form in lead V1, and broad R waves without Q waves in lead I and V6. 7 Non-left bundle branch block included right bundle branch block, nonspecific intraventricular conduction delays, and predominantly paced rhythms with a nonphysiologic depolarization pattern. 8 Echocardiography Standard M-mode and 2-dimensional echocardiographic views were used to assess LV end-diastolic diameter and volume (LVEDD and LVEDV, respectively), end-systolic diameter and volume (LVESD and LVESV, respectively), and LVEF by modified Simpson's method. 9 Maximum transverse diameters at right ventricle (RV) basal, midlevel, and maximum longitudinal dimension were measured at end diastole. ...
Background
There are limited data about cardiac resynchronization therapy ( CRT ) in adult congenital heart disease. We aimed to assess early and late outcomes of CRT among patients with adult congenital heart disease.
Methods and Results
We retrospectively studied 54 patients with adult congenital heart disease (median age, 46 years; range, 18–73 years; 74% men) who received CRT implantation (biventricular paced >90%) between 2004 and 2017. Clinical and echocardiographic data were analyzed at baseline and early (mean±SD: 1.8±0.8 years) and late (4.7±0.8 years) follow‐up after CRT . Compared with baseline, CRT was associated with significant improvement at early follow‐up in New York Heart Association functional class, QRS duration, and cardiothoracic ratio ( P <0.05 for all); improvement in New York Heart Association class was sustained at late follow‐up. Among patients with a systemic left ventricle ( LV ; n=39), there was significant increase in LV ejection fraction and reduction in LV end‐systolic volume at early and late follow‐up ( P <0.05 for both). For patients with a systemic right ventricle (n=15), there was a significant early but not late reduction in systemic right ventricular basal and longitudinal diameters. Eleven patients died, and 2 had heart transplantation unrelated to systemic ventricular morphological characteristics. Thirty‐five patients (65%) responded positively to CRT , but only baseline QRS duration was predictive of a positive response.
Conclusions
CRT results in sustained improvement in functional class, systemic LV size, and function. Patients with a systemic LV and prolonged QRS duration, independent of QRS morphological characteristics, were most likely to respond to CRT .
... that respond to resynchronization, such as those with prolonged PR intervals (≥230 ms; Lin, Buhr, & Kipp, 2017), with RBBB and concomitant left-sided delay and those with significant burden of right ventricular pacing (Belkin & Upadhyay, 2017). Females show true LBBB pattern at shorter QRSd and have more frequent mechanical dyssynchrony at shorter QRSd related to males. ...
The criteria for left bundle branch block have gained growing interest in the last few years. In this overview, we discuss diagnostic and prognostic aspects of different criteria. It was already shown that stricter criteria, including longer QRS duration and slurring/notching of the QRS, better identify responders to cardiac resynchronization therapy. We also include aspects of ST/T concordance and discordance and vectorcardiography, which could further improve in the fine‐tuning of the left bundle branch criteria.
... As the Irx genes are critical for efficient conduction in the VCS development, defects of Irx genes may be associated with arrhythmia. Loss of Irx3 leads to demolition of the rapid concerted spread of excitation in ventricles, prolonged QRS, notched R waves (R') and an increase of HV interval, right bundle branch block to be specific, which is considered to be associated with increase of mortality in patients with acute myocardial infarction [108], and a reasonable candidate of cardiac resynchronization therapy for heart failure patients with evidence of either electrical or mechanical left-sided delay [109]. ...
Iroquois homeobox genes, Irx, encode cardiac transcription factors, Irx1-6 in most mammals. These six transcription factors are expressed in different patterns mainly in the ventricular part of the heart. Existing researches show that Irx genes play key roles in the differentiation and development of ventricular conduction system and the establishment and maintenance of gradient expression of potassium channels, Kv4.2. Our main focus of this review is on the recent advances in the discovery of above-mentioned genes and the function of the encoding products, how Irx genes establish ventricular conduction system and regulate ventricular repolarization, how the individual and complementary functions can be verified to complement our cognition and leads to novel therapeutic approaches.
In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His‐bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra‐Hisian left bundle branch (LBB) or distal His‐bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high‐grade atrioventricular (AV) block and RBBB pattern.
Objectives
This study compared clinical outcomes between an increased electrical delay in the left ventricular region (QLV)-based LV lead implantation approach (QLV arm) and anatomical implantation approach (control arm) in patients with non-left bundle branch block.
Background
Limited data exist on cardiac resynchronization therapy effectiveness in patients with non-left bundle branch block. Clinicians generally deliver cardiac resynchronization therapy through an anatomical implantation approach; however, targeting the QLV may serve as an individualized implantation strategy in non-left bundle branch block patients.
Methods
The study enrolled 248 subjects at 29 U.S. centers. Subjects were randomized in a 2:1 ratio between a QLV-based implantation approach and anatomical implantation approach and were implanted with a St. Jude Medical quadripolar cardiac resynchronization therapy defibrillator system. The primary endpoint was the clinical composite score after 12 months of follow-up.
Results
The study analyzed 191 available subjects at 12 months of follow-up (128 QLV arm, 63 control arm). Of these, 39 subjects (26 in the QLV arm and 13 in the control arm) had heart failure events (8 cardiac deaths and 31 heart failure hospitalizations). Aside from New York Heart Association functional class, there were no other significant differences in baseline characteristics between the 2 arms. The responder rate at 12 months measured by the clinical composite score was 67.2% in the QLV arm and 73.0% in the control arm (p = 0.506).
Conclusions
Although patient-tailored left ventricular lead placement guided by QLV is promising, we observed no difference in outcome between the QLV-based implantation approach and the conventional anatomical implantation approach.
