РЕМОДЕЛИРОВАНИЕ СЕРДЦА И ПРОГНОЗ БОЛЬНЫХ С ХРОНИЧЕСКОЙ СЕРДЕЧНОЙ НЕДОСТАТОЧНОСТЬЮ ПРИ НАЛИЧИИ ПОЛНОЙ БЛОКАДЫ ЛЕВОЙ НОЖКИ ПУЧКА ГИСА

Complete bundle branch block as an independent predictor of all-cause mortality: report of 7,073 patients referred for nuclear exercise testing

Objective To investigate left ventricular (LV) radial dyssynchrony and LV rotational change of isolated complete left bundle branch block (CLBBB) and CLBBB with heart failure (HF).Methods Twenty-six isolated CLBBB patients,twenty-four CLBBB patients with HF and twenty healthy controls were studied.Two-dimensional speckle tracking imaging (2D-STI) was applied to short-axis views to calculate LV radial dyssynchrony and LV rotational and twist degree and time to peak rotational and twist degree.Results LV radial dyssynchrony and LV rotation and twist degree were intermediately damaged in isolated CLBBB patients and was significantly damaged in CLBBB patients with HF,compared with healthy controls.Conclusions For isolated CLBBB patients,even if LV ejection fraction was in the normal range,another parameters of cardiac mechanic had changed and 2DSTI could be used to evaluate these alterations. Key words: Echocardiography; Bundle-branch block; Ventricular function,left; Speckle tracking imaging

<i>Circulation: Arrhythmia and Electrophysiology</i> Editors’ Picks

Dyssynchrony and the Risk of Ventricular Arrhythmias

ST-Segment Elevation in Electrocardiogram Lead aVR

Purpose: Chronic heart failure (HF) patients with a left ventricular (LV) conduction delay, mostly due to left bundle branch block (LBBB), derive benefit from cardiac resynchronization therapy (CRT). However, approximately 30% of patients do not improve clinically after CRT. We investigated whether T-wave analysis can improve patient selection. Methods: The study population comprised 335 CRT recipients with baseline 12-lead electrocardiogram recordings. Echocardiographic response after 6-months CRT was defined as a ≥ 5% increase in LV ejection fraction (LVEF). Patients were assessed for HF hospitalization and death separately, as well as both combined with heart transplantation and LVAD implantation (HTLD) at 3 years follow-up. T-wave area was determined in vectorcardiograms (VCGs), constructed from digital 12-lead ECGs using an adapted Kors method. Results: Logistic regression models indicated repolarization variables as good predictors of CRT response. The VCG-derived T-wave area predicted CRT response (odds ratio (OR) per 10 μVs increase 1.172 (p &lt; 0.001)), even better than QRS-wave area (OR = 1.116 (p = 0.001)). T-wave area had especially predictive value in LBBB patients (OR = 2.77 in LBBB vs. 1.09 in non-LBBB). This predictive value persisted after adjustment for multiple covariates, such as gender, ischemia, age, hypertension, coronary artery bypass graft, and the usage of diuretics and beta-blockers. The table depicts that patients with large T-wave area showed a larger increase in LVEF and a lower occurrence of the end-points HF hospitalization, death and HTLD, as compared to those with a small T-wave area, the difference being significant for LBBB patients. Conclusions: In patients with LBBB morphology of the QRS complex, a larger baseline T-wave area is an important additional predictor of both volumetric and long-term clinical response following CRT.

Electrocardiographic (ECG) features of left bundle branch (LBB) block (LBBB) can be observed in up to 20%-30% of patients suffering from heart failure with reduced ejection fraction. However, predicting which LBBB patients will benefit from cardiac resynchronization therapy (CRT) or conduction system pacing remains challenging. This study aimed to establish a translational model of LBBB to enhance our understanding of its pathophysiology and improve therapeutic approaches. Fourteen male pigs underwent radiofrequency catheter ablation of the proximal LBB under fluoroscopy and ECG guidance. Comprehensive clinical assessments (12-lead ECG, bloodsampling, echocardiography, electroanatomical mapping) were conducted before LBBB induction, after 7, and 21days. Three pigs received CRT pacemakers 7days after LBB ablation to assess resynchronization feasibility. Following proximal LBB ablation, ECGs displayed characteristic LBBB features, including QRS widening, slurring in left lateral leads, and QRS axis changes. QRS duration increased from 64.2 ± 4.2ms to 86.6 ± 12.1ms, and R wave peak time in V6 extended from 21.3 ± 3.6ms to 45.7 ± 12.6ms. Echocardiography confirmed cardiac electromechanical dyssynchrony, with septal flash appearance, prolonged septal-to-posterior-wall motion delay, and extended ventricular electromechanical delays. Electroanatomical mapping revealed a left ventricular breakthrough site shift and significantly prolonged left ventricular activation times. RF-induced LBBB persisted for 3weeks. CRT reduced QRS duration to 75.9 ± 8.6ms, demonstrating successful resynchronization. This porcine model accurately replicates the electrical and electromechanical characteristics of LBBB observed in patients. It provides a practical, cost-effective, and reproducible platform to investigate molecular and translational aspects of cardiac electromechanical dyssynchrony in a controlled and clinically relevant setting.

Objective:Left ventricular (LV) rotation and twist play an important role in LV contraction and relaxation. Left bundle branch block (LBBB) deteriorates both diastolic and systolic functions. We evaluated the LV twist in patients with LBBB and preserved ejection fraction (EF) (>50%) to determine twist as a potential marker for subtle myocardial dysfunction.Methods:This observational cross-sectional study included 34 LBBB patients with preserved EF who were free from ischemic and valvular disease (Group 1) and 36 healthy controls (Group 2). All patients underwent 2-D Doppler and 2-D speckle tracking echocardiography. LV apical, basal rotation, and twist were evaluated in both groups and compared accordingly. In addition, subjects were dichotomized considering the median twist value of the study population. Binary logistic regression analysis was performed to determine the independent variables associated with inframedian twist.Results:Baseline clinical characteristics were similar in LBBB patients and controls. Mean apical rotation (2.5°±1.9° vs. 4.4°±2.9°; p=0.002), basal rotation (-2.9°±2.3° vs. -4.1°±2.7°; p=0.05), and twist (5.4°±3° vs. 8.6°±3.3°; p<0.001) were decreased in group 1. Parameters related to intra- and interventricular mechanical dyssynchrony, such as longitudinal left ventricular dyssynchrony index (LVdys) and preejection interval of LV, interventricular mechanical delay (IVMD), and left posterior wall contractions (SPMWD) were significantly higher in the LBBB group. The median twist value of the studied population was 6.65°. Binary logistic regression analysis showed that only presence of LBBB was independently associated with inframedian twist (OR=6.250; 95% CI: 2.215–17.632; p<0.001).ConclusionThe LBBB might have induced the reduction of LV twist by diminishing the LV rotation before inducing a prominent effect on the left ventricular ejection fraction (LVEF). Therefore, twist may be considered as a marker for subtle LV dysfunction in LBBB with substantially normal EF.

Background The impact of left bundle branch block (LBBB) on left ventricular (LV) myocardial work may vary according to the specific definition of a LBBB. Quantification of the interplay between LV myocardial work and the underlying electrical dyssynchrony may improve our understanding of cardiac resynchronization therapy (CRT) response. Objective To evaluate the impact of LBBB, defined according to Strauss and ESC 2013 ECG criteria, as well as non-LBBB morphologies on different LV myocardial work indices and response to CRT. Methods LBBB was defined according to the Strauss criteria and ESC 2013 guidelines on heart failure. LV myocardial constructive and wasted work (CW and WW) were derived from pressure-strain loop analysis integrating valvular opening and closing times, speckle tracking strain echocardiography and noninvasive blood pressure measurement. LV myocardial work efficiency (WE) was calculated from the ratio of constructive work, divided by the sum of constructive and wasted work. CRT response was defined as a decrease in LV end-diastolic volume (EDV) ≥15% at 6 months' follow-up. Results Patients were divided into 3 groups: 1) LBBB according to Strauss criteria (group 1, n=109, age 64±10 years), 2) LBBB according to ESC 2013 criteria (group 2, n=22, age 64±10 years) and 3) non-LBBB (group 3, n=44, age 69±10 years). Patients from group 1 were 4.2 times more likely to respond to CRT than patients from group 3 (odds ratio [OR] 4.182; 95% confidence interval [CI], 1.999–8.750; p&lt;0.001), whereas CRT response between groups 2 and 3 did not differ significantly (OR 1.100; 95% CI 0.387–3.124; p=0.859). Patients in group 1, were characterized by significantly lower WE, compared to groups 2 and 3 (67.6±9.9 mmHg% vs. 72.7±9.7 mmHg% and 75.4±9.6 mmHg%, respectively; p&lt;0.001) as well as higher WW (313.2±144.9 mmHg% vs. 215.1±102.5 mmHg% and 229.0±113.5 mmHg%, respectively; p&lt;0.001). There was no significant difference in CW between any of the groups (811.6±353.4 mmHg% vs. 798.6±440.6 mmHg% and 893.6±420.2 mmHg% respectively for groups 1, 2 and 3; p=0.447). Conclusion Patients with a LBBB according to Strauss criteria had a higher probability of response to CRT, compared to those with a LBBB defined by ESC 2013 guidelines criteria or with non-LBBB morphology. This is reflected in a greater amount of wasted work and more impaired LV myocardial work efficiency at baseline in patients with LBBB satisfying Strauss criteria, compared to the other two groups, representing the substrate for CRT. Acknowledgement/Funding Study was supported by ESC Research grant 2018

Objective To explore the effect of different strain patterns on left ventricular systolic function and synchrony in complete left bundle branch block (CLBBB) patients using two-dimensional speckle tracking imaging (2D-STI). Methods Ninety patients with CLBBB were included from April 2016 to April 2018. The patients with CLBBB were divided into two groups based on the criteria of classic pattern of dyssynchrony (CPD) and non-classic pattern of dyssynchrony (n-CPD). Furthermore, patients with left ventricular ejection fraction (LVEF)> 50% were further selected and divided into a CPD group and n-CPD group as above. Thirty healthy subjects were included as controls. Common echocardiography and 2D-STI were performed. Left ventricular end-diastolic dimension and volume (LVEDD and LVEDV) as well as left ventricular ejection fraction (LVEF) were measured. Global left ventricular longitudinal strain (GLS), interventricular mechanical delay time (IVMD), basal-segment strain septal to lateral strain peak time delay (b-Ssl), mid-segment septal to lateral strain peak time delay (m-Ssl), and standard deviation of time to longitudinal strain peak for the left ventricular 18 segments (SDt) were measured and calculated. Results LAD, RVBD, E/e′, LVEDD, and LVEDV values in the CPD and n-CPD groups were significantly higher than those in the control group, and E/A and EDT in the CPD and n-CPD groups were significantly lower than those in the control group (t=5.12, 3.67, 7.29, 5.69, 5.89, 3.15, 2.05, 5.89, 5.22, and 3.83, P 50% were selected for comparisons, and there was no significant difference in LVEF between the two groups (P>0.05). Compared with the healthy control group, QRS, LVEDD, LVESD, LVEDV, LVESV, IVMD, b-Ssl, m-Ssl, and SDt values were significantly higher and Sept-LS, Lat-LS, and GLS values were significantly lower (t=19.44, 4.01, 5.21, 5.61, 4.73, 9.19, 5.27, 3.16, 3.25, 8.02, 4.15, and 5.42, respectively, P<0.001) in the CPD group; QRS, LVEDD, LVEDV, LVESV, IVMD, b-Ssl, m-Ssl, and SDt values were significantly higher and Sept-LS and GLS values were significantly lower (t=20.68, 2.46, 3.15, 3.10, 6.95, 3.00, 4.59, 6.53, 3.84, and 4.05, respectively, P<0.05) in the n-CPD group. Compared with the n-CPD group, QRS, LVEDD, LVESD, LVEDV, LVESV, IVMD, b-Ssl, and SDt values in CPD group were significantly higher and Sept-LS, Lat- LS, and GLS values were significantly lower (t=2.73, 2.13, 3.88, 3.06, 2.19, 3.94, 3.00, 3.25, 4.38, 2.90, and 2.30, respectively, P<0.05l) in the CPD group. Conclusion Conventional echocardiography combined with 2D-STI technology can early detect reduced systolic function and systolic synchronicity of the left ventricle in CLBBB patients, as well as the phenomenon that the systolic function and systolic synchronicity are further decreased in typical CLBBB compared with non-typical CLBBB, which can prompt clinical attention to typical CLBBB patients and timely treatment intervention. Key words: Echocardiography; Complete left bundle branch block; Systolic function; Systolic synchrony

Clinical-electrocardiographic correlates of newly acquired left bundle branch block: The Framingham study

Several studies have already established the superiority of cardiac resynchronisation therapy (CRT)-defibrillator (D) over implantable cardioverter-defibrillator (ICD) alone in patients with severely symptomatic chronic heart failure (New York Heart Association (NYHA) class III/IV), left ventricular (LV) systolic dysfunction, and a wide QRS complex. Synchronous pacing of opposing LV walls in malfunctioning asynchronously contracting LV regions creates resynchronisation with restoration of LV motion dynamics. In the Multicenter Automatic Defibrillator Implantation Trial-CRT (MADIT-CRT) study, a reduction in mortality or hospitalisation for congestive heart failure with CRT-D was observed compared with ICD. However, no difference in mortality was noted between the two groups. The COMPANION study established the superiority of CRT-D over optimal medical management alone in reducing all-cause mortality patients with NYHA class III/IV symptoms. While improvements in LV dimensions with CRT in patients with mildly asymptomatic heart failure were observed in the MIRACLE ICD-II and REVERSE trials, there were no significant differences in clinical endpoints in these studies. The MADIT-CRT study showed a significant reduction in the composite endpoint of mortality or heart failure events in similar patients with NYHA class I/II symptoms over a mean follow-up of 2 years. However, no significant difference in all-cause mortality between the two groups was noted. At the November 2010 meeting of the AHA in Chicago, the results of the Resynchronization–Defibrillation for Ambulatory Heart Failure Trial (RAFT) study were presented by Dr. Anthony Tang, Ottawa, Canada and recently published in the New England Journal of Medicine [1]. In the RAFT study, the safety and efficacy of CRT-D compared with ICD alone were investigated in patients with NYHA class II/III, LV systolic dysfunction (left ventricular ejection fraction (LVEF), ≤30%), and a wide QRS complex. All patients had been scheduled for ICD implantation for primary or secondary prevention of sudden cardiac death. The primary endpoint of the study was all-cause mortality or hospitalisation for worsening congestive heart failure. A total of 1798 patients (mean age, 66 years; 17% women) were randomised to either CRT-D (n = 894) or to ICD alone (n = 904). Two thirds of the patients had ischaemic cardiomyopathy. The majority of patients (80%) had NYHA class II and a mean LVEF of 22%. Permanent atrial fibrillation or flutter was seen in 13% of the patients. Patients were optimally treated, and the mean duration of follow-up was 40 months. Medtronic transvenous devices and leads were used in both groups. The LV lead was positioned in the lateral or posterolateral walls. Programming was set to minimise right ventricular pacing in the ICD arm and to maximise biventricular pacing in the CRT-D arm. The mean nonpaced QRS complex was 158 ms, and the mean paced QRS complex was 208 ms. A left bundle branch block (LBBB) pattern was noted in 72% of the patients. An LV lead was successfully placed in 95% of the patients in the CRT-D arm, and there was a 10% crossover to the CRT-D arm from the ICD arm. The main results of the RAFT study showed that the primary endpoint of all-cause mortality or hospitalisation for heart failure was significantly reduced in the CRT-D arm compared with ICD (40.3% versus 33.2%, p < 0.001). All-cause mortality was also significantly decreased (26.1% versus 20.8%, p = 0.003). This corresponded to a number needed to treat of 14 patients for 5 years to prevent one death with CRT-D compared with ICD alone. Hospitalisation for congestive heart failure was similarly reduced (26.1% versus 19.5%, p < 0.001). Results for the primary and secondary endpoints were similar for NYHA class II or III patients. Subgroup analysis showed a greater benefit with CRT-D in patients with wider QRS complex at baseline (≥150 ms for native and ≥200 ms for paced). LBBB morphology also seemed to derive greater benefit, and there was a trend towards greater efficacy in women. However, device-related hospitalisations were higher in the CRT-D arm (20.0% versus 12.2%, p < 0.001). Device- or implantation-related complications were significantly higher in the CRT-D arm, as compared with the ICD arm at 30 days (13.3% versus 6.8%, p < 0.001). The complications included haemothorax or pneumothorax, device-pocket haematomas, device-pocket infections, and lead displacement requiring intervention. The results of the RAFT study clearly indicate that in patients with NYHA class II/III (80% class II!), LV systolic dysfunction (LVEF, <30%), and a wide QRS complex, the addition of CRT to an ICD reduces all-cause mortality and hospitalisation for congestive heart failure by about 25%. On subgroup analysis, the results of the primary endpoint seemed to be more outspoken in patients with a wider QRS complex at baseline and those with LBBB morphology. There was a significant increase (twofold!) in the risk of device- or procedure-related complications at 30 days in the CRT-D arm, including a higher risk of hospitalisation for device-related causes. The higher complication rates in the RAFT trial are similar to those noted by other CRT-D trials, and careful attention to complications is therefore essential. Further studies are needed to identify optimal LV lead placement for maximal benefit and the cost-effectiveness of extending CRT-D to mildly symptomatic patients. In an accompanying editorial, Dr. Arthur Moss (Rochester, NY, USA) stated, ‘we can say that recent findings documenting the use of CRT in preventing heart failure in minimally symptomatic patients are breathtaking’ [2].

Background/Objectives: COVID-19 is associated with multiple systemic effects, including cardiovascular complications. However, its interplay with cardiac conduction abnormalities remains underexplored. We compared the clinical profile of COVID-19 patients with pre-existing left bundle branch block (LBBB) or right bundle branch block (RBBB) at hospital admission. Methods: This study included 100 COVID-19 patients with antecedent BBB (50 LBBB, 50 RBBB). Critical cardiometabolic, renal, hematological, and inflammatory markers were measured. Logistic regression was used to identify key predictors differentiating COVID-19 patients with LBBB and RBBB. Spearman's correlations were applied to assess intra-strata associations for these variables. Results: COVID-19 patients with LBBB patients were significantly more likely to display lower systolic blood pressure (p = 0.012) but greater left atrial size (p = 0.008), left ventricular diameter (p = 0.001), and interventricular septal thickness (p = 0.023). Hematological and inflammatory markers differed, with LBBB patients being prone to exhibit higher red cell distribution width (p = 0.005), lymphocyte count (p < 0.001), neutrophil count (p = 0.045), and C-reactive protein (p < 0.001). This group also tended to show lower erythrocyte sedimentation rate (p = 0.013) and glycated hemoglobin (p = 0.045) but higher random glucose (p = 0.014). Absolute lymphocyte count, C-reactive protein, and left ventricular diameter were the most robust predictors distinguishing LBBB from RBBB. Significant associations were found exclusively for LBBB, all of them being weak. These predominantly negative relationships indicated an inflammatory origin, and most of them occurred for lymphocyte count. Conclusions: COVID-19 patients with LBBB and RBBB present distinct clinical profiles at hospital admission. The former group demonstrates a more adverse baseline clinical profile, particularly in terms of cardiac and inflammatory markers. These findings suggest that pre-existing BBB type may influence disease progression, potentially helping in risk stratification for COVID-19 patients.

Background and ObjectivesThe impact of left bundle branch block (LBBB) on left atrial (LA) dyssynchrony in heart failure (HF) patients with non-ischemic dilated cardiomyopathy (DCM) has not been clearly elucidated.MethodsEighty consecutive symptomatic HF patients with non-ischemic DCM (left ventricular ejection fraction, LVEF<35%) were included. LBBB was defined on electrocardiography. Left ventricular (LV) systolic and diastolic dyssynchrony index and LA dyssynchrony index were obtained by color-coded tissue Doppler imaging.ResultsThere was no significant difference in LV size, LVEF, LV global longitudinal strain, peak atrial longitudinal strain and LA volume between patients with LBBB (n=38) and no LBBB (n=42). There was a significant difference in LV systolic dyssynchrony index (p=0.014) and there was a mild difference in LV diastolic synchronicity index (p=0.045) between patients with LBBB and no LBBB. However, there was no difference in LA dyssynchrony index between the 2 groups (p=0.60). LA dyssynchrony index was not related to LV systolic and diastolic dyssynchrony indexes, but it was related to the deceleration time of mitral early diastolic velocity (E), the ratio of E to mitral annular early diastolic velocity (E/e′) and LA volume. E/e′ was most related to LA dyssynchrony index (r2=0.325, p=0.002).ConclusionsLBBB influences both LV systolic and diastolic dyssynchrony, but not LA dyssynchrony. LA dyssynchrony was related to LV diastolic function regardless of the presence of LBBB in in patients with non-ischemic DCM.

Significance of complete left bundle branch block with left axis deviation.