Modeling an Activation of Heart Ventricular Segments

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.

Autocorrelation maps for optimal setting in cardiac resynchronization therapy

Electromechanical delay by speckle-tracking echocardiography: A novel tool to distinguish between Brugada syndrome and isolated right bundle branch block

Dyssynchrony and the Risk of Ventricular Arrhythmias

The study investigates the prognostic impact of right bundle branch block (RBBB) and left bundle branch block (LBBB) in patients with cardiogenic shock (CS) compared with no bundle branch block (BBB). In patients with heart failure, existence of RBBB and LBBB has influence on prognosis. Prospective registry-study. ICU of a tertiary academic hospital in Germany. Adult patients with CS. None. Consecutive patients with CS were included. The prognostic impact of RBBB and LBBB on 30-day all-cause mortality was tested within the entire cohort and in the subgroup of CS patients with cardiac arrest at admission. The final study cohort comprised 248 patients. Patients with RBBB showed the highest 30-day all-cause mortality followed by LBBB and no BBB (72.5% vs. 52.9% vs. 50.0%; log-rank p = 0.015). These findings were consistent even after solely including CS patients with cardiac arrest (90.0% vs. 73.3% vs. 62.2%; log-rank p = 0.008). After adjustment for lactate, norepinephrine, troponin I, Acute Physiology Score, Society of Cardiovascular Angiography & Interventions shock stage, and heart rate in a multivariable Cox regression analysis, RBBB still revealed a negative impact on 30-day all-cause mortality (hazard ratio [HR], 1.807; 95% CI, 1.107-2.947; p = 0.018), whereas LBBB was not associated with 30-day all-cause mortality. In this multivariable Cox regression model lactate (HR, 1.065; 95% CI, 1.018-1.115; p = 0.006), troponin I (HR, 1.003; 95% CI, 1.001-1.005; p = 0.001), and Acute Physiology Score (HR, 1.033; 95% CI, 1.001-1.066; p = 0.041) were as well associated with 30-day all-cause mortality. Finally, no association of RBBB was found with the incidence of liver or severe renal failure. Besides the Acute Physiology Score, lactate, and troponin levels, RBBB was associated with an increased 30-day all-cause mortality in consecutive CS patients with and without cardiac arrest, whereas LBBB showed no prognostic impact.

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.

Aim: To investigate echocardiography (EchoCG) parameters and clinical prognosis in elderly patients with chronic heart failure (CHF) and complete left bundle branch block (LBBB). Material and methods: The study included 248 patients (163 men and 85 women), aged 60–85 years, with Functional Class II–IV CHF (NYHA classification) due to coronary heart disease (CHD) and arterial hypertension (AH). All participants were divided into two groups: Group I (n=37) included patients with complete LBBB, while Group II (n=211) included patients without LBBB. Results: In 14,9% of the elderly CHF patients, complete LBBB was observed. Group I and II patients were comparable by age, gender, CHF duration, and hemodynamic parameters. However, clinical course of CHF was more severe in participants with complete LBBB. LBBB was associated with myocardial infarction (MI) in anamnesis (p=0,029; odds ratio, OR, 5,11; 95% confidence interval, CI, 1,19–22,03), anterior MI (р=0,020; OR 3,03; 95% CI 1,19–1,71), left ventricular (LV) end-diastolic dimension (р=0,001; OR 2,09; 95% CI 1,35–3,26), LV end-systolic dimension (р=0,001; OR 1,98; 95% CI 1,34–2,95), LV end-diastolic volume (р=0,001; OR 1,012; 95% CI 1,01–1,02), LV end-systolic volume (р=0,002; OR 1,01; 95% CI 1,01–1,02), and low LV ejection fraction (EF) (р=0,003; OR 1,05; 95% CI 1,02–1,08). Over the follow-up period, the survival levels in elderly CHF patients with or without LBBB were 59,5% and 76,8%, respectively. The leading mortality cause in patients with LBBB was sudden death. Conclusion: Complete LBBB was associated with LV remodelling progression. Sudden death was the leading mortality cause in LBBB patients.

Funding Acknowledgements Type of funding sources: None. Introduction Various studies have questioned the magnitude of the benefit of cardiac resynchronization therapy (CRT) in patients without left bundle branch block (LBBB). This worse response could be due to the suboptimal location of the electrodes. Purpose We hypothesize that in non-LBBB patients, an implant guided by ventricular electroanatomic mapping by locating the areas with the greatest activation delay will improve the outcome of CRT. Material and methods We included 7 patients non-LBBB. To locate the most delayed activation zones, an electromagnetic activation map was created using the Ensite Precision navigator connected to the right ventricular catheter and to a guidewire with electrical recording capacity at its distal end. ECG, clinical, and echocardiographic data were recorded at baseline and post-implantation, compared with 7 patients LBBB (control group). Results In non-LBBB patients, several activation patterns could be defined according to the conduction disorder, including right bundle branch block (RBBB)+left anterior hemiblock (figure 1A) or RBBB alone (figure 1B). All patients with non-LBBB improved at follow-up in the NYHA functional class (p=0,011) and in the Minnesota test (7,85±4,63; p=0.004). The mean reduction in QRS duration was 14,57±9,86 ms (p=0.008), LVEF increased 8.22±4.62 ms (p=0.003), LVOTS decreased by 15,71±12,23 ml (p=0.015) and the LVEDV in 10,42±5,15 ml (p=0.002). There were no significant differences between the response to CTR in non-LBBB patients and LBBB patients (table 1), including LVEF (8.22±4.62 vs 11.54±5.54, p=0.248) and difference in Minnesota test (7.85±4.63 vs 9.71±5.87, p=0.524). Conclusions CRT guided by electroanatomical mapping produced significant clinical and structural improvement in non-LBBB patients. This improvement was of a similar magnitude to LBBB patients. Various patterns of ventricular activation according to the conduction disorder were observed.

Comparison of Left Ventricular Torsion and Strain With Biventricular Pacing in Patients With Underlying Right Bundle Branch Block Versus Those With Left Bundle Branch Block

BackgroundPacemaker implantation involves intraoperative testing of ventricular sensing using a device called a pacing system analyzer (PSA). The value obtained is expected to correspond to those taken by the pacemaker after its implantation. This study determined the latency period for sensing intracardiac electrogram (EGM) by the right ventricular (RV) lead.MethodsPatients without significant heart disease and underlying intrinsic atrioventricular (AV) conduction underwent Medtronic or Abbott dual‐chamber pacemaker implantation with the RV lead positioned on the mid‐septum. Real‐time sensing data were obtained through PSA and after pacemaker implantation to evaluate latency as the time interval Q‐VS between the onset of QRS on surface electrocardiogram and the sensed EGM by the RV lead.ResultsOf 157 patients, 105 had narrow QRS (<120 ms) and 52 had wide QRS of complete right bundle branch block (RBBB). Both narrow‐QRS and RBBB patients had longer sensing latency through PSA (50.9 ± 24.2 and 67.8 ± 32.9 ms, respectively) than through pacemaker (18.2 ± 12.8 and 31.2 ± 14.8 ms, respectively, both p < 0.001). RBBB patients had longer sensing latency compared with narrow QRS patients, either through PSA or through pacemaker (p < 0.001). The sensing latency of Medtronic recipients was longer than those of Abbott in narrow‐QRS (p < 0.05), but not in RBBB.ConclusionWe demonstrated longer RV lead sensing latency (1) through PSA than through pacemaker, (2) in RBBB than in narrow‐QRS, and (3) in Medtronic pacemakers compared with Abbott pacemakers. Knowledge of sensing latency helps the optimization of the AV delay.

Prevalence and Prognostic Implications of Bundle Branch Block in Comatose Survivors of Out-of-Hospital Cardiac Arrest

Electrocardiographic Findings in Patients With Acute Coronary Syndrome Presenting With Out-of-Hospital Cardiac Arrest

QRS width is a well known prognostic factor in ICD patients, however there is less information regarding bundle branch block morphology. Umbrella is a Spanish multicenter, prospective, observational registry sponsored by Medtronic including ICD patients from 39 centers followed by CareLink System. To analyze the influence of QRS width and morphology of bundle branch block in ventricular tachycardia (VT) or fibrillation (VF) recurrences, we studied patients from 27 participating centers followed between 1/04/2007 and 01/07/2012. Results: We included 568 patients (age 63.8±14, EF 33.1±9.4, QRS width 109±27ms), 77 (13.6%) of them with left bundle branch block (LBBB), and 49 (8.6%) with right bundle branch block (RBBB), and followed them during 23.3±18 months. LBBB was associated with more episodes of VT/VF, more shocks related to VT/VF and the occurrence of more than 3 episodes of VT/VF during follow-up (Table 1). Neither ejection fraction nor RBBB had any significant association to shocks or arrhythmia incidence. Width of QRS complex was only associated with a higher number of shocks (109±29 vs 120±25, p=0.002) and more than 3 episodes of VT/VF (109±29 vs 120±27, p=0.003) during follow-up. View this table: Table 1 Conclusion: Patients with LBBB had significantly more arrhythmic events compared to patients without LBBB. In our study EF and RBBB do not have prognostic relevance. QRS width has limited value. Further studies are needed to contrast these findings.

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.

The prognostic value of stress echocardiography (SE) in patients with complete bundle branch blocks (BBB) with normal left ventricular ejection fraction (LVEF) has not been well described. We sought to determine the prognostic value of SE in patients with BBB and normal LVEF. We analyzed 7214 patients (58 ± 14 years; 57% female) with a mean follow-up time of 9 ± 4 years. Dobutamine SE was performed in 51% of patients and exercise SE was performed in 49%. All-cause mortality data were obtained from the Social Security Death Index. There were 222 (3%) patients with right bundle branch block (RBBB) and 50 (0.7%) patients with left bundle branch block (LBBB). Patients with LBBB were 3 times more likely to have an abnormal stress test after adjusting for age, gender, mode of stress test, and coronary artery disease risk factors (OR = 3.3; 95% CI: 1.86-5.92; P < 0.001). The mortality rates were 4.5%/year for patients with LBBB, 2.5%/year for patients with RBBB, and 1.9%/year for patients without BBB (P < 0.001). Among patients with a normal SE, those with LBBB had similar mortality to those without LBBB (HR = 0.9; 95% CI: 0.4-2.2; P = 0.8). Patients with LBBB and abnormal SE had more than 2 times greater risk of all-cause mortality (HR = 2.4; 95% CI: 1.4-4.2; P = 0.002). A normal stress echocardiogram in LBBB is associated with benign prognosis while those with LBBB and abnormal SE have the worst outcomes.