Right Bundle Branch Block Pattern Research Articles

Discrimination between ventricular tachycardia and wide-QRS preexcited tachycardia.

To develop a new algorithm to differentiate ventricular tachycardia (VT) from preexcited tachycardia (pre-ET) according to left bundle branch block (LBBB) and right bundle branch block (RBBB) patterns. This study included 67 electrocardiograms (ECGs) with VT and 63 ECGs with pre-ET, collected from our hospital and through PubMed. Of those, 64 were allocated to the derivation cohort and the rest to the validation cohort. The diagnoses of the ECGs were confirmed using an electrophysiological study. Parameters and classifiers from prior algorithms along with the propagation speeds in the early portion of the QRS complex (initial deflection index) in leads V1, V6, aVR, II, and III were manually measured. The performance of the new algorithm was compared with that of prior algorithms. The initial deflection index in lead III was the strongest predictor of pre-ET in LBBB-pattern wide-QRS tachycardia (p = 0.003, AUC 0.805). The initial deflection index in lead V1 was the most powerful predictor of pre-ET in RBBB-pattern wide-QRS tachycardia (p = 0.001, AUC 0.848). Compared to earlier algorithms, those using the initial deflection indexes: lead III in LBBB patterns (cutoff value >0.3) and lead V1 in RBBB patterns (cutoff value ≤0.48), demonstrated superior performance in screening VT, with AUC values of 0.828. The initial deflection indexes proved effective as discriminators between VT and pre-ET in the validation cohort. In LBBB-pattern wide-QRS tachycardia, the early propagation speed of pre-ET was faster than that in VT. Conversely, in RBBB-pattern wide-QRS tachycardia, it was slower.

Bilateral Bundle Branch Block.

Left bundle branch block (LBBB) and right bundle branch block (RBBB) are classic manifestations of bundle branch conduction disorders. However, a third form that is uncommon and underrecognized may exist that has features and pathophysiology of both: bilateral bundle branch block (BBBB). This unusual form of bundle branch block exhibits an RBBB pattern in lead V1 (terminal R wave) and an LBBB pattern in leads I and aVL (absence of S wave). This unique conduction disorder may confer an increased risk of adverse cardiovascular events. BBBB patients may be a subset of patients that respond well to cardiac resynchronization therapy.

Electrocardiographic characteristics of right-bundle-branch-block premature ventricular complexes predicting absence of left ventricular scar in athletes with apparently structural normal heart.

Left ventricular scar is an arrhythmic substrate that may be missed by echocardiography and diagnosed only by cardiac magnetic resonance (CMR), which is a time-consuming and expensive imaging modality. Premature ventricular complexes (PVCs) with a right-bundle-branch-block (RBBB) pattern are independent predictors of late gadolinium enhancement (LGE) but their positive predictive value is low. We studied which electrocardiographic features of PVCs with an RBBB pattern are associated with a higher probability of the absence of an underlying LGE. The study included 121 athletes (36 ± 16 years; 48.8% men) with monomorphic PVCs with an RBBB configuration and normal standard clinical investigations who underwent CMR. LGE was identified in 35 patients (29%), predominantly in those with PVCs with a superior/intermediate axis (SA-IntA) compared to inferior axis (IA) (38% vs. 10%, P = 0.002). Among patients with SA-IntA morphology, the contemporary presence of qR pattern in lead aVR and V1 was exclusively found in patients without LGE at CMR (51.0% vs. 0%, P < 0.0001). Among patients with IA, the absence of LGE correlated to a narrow ectopic QRS (145 ± 16 vs. 184 ± 27 msec, P < 0.001). Among athletes with apparently idiopathic PVCs with a RBBB configuration, the presence of a concealed LGE at CMR was documented in 29% of cases, mostly in those with a SA-IntA. In our experience, the contemporary presence of qR pattern in lead aVR and V1 in PVCs with RBBB/SA-IntA morphology or, on the other hand, a relatively narrow QRS in PVCs with an IA, predicted absence of LGE.

The impact of right bundle branch block and SIQIII-type patterns in determining risk levels in acute pulmonary embolism.

Background: Electrocardiography (ECG) findings in acute pulmonary embolism (PE) are known to be related to various right ventricular (RV) alterations. These abnormalities are not included in risk stratification algorithms despite emerging evidence of their association with patient outcomes. We aimed to analyze the impact of right bundle branch block (RBBB) and/or SIQIII patterns as indicators for determining the level of risk in patients with PE. Methods: We performed a retrospective cohort study including all patients with confirmed acute PE hospitalized from January 2008 to December 2019 in two tertiary care cardiology departments. The first ECG taken at admission was selected and the analysis focused on the presence of a complete or an incomplete RBBB and SIQIII-type patterns. Results: A total of 255 patients were divided into two groups: Group I (47.8%, n=122) included patients with PE without RBBB nor SIQIII patterns, and Group II (52.2%, n=133) included patients with RBBB and/or SIQIII patterns. Patients in group II presented significantly more frequently with acute right heart symptoms (45.1% vs. 18%, p<0.001) and cardiogenic shock at admission (31.6 vs. 4.1%, p<0.001). Echocardiographic parameters indicating right heart injury also occurred more significantly in group II patients (p<0.001). By univariate analysis, patients in group II were found to be significantly associated with in-hospital mortality (22.6 vs. 6.1%, p=0.002) and major cardiovascular events (MACEs) during hospitalization (43.3 vs. 13.7%, p<0.001). Multivariate logistic regression analysis identified five independent factors predictive of MACEs: SIQIII and/or RBBB, renal failure, positive troponin levels, RV dysfunction and right heart failure symptoms during initial presentation. Kaplan-Meier survival analysis identified the inclusion in Group II and the presence of SIQIII pattern as predictors of overall mortality (p<0.001). Conclusions: Our study suggests an important and independent prognostic value of RBBB and SIQIII patterns and their usefulness in determining the outcome of PE patients.

Comparison of his bundle pacing versus biventricular pacing in heart failure: a systematic review and meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Despite optimal medical treatment, the 5-years mortality and HF readmission rate was 75.3% and 48.5%, respectively. The current guidelines recommended cardiac resynchronization therapy (CRT) by implanting biventricular pacing (BVP) for specific group of patients with HF with reduced ejection fraction (HFrEF) in order to reduce the mortality and the risk of HF events by 34%. However, 20% to 40% patients might not respond or even get clinical deterioration after receiving such device. To overcome the non-responders, His bundle pacing (HBP) emerges recently as one of the therapeutic options. His bundle pacing implantation potentially results in the narrower QRS duration as well as more improvement in left ventricle (LV) function compared with BVP in patients with LBBB. On top of that, HBP might become a more cost-effective solution, compared to CRT, particularly for the majority of developing countries in Asia. Purpose We aim to elaborate the clinical efficacy of HBP in specific patients with HF, compared to BVP. This HBP was implanted either as a primary therapeutic strategy for CRT candidates or as a rescue strategy for BVP non-responders. Methods This study is registered. A structured search was conducted in Pubmed, Embase, and Clinicaltrial.gov. Inclusion criteria were: Age &amp;gt;18 years old, NYHA II-IV, QRS duration ≥120 milliseconds, and left (LBBB) or right bundle branch block (RBBB) morphology. The primary endpoints were change in QRS duration, improvement in LVEF, improvement in NYHA class, and cardiovascular (CV) event. Results A total of 8 final articles involving 361 HF patients were included for analysis, with a male preponderance. The QRS duration was significantly narrower in HBP (MD: -23.44; 95%CI -34.92 to -11.97; P&amp;lt;0.001) compared to BVP. There was no statistically significant LVEF improvement between HBP group and BVP group in HF patients who were CRT candidates (MD: 4.63; 95%CI -4.47 to 13.74; P=0.32). The improvement in NYHA class varied between studies. One study reported comparable improvement between HBP and BVP, while another study reported better improvement in HBP compared to BVP. In terms of CV outcome, there was no significant difference in CV hospitalization and mortality rate. Heart failure hospitalization occurred both in HBP and BVP group, but the difference was not significant between groups. Improvement in QRS duration, LVEF, and NYHA class occurred in both LBBB and RBBB. Conclusion(s) HBP provides better electrical resynchronization compared to BVP. Additionally, some degree of reverse LV remodelling was also observed in HBP group of patients with either LBBB and RBBB patterns. However, the benefits of HBP in reducing HF hospitalization and CV mortality remain indeterminate. Further RCTs with large samples are still required to evaluate the superiority of HBP, compared to BVP for CRT, in reducing mortality and HF hospitalization.

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Artificial intelligence for phenotyping tetralogy of Fallot patients from electrocardiographic recordings

Abstract Background Tetralogy of Fallot (ToF) remains associated with significant morbidity and mortality. Artificial intelligence (AI) is a viable tool for identifying markers: deep learning (DL) can be used to automate measurements on the ECG trace and dimensionality reduction (DR) algorithms can be used for grouping patients based on ECG, imaging and genetic markers. Such an AI-based pipeline can aid in phenotyping by identifying ECG characteristics that correlate with outcome. Methods A cohort of patients with ToF were recruited for the study (n=388). All patients underwent echo- and electrocardiographic exams, and had recorded information on outcome (death, heart failure [HF], history of ventricular tachycardia [VT] or atrial fibrillation [AF]), lifestyle and imaging markers (left ventricular ejection fraction [LVEF] or NYHA score, among others). The analysis of the population consisted in three steps (Figure 1A). Firstly, the ECG was delineated using a DL model to obtain the P, QRS and T onsets/offsets for all cardiac cycles [1]. Secondly, the most stable heartbeat was selected, based on their morphology, for their usage into a DR algorithm [2]. This algorithm allowed combining the information of the different ECG leads, to automatically assess inter-patient similarities. Thirdly, patients were clustered with respect to ECG morphology, as extracted in the previous step, and said clusters were correlated with outcome. Results AI allowed to identify a subset of patients with higher outcome risk (Figure 1A). The blue, green and red clusters contained patients with right bundle branch block (RBBB) but with different morphologies, whereas the orange cluster had a relatively normal morphology (no RBBB) and the lowest QRS width (Figure 1B). With respect to events (Table 1), the red cluster was correlated with a significantly increased risk of all-type negative outcome (36.94%, p-value &amp;lt;0.0001). The orange and red clusters had a higher occurrence of death and AF. The green, blue and red clusters had a higher density of patients with VT. Despite the red, blue and green clusters presenting RBBB and a wide QRS complex, these show very different event rates, hinting at morphology as key to stratify risk: the higher-risk red cluster showed more QRS fractionation and reduced QRS amplitude. Finally, it is important to note the good correspondence with events despite the low correlation with imaging markers (TAPSE, RV diameter), hinting at the complementariness of both modalities. Conclusion AI can help identify clinical markers of interest in patients with ToF, given its ability to agglomerate all morphological information in the different ECG leads. In this work, the ECG markers correlated with clinical data, allowing the identification of a subgroup with increased risk of outcome (death, VT, AF, HF). The analysis shows that a RBBB pattern and increased QRS width are not the sole factors that might affect outcome. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fundaciό La Maratό de TV3

Terminal end of retro-aortic root branch: An unrecognized origin for "proximal left anterior fascicle" premature ventricular complexes with narrow QRS duration.

Premature ventricular complexes (PVCs) with narrow QRS duration, inferior frontal plane QRS axis, and right bundle branch block (RBBB) pattern generally originate from the proximal segment of the left anterior fascicle (LAF). The purpose of this study was to investigate the exact origin of this category of PVCs. Twenty-two patients with assumed proximal LAF-PVCs were enrolled in the study. Detailed mapping of fascicular potentials (FPs) was performed during sinus rhythm (SR) and PVCs. During SR, a cluster of FPs could be found at the most superior portion of the left ventricle (LV). These FPs represented the terminal end of a discrete branch of the left fascicular system, which we named the "retro-aortic root branch" (RARB). The shortest distance between the proximal LAF and the terminal end of the RARB was 13.5 ± 4.2 mm. The earliest activation site (EAS) of PVCs in all patients were confirmed at the terminal end of the RARB, where the FP-V interval was 35.1 ± 4.3 ms during PVCs. The shortest distance from the right coronary cusp (RCC) to the EAS was 5.3 ± 3.5 mm. PVCs could be eliminated by ablation from the RCC in 45.5% (10/22) cases, in the remaining cases, ablation at the EAS in the LV endocardium successfully abolished PVCs. The terminal end of the retro-aortic root branch was the actual origin site for PVCs with inferior frontal plane axis, RBBB pattern and narrow QRS duration. Ablation in the RCC or at the EAS in the LV could both eliminate PVCs safely with high efficacy.

Prognostic role of serial electrocardiographic changes in patients with acute pulmonary embolism. Data from the Italian Pulmonary Embolism Registry

BackgroundThe prognostic role of serial electrocardiographic modifications in patients with acute pulmonary embolism (PE) have been poorly investigated. We evaluate the electrocardiographic changes in PE patients during their hospitalization and the prognostic role of such ECG modifications in respect to 30-day mortality in patients enrolled in the Italian Pulmonary Embolism Registry (IPER). MethodsSubjects enrolled into the IPER (September 2006–August 2010) were stratified according to their hemodynamic status, as high- (hemodynamically unstable) and non-high-risk (hemodynamically stable) patients. ECG features were analysed at three fixed time points: at presentation, on day 3 and at discharge. ResultsOverall, 687 patients (286 males, mean age 69.0 ± 15.5 years) were included in the study. Among these, 71 (10.3 %) were at high-risk. In these patients, multivariate analysis revealed that the persistence of right ventricular strain (RVS) after three days from hospitalization was a predictor of 30-day mortality [HRa: 2.78 (95 % CI: 1.05–7.31, p = 0.003)]. Moreover, the persistence of right bundle branch block (RBBB) [HRa: 2. 48 (95 % CI: 1.03–5.09, p = 0.002)], negative T waves in V1-V4 (NTWs) [HRa: 1.63 (95 % CI: 1.04–2.55), p < 0.0001] and qR complex in lead V1 [HRa: HR: 5.44, (95 % CI: 3.22–9.44, p < 0.0001)] were associated with an increased risk of 30-day mortality. When RBBB, NTWs and qR complex in V1 lead were present concomitantly, the 30-day risk of death resulted significantly higher [HR: 12.5 (95 % CI: 3.39–46.4,) p < 0.0001]. ConclusionsPersistence of RBBB, NTWs, and qR pattern in V1 lead at day 3 of hospitalization are independent prognostic factors of death within 30 days in high-risk acute PE patients. The prognostic power of any single ECG abnormality is lower compared to the combination of the three ECG variables.

Bilateral Bundle Branch Block.

Left bundle branch block (LBBB) and right bundle branch block (RBBB) are classic manifestations of bundle branch conduction disorders. However, a third form that is uncommon and underrecognized may exist that has features and pathophysiology of both: bilateral bundle branch block (BBBB). This unusual form of bundle branch block exhibits an RBBB pattern in lead V1 (terminal R wave) and an LBBB pattern in leads I and aVL (absence of S wave). This unique conduction disorder may confer an increased risk of adverse cardiovascular events. BBBB patients may be a subset of patients that respond well to cardiac resynchronization therapy.

Predictors of pacemaker implantation after TAVI in a registry including self, balloon and mechanical expandable valves.

The need for permanent pacemaker implantation (PPMI) is a burdensome complication of transcatheter aortic valve implantation (TAVI). The aim of our study was to evaluate different anatomical, clinical, electrocardiographic, and procedural variables associated with the development of conduction abnormalities after TAVI across the entire device spectrum.Single-center prospective cohort of consecutive patients who underwent TAVI since March 2017. Final cohort was studied to detect areas of calcium within aortic valve characterized by leaflet sector and region. Membranous septum (MS) length was assessed throughout a modified coronal view. Device selection and positioning were performed according to the operator criteria.Device selection and positioning were performed according to the operator criteria. From the 273 patients included, 57 underwent PPMI (20.8%). Univariate analysis determined right bundle branch block (RBBB), QRS duration, MS length and calcium within LVOT of non-coronary cuspid as independent predictors. After multivariable logistic regression, both RBBB (OR 6.138; 95% CI 1.23-30.73, P = 0.027) and MS length (OR 0.259; 95% CI 0.164-0.399, P < 0.005) emerged as statistically significant. As a model, they could predict PPMI in 88.7%, independently of which valve used. Youden index analysis yielded 7.69 mm as the optimal cut-off with a negative and positive predictive value of 94.7 and 71.9%, respectively.In our experience, both RBBB pattern and short membranous septum (< 8 mm) were strongly and independently associated with new permanent pacemaker implantation, regardless of the device type. Our findings suggest that this simple evolved measure of MS length may guide device selection and implantation technique and facilitate early discharge.

B-PO01-022 EXPLORING THE OPTIMAL PACING MODALITY IN PATIENTS WITH HIGH-GRADE ATRIOVENTRICULAR BLOCK AND RIGHT BUNDLE BRANCH BLOCK PATTERN: A PILOT STUDY

For patients with right bundle branch block (RBBB) pattern in ECG who need a high percentage of ventricular pacing, biventricular pacing showed limited benefits. To explore the optimal pacing modality in high-degree atrioventricular (AV) block and RBBB pattern. We assessed the feasibility and outcomes of different pacing approach in consecutive patients with high-degree AV block and RBBB pattern from July 2018 to Jan 2021. Trans-septal pacing was attempted in 51 patients (34 men, age 73±11 years) by capturing 1) His-bundle (HBP) (n=8); 2) left bundle branch (LBBP) (n=25); and 3) para-Hisian interventricular septum (IVS pacing) (n=18). The baseline QRS duration (QRSd) was 144±17ms, with no significant difference between groups. HBP could not correct the RBBB with an acceptable threshold and was abandoned for permanent pacing in 4 out of 8 cases. IVS pacing led to varied QRS configurations with the QRSd of 133±14 ms and the left ventricular activation time (LVAT) of 87±13 ms. Isolated LBBP (LBBPiso) produced an RBBB pattern with a QRSd of 124±13 ms (p<0.001 vs. the intrinsic, and p=0.049 vs. IVS pacing) and LVAT of 75±11 ms (p=0.004 vs. IVS pacing). When optimized with AV delay or bipolar setting, further reduced QRSd of 112±14 ms (p<0.001 vs. LBBPiso) and fading of RBBB was achieved. The pacing thresholds of LBBP decreased further during follow-up (0.6±0.2V/0.4ms vs. 0.8±0.2 V/0.4ms at implantation, p=0.009). In patients with high-degree AV block and RBBB pattern, LBBP combined with programmed optimization retained most electrical synchrony with satisfactory safety and might serve as a preferred pacing modality.

B-PO04-033 THE PACING SITE IS CLOSER TO THE LEFT VENTRICULAR SEPTAL ENDOCARDIUM DURING LEFT BUNDLE BRANCH PACING THAN DURING LEFT VENTRICULAR SEPTAL PACING

Left bundle branch pacing (LBBP) using a transventricular septal method has emerged as an effective approach to physiological pacing. However, differentiating between LBBP and left ventricular (LV) septal pacing (LVSP) remains a challenge because both modalities generate narrow paced QRS complexes, which present with a right bundle branch block (RBBB) electrocardiographic pattern. To compare the distance between the pacing lead tip and LV septal endocardium on echocardiography between patients who underwent successful LBBP and LVSP. Twenty-five consecutive patients (74.2±9.2 y, 60% male) with traditional indications for permanent cardiac pacing were included in this study. Unipolar pacing from final sites generated narrow QRS complexes with a RBBB pattern in all patients. Left bundle branch (LBB) potentials were recorded at the final pacing sites in the 17 patients who constituted the LBBP group. In the 8 patients in the LVSP group, LBB potentials were absent at the final pacing sites and the R-wave peak time in lead V5 was consistent at high and low outputs. Medtronic SelectSecure® 3830 pacing leads were used in all patients. After the procedures, a physician who was blinded to the group selection performed echocardiographic measurements of the distance between the lead tip and LV septal endocardium in all patients. The paced QRS duration was comparable between LBBP and LVSP group (102.4±15.9 ms vs. 113.7±21.1 ms, P=0.264). In the LBBP group, the interval from LBB potential to the onset of the QRS was 31.4±10.0 ms. The distance between the lead tip and LV septal endocardium was 0.4±0.6 mm in the LBBP group and 2.6±2.1mm in the LVSP group during the diastolic phase (P=0.004). During the systolic phase, the distance was 0.6±0.9 mm in the LBBP patients and 4.0±3.6 mm in the LVSP patients (P=0.004). The sensing amplitude identified during follow-up was 16.14±3.83 mV in the LBBP group and 8.98±1.94 mV in the LVSP group (P=0.001). The landing zone of the lead tip was much closer to the LV septal endocardium in patients who underwent LBBP than in those who underwent LVSP. Our study highlights the need for real-time intraprocedural monitoring of the distance between the lead tip and the LV septal endocardium in patients who undergo LBBP.

Right bundle branch block–type wide QRS complex tachycardia with a reversed R/S complex in lead V6: Development and validation of electrocardiographic differentiation criteria

Differentiation of supraventricular tachycardia (SVT) with a right bundle branch block (RBBB) pattern from ventricular tachycardia (VT) is difficult, particularly when the R/S ratio in lead V6 is below 1.0. We sought to investigate the electrocardiographic criteria for distinguishing between these arrhythmias. We investigated electrocardiographic parameters from 111 consecutive patients who had RBBB pattern wide QRS complex tachycardia with a reversed R/S ratio in lead V6 (72 VTs, 39 SVTs). Diagnostic criteria from the previous algorithms were compared with our new criterion, the RS/QRS ratio, which was defined as the ratio of the interval from the onset of the QRS complex to the nadir of the S wave, divided by the QRS width in lead V6. The RS/QRS ratio was further tested in a prospective population (31 fascicular VTs, 29 SVTs). The diagnostic accuracy of previous criteria (Brugada algorithm, Vereckei algorithm, and R-wave peak time criterion) was only modest. However, the RS/QRS ratio in lead V6 was significantly lower in SVT than in VT (0.36 ± 0.04 vs 0.50 ± 0.08; P < .001). A cutoff value of the RS/QRS ratio >0.41 differentiated VT from SVT with a high diagnostic accuracy (sensitivity 97.2%; specificity 89.7%). When tested in a prospective population with fascicular VT, the diagnostic accuracy of the criteria was maintained (sensitivity 90.3%; specificity 86.2%). The RS/QRS ratio >0.41 in lead V6 is a simple and reliable index for distinguishing VT from SVT in RBBB pattern wide QRS complex tachycardia with a reversed R/S complex in lead V6. This criterion was particularly useful for the differential diagnosis of fascicular VT from RBBB pattern SVT.

ECG clues for false ST-segment elevation myocardial infarction activations

Rapid diagnosis of ST-segment elevation myocardial infarction (STEMI) is crucial for appropriate management. Catheterization for a false STEMI activation has risks including exposure to contrast agent and radiation, increased healthcare costs and delay in treatment of the primary medical condition. This was a single center retrospective study including all 'cath alerts' between January 2012 and December 2015. 'Cath alert' is a term used to activate the interventional cardiology team when STEMI is suspected by the emergency department physicians based on review of the initial ECG. We reviewed all STEMI alerts to understand ECG differences between true and false STEMI. Our study population (N = 361) included 221 (61%) men and 140 (39%) women, with average age 60 ± 4.2 years. Among the 361 STEMI alerts, 82 (22.7%) did not have acute coronary syndrome. Common ECG causes of misdiagnosis included left ventricular hypertrophy (LVH, found in 40/82, 49%), early repolarization changes (20/82, 24%), right bundle branch block (RBBB) (13/82, 16%), and Brugada pattern (3/82, 4%). Multivariate regression analysis showed that LVH and RBBB were independent predictors of nonacute coronary syndrome false STEMI (odds ratio: 0.54; 95% confidence interval: 0.32-0.93; P = 0.03 for LVH, and odds ratio: 0.26, 95% confidence interval: 0.1-0.62, P = 0.004 for RBBB). The incidence of false STEMI alerts was almost 23% at our center. This number might be reduced with additional training of emergency department physicians in ECG interpretation, and recognition of common causes of misdiagnosis such as LVH, early repolarization changes, RBBB, and Brugada pattern.

The characteristics of the electrocardiogram and the intracardiac electrogram in left bundle branch pacing.

Left bundle branch pacing (LBBP) has recently been reported to maintain left ventricular electrical synchrony with a low and stable threshold. However, the electrocardiogram (ECG) definitions of LBBP have not been well established. We report four cases to show the characteristics of the ECG and the intracardiac electrogram (EGM) in LBBP. Four patients, two with an atrioventricular block (AVB) and two with left bundle branch block (LBBB), were included in the study. LBBP was performed and the ECGs and EGMs were collected and compared at different pacing outputs. Selective LBBP (S-LBBP) was defined as only capturing the LBB with a typical RBBB morphology and a discrete component between the pacing stimulus and ventricular activation in the EGMs. While nonselective LBBP (NS-LBBP) captured both the LBB and the local myocardium, resulting in a narrow right bundle branch block (RBBB) morphology without the discrete component. The left bundle branch (LBB) potential was recorded in two cases during narrow QRS complex or LBBB correction by selective His bundle pacing and SLBBP (n = 3) was achieved. A constant and shortest stimulus to left ventricular activation time (LVAT) in LBBP was obtained at different pacing outputs. The ECG and EGM characteristics of LBBP can be summarized as: 1) RBBB pattern; 2) usually with the LBB potential; 3) SLBBP with specific ECG changes and a discrete component in EGM; and 4) with a constant and shortest stimulus to LVAT at different pacing outputs. Further studies are necessary to confirm these observations.

Patients with right bundle branch block and concomitant delayed left ventricular activation respond to cardiac resynchronization therapy.

Right bundle branch block (RBBB) typically presents with only delayed right ventricular activation. However, some patients with RBBB develop concomitant delayed left ventricular (LV) activation. Such patients may show a specific electrocardiographic (ECG) pattern resembling RBBB in the precordial leads in association with an insignificant S-wave in lateral limb leads (atypical RBBB). We therefore postulated that the ECG pattern of atypical RBBB might be able to identify a subgroup of patients likely to respond to cardiac resynchronization therapy (CRT). The purpose of this study was to assess the impact of RBBB ECG morphology on CRT response in patients with heart failure (HF). We evaluated the echocardiographic clinical response of 66 patients with RBBB treated with CRT and followed up for almost 2 years. The patients were divided electrocardiographically into 2 groups: 31 with typical RBBB and 35 with atypical RBBB. Responders were classified in terms of reduction in LV end-systolic volume index (ESVi) ≥ 15% or reduction in the New York Heart Association (NYHA) Class ≥ 1 or Packer score variation (NYHA response with no HF-related hospitalization events or death). The atypical RBBB group presented a longer LV activation time compared with the typical RBBB group (111.9 ± 17.6 vs. 73.2 ± 15.4 ms; P < 0.001). In the atypical and typical RBBB groups, respectively, 71.4% and 19.4% of patients were ESVi responders (P = 0.001) 74.3% and 32.3% were NYHA responders (P = 0.002); similarly, 71.4% and 29.0% of patients exhibited a 2-year Packer score of 0 (P = 0.002). Patients with atypical RBBB, which is a pattern highly suggestive of concomitant delayed LV conduction, may show a satisfactory response to CRT.

The relevance of looking for right bundle branch block in catheter ablation of Ebstein's anomaly

IntroductionEbstein's anomaly is the most commonly occurring congenital defect associated with the Wolff-Parkinson-White syndrome. In patients with Ebstein's anomaly and supraventricular tachycardia, the absence of right bundle branch block (RBBB) in sinus rhythm is a highly sensitive and specific indicator of the presence of an ipsilateral accessory AP. CaseWe present an electrophysiology case of a patient with Ebstein's anomaly and 3 ipsilateral accessory pathways. After ablation was performed, RBBB was evident. ConclusionIn patients with Ebstein's anomaly and supraventricular tachycardia, the absence of a RBBB pattern in the surface ECG after RFCA should raise suspicion for the presence of multiple accessory pathways.

Right bundle branch block and SIQIII-type patterns for risk stratification in acute pulmonary embolism

IntroductionRisk stratification in acute pulmonary embolism (PE) is crucial for identification of patients with poor prognosis. We aimed to investigate the ECG alterations of right bundle branch block (RBBB) and SIQIII-type patterns for risk stratification in acute PE. Materials and methodsRetrospective analysis of PE patients, treated in the Internal Medicine Department, was performed. Patients with RBBB and/or SIQIII-type were compared with those without both patterns. Logistic regression models for association between these ECG alterations and respectively right ventricular dysfunction (RVD), high-risk PE status and myocardial injury were computed. Results175 patients were included for this retrospective analysis. Total study sample comprised 37 PE patients (21.1%) with RBBB and/or SIQIII-type patterns and 138 PE patients (78.9%) without both signs.Heart rate (97.4±17.2 vs. 93.2±26.8/min, P=0.021), cardiac troponin I values (0.19±0.38 vs. 0.11±0.24, P=0.003) and percentage of patients with RVD (83.9% vs. 52.7%, P=0.005) were significantly higher in PE patients with RBBB and/or SIQIII-type patterns compared to PE patients without both ECG alterations.Multi-variate logistic regression models adjusted for age and gender revealed significant associations between RBBB and RVD (OR3.942, 95% CI1.054–14.747, P=0.042) and between SIQIII-type patterns and RVD (OR5.667, 95% CI1.144–28.071, P=0.034). The association between RBBB and cardiac injury (cTnI>0.4ng/ml) (OR2.531, 95% CI 0.973–6.583, P=0.06) showed a borderline significance, while the association between SIQIII-type patterns and cardiac injury was significant (OR3.956, 95% CI1.309–11.947, P=0.015). ConclusionsRBBB and SIQIII-type patterns were both associated with RV overload and cardiac injury. RBBB and SIQIII-type patterns were connected with 3.9-fold and 5.7-fold elevated risk of RVD, respectively.

Left Dominant Arrhythmogenic Cardiomyopathy Causing Sustained Ventricular Tachycardia – A Case Report

A 56-year-old white man was admitted to hospital because of palpitations and dyspnoea. He had no family history of cardiomyopathy or sudden death, and the electrocardiograms (ECG) of his son and parents were normal. He had an history of palpitations, and in the emergency department ECG showed sustained ventricular tachycardia-flutter with inferior axis right bundle branch block (RBBB) in V1 and heart rate 250 beats per minute. His standard ECG showed a complete RBBB pattern with minor ST-T segment changes. 2D echo and coronary angiography were normal, while magnetic resonance imaging (MRI) revealed a reduction in left mid-lateral wall thickening with hypokinetic movement and mild reduction of ejection fraction. An Extensive sub-epicardial area of conspicuous left ventricular intra-myocardial fat and sub-epicardial left ventricular late enhancement in lateral wall, was also seen at MRI. No abnormalities of right ventricular size, function or tissue characterisation were detected. A diagnosis of atypical left dominant arrhythmogenic cardiomyopathy was made, based on clinical and images basis, as gene testing was not available.