Right Bundle Branch Block Patients Research Articles

Impact of Quantitative ST-T Analysis in Patients with Suspected Myocardial Infarction Presenting with Right Bundle Branch Block

BackgroundWhile left bundle branch block (LBBB) is a well-known risk feature in patients with acute myocardial infarction, and a rapid invasive management is recommended, data supporting this strategy for patients with right bundle branch block (RBBB) is less robust. MethodsIn total, 2139 patients with suspected ST-elevation myocardial infarction (STEMI) were triaged to acute coronary angiography based on a prehospital 12-lead electrocardiogram (ECG). Sensitivity and specificity for STEMI-ECG criteria were compared in RBBB and non-BBB patients. Adjusted hazard ratios for 1-year overall mortality were computed. ResultsSTEMI was adjudicated in 1832/2139 (85.6%) of all patients and in 102/117 (87.2%) of RBBB patients. ST-segment deviation followed typical ST-T patterns in most RBBB patients. Of 17 RBBB patients without significant ST changes, STEMI was adjudicated in 14 (82%). Diagnostic accuracy of STEMI criteria was comparable in RBBB and non-RBBB patients for inferior (sensitivity: 51.1% vs 59.1%, P = .14; specificity: 66.7% vs 52.1%, P = .33) and anterior STEMI (sensitivity: 35.2% vs 36.6%, P = .80; specificity: 58.3% vs 49.5%, P = .55). Diagnostic performance was lower for lateral STEMI in RBBB patients (sensitivity: 14.8% vs 4.4%, P = .001; specificity: 75.0% vs 98.4%, P < .001). Patients with RBBB had higher 1-year mortality compared with non-BBB patients (hazard ratio 2.3%; 95% confidence interval, 1.25-4.21. ConclusionECG criteria used for detection of STEMI showed comparable diagnostic accuracy in RBBB and non-BBB patients. However, STEMI was frequently present in RBBB patients not fulfilling diagnostic ECG criteria. RBBB patients showed poorer outcome after 1 year. Consequently, the presence of RBBB in suspected STEMI cases signifies a high-risk feature, aligning with established guidelines.

Abstract 14012: The Importance of Right Bundle Branch Block in Suspected ST-Elevation Myocardial Infarction is Independent of ST-T Deviations

Background: In patients with suspected acute coronary syndrome (ACS) and bundle branch block (BBB) an emergent invasive strategy is recommended. While left bundle branch block (LBBB) is a well-known high-risk feature in patients with acute myocardial infarction, data supporting this strategy for right bundle branch block (RBBB) are scarce. Hypothesis: RBBB poses a high-risk feature in suspected ST-elevation myocardial infarction (STEMI). Methods: 2,139 patients with suspected STEMI were triaged to acute coronary angiography based on a prehospital, tele-transmitted digital 12-lead ECG. All discharge diagnoses were independently adjudicated. Sensitivity and specificity for STEMI-ECG-criteria were compared in RBBB and non-BBB patients. Adjusted hazard ratios for 1-year overall mortality were computed. Results: STEMI was adjudicated in 1,832/2,139 (85.6%) of all patients and in 102/117 (87.2%) of RBBB patients. ST-segment deviation followed typical patterns in most RBBB patients (n=36 for anterior, n=49 for inferior and n=15 for lateral STEMI) and among these a final diagnosis of STEMI was adjudicated in 88. Out of 17 patients without significant ST-changes, 14 (82%) were adjudicated as STEMI. Diagnostic accuracy of STEMI-criteria was comparable in RBBB and non-RBBB patients for anterior (sensitivity: 51.1% vs 59.1%, p=0.14; specificity: 66.7% vs 52.1%, p=0.33) and inferior STEMI (sensitivity: 35.2% vs 36.6%, p=0.80; specificity: 58.3% vs 49.5%, p=0.55). There was a statistical difference for lateral STEMI (sensitivity: 14.8% vs 4.4%, p=0.001; specificity: 75.0% vs 98.4%, p=0.001). Patients with RBBB had significantly higher1-year mortality compared to non-BBB patients. Adjusted hazard ratio for 1-year mortality comparing RBBB to non-BBB patients was 2.3% (95% CI 1.25-4.21, p=0.007). Conclusion: ECG-criteria for the detection of STEMI show comparable diagnostic accuracy in RBBB and non-BBB patients. However, STEMI was frequently present in RBBB patients not fulfilling diagnostic ECG-criteria. In addition, RBBB-patients showed poorer outcome after 1 year. Our data therefore reinforce current guidelines in designating ACS patients with RBBB, independent of ST-T deviations, high-risk and candidates for acute invasive evaluation.

Differences in Electrical Delay Between the Mid-septum and Apex with the Right Ventricular Lead: Novel Implications for Pacemaker Sensing.

Ventricular sensing relies on the analysis of a local intracardiac electrogram in reference to the QRS on the surface electrocardiogram. If both signals do not coincide in time, there is a delay in sensing intrinsic ventricular activity. We evaluated possible differences in the electrical delay between the mid-septum and apex as determined by the right ventricular (RV) lead position using a pacing system analyzer (PSA) during conventional pacemaker implantation. Patients without significant heart disease and intrinsic atrioventricular conduction underwent their first Medtronic (Minneapolis, MN, USA) or Abbott (Chicago, IL, USA) dual-chamber pacemaker implantation with the RV lead first positioned at the apex and then subsequently at the mid-septum. Real-time ventricular sensing data were obtained through PSA to determine the electrical delay Q-VS value as the time difference between the QRS and the released RV-sensed event marker "VS." Among 212 patients, 139 had narrow QRS and 73 had complete right bundle branch block (RBBB). Overall, both narrow QRS and RBBB patients exhibited shorter Q-VS lengths at the mid-septum compared to the apex (50.4 ± 24.2 ms and 66.7 ± 32.3 ms vs. 63.9 ± 27.6 ms and 71.7 ± 32.2 ms; P < .0001 and P < .001, respectively). The Q-VS in patients with Abbott devices was significantly shorter compared to that in patients with Medtronic devices at both the mid-septum and the apex in both patient groups (P < .0001). In conclusion, RV lead positioning at the mid-septum is associated with a shorter electrical delay compared to positioning at the apex in both narrow QRS and RBBB patients.

QTc interval measurement in patients with right bundle branch block: A practical method.

Prolonging the QT interval in the right bundle branch block (RBBB) can create challenges for electrophysiologists in estimating repolarization time and eliminating the effect of depolarization changes on QT interval. In this study, we aimed to develop a practice formula to eliminate the effect of depolarization changes on QT interval in patients with RBBB. This prospective study evaluated accidentally induced RBBB in patients undergoing electrophysiological study. Two expert electrophysiologists recorded the ECG parameters, including QRS duration, QT interval, and cycle length, in the patients. The formula was developed based on QT interval differences (with and without RBBB) and its proportion to QRS. Additionally, the Bazzet, Rautaharju, and Hodge formulas were used to evaluate QTc. We evaluated 96 patients in this study. The mean QT interval without RBBB was 369.39 ± 37.38, reaching 404.22 ± 39.23 after inducing RBBB. ΔQT was calculated as 34.83 ± 17.61, and the ratio of ΔQT/QRS with RBBB was almost 23%. Our formula is: (QTwith RBBB - 23% × QRS). Subtraction of 25% instead of 23% seems more straightforward and practical. Our formula could also predict the QTc interval in RBBB based on the Bazzet, Rautaharju, and Hodge formulas. Previous formulas for QT correction were hard to apply in the clinical setting or were not specified for RBBB. Our new formula allows a rapid and practical method for QT correction in RBBB in clinical practice.

Prevalence of new Onset Right Bundle Branch Block in Acute Myocardial Infarction and its Coronary Angiographic Findings in Patients Attending NICVD

Background and Aim: Acute myocardial infarction patients with left and right bundle branch block significantly contributes to higher risk of mortality. Right bundle branch block (RBBB) has clinical implications in acute myocardial infarction setting. The present study aimed to determine the prevalence of new onset RBBB in acute myocardial infarction and its association with coronary angiographic findings. Methodology: This cross-sectional study was conducted on 82 acute myocardial infarction (AMI) patients in National Institute of Cardiovascular Diseases (NICVD), Karachi from January 2022 June 2022. Study protocol was approved from the institution research and ethical committee. All the patients of either gender with an age range 25 years to 85 years having acute myocardial infarction were included. Written informed consent was taken. Patients with previous RBBB, had implanted pacemaker, and presentation of symptoms &gt;24 hours were excluded. Detailed history and clinical examination of each individual was done. Patients’ angiographic findings after eligibility based on coronary angiography was done and recorded. All the data were entered into pre-designed profroma. SPSS version 26 was used for data analysis. Results: Of the total 82 AMI patients, there were 48 (58.5%) male and 34 (41.5%) females. Age-wise distribution of AMI patients were as follows; 17 (20.7%) 25-45 years, 28 (34.2%) 46-65 years, and 37 (45.1%) 66-85 years. The overall mean age was 54.62±6.82 years. The prevalence of new onset RBBB and without RBBB was 17 (20.7%) and 65 (79.3%) respectively. Of the 17 AMI with RBBB patients, the incidence of single vessel disease, double vessel disease, triple vessel disease, and left main stem disease was 3 (17.6%), 5 (29.4%), 6 (35.3%) and 3 (17.6%) respectively. Majority of patients aged 46 years to 65 years had RBBB in 9 (32.1%), followed by 6 (16.2%) in patients 66-85 years and 2 (11.8%) in patients aged 25-45 years. Conclusion: The present study concluded that the prevalence of new onset RBBB was 20.7% among acute myocardial infarction patients. The incidence of triple vessel disease was prominent in acute myocardial infarction patients with RBBB followed by double vessel disease. Also, elderly patients of acute myocardial infarction patients were more susceptible to RBBB than younger one. Keywords: Right bundle branch blockage, Acute myocardial infarction, Coronary angiography

Abstract 12220: Right Bundle Branch and Bifascicular Blocks: Insensitive Prognostic Indicators for Acute Myocardial Infarction

Introduction: The clinical significance of right bundle branch block (RBBB) or bifascicular block (BFB) in the setting of ST-elevation myocardial infarction (STEMI) is uncertain. Informed by studies demonstrating higher rates of complete occlusion of the infarct-related artery in patients presenting with RBBB, the latest guidelines on STEMI management suggest patients with persistent ischemic symptoms and RBBB be considered for emergent coronary angiography. However, there has been little study of the prognostic implication of either RBBB or BFB in the setting of undifferentiated acute chest pain, and even less of the degree of ST-elevation in concomitant RBBB. Methods and Results: A total of 7626 patient encounters presenting to the Baylor St. Luke’s Medical Center between July 2018 and July 2020 with a chief complaint of “chest pain” were identified via electronic health record query. Of these encounters, 211 (2.8%) patients were found to have RBBB. Of that cohort, 18 (8.5%) presented with acute coronary syndrome, with STEMI accounting for 6 (2.8%), non-STEMI 9 (4.3%), and unstable angina 3 (1.4%). New or presumed new RBBBs were found in 59 (28%) of total RBBB patients, of which only 5 (8.5%) were found to have acute coronary syndrome and only 2 (3.4%) STEMI specifically. Similarly, 90 (42.7%) patients with chest pain and RBBB were found to have a BFB. New or presumed new BFBs were found in 40 (19%) patients, of which only 4 (10%) were also found to have acute coronary syndrome. No patients with new-onset BFB had STEMI. Furthermore, real-time diagnosis of anterior STEMI was complicated in two patients presenting with acute coronary syndrome by the masking of ST elevation in leads V1-3 by concomitant RBBB. Conclusions: In a large cohort of undifferentiated patients who presented with chest pain and RBBB or BFB (regardless if new or presumed new), only a small fraction had acute coronary syndrome, and even fewer STEMI. These data suggest patients with undifferentiated chest pain and RBBB on ECG with clinical suspicion for acute myocardial infarction and any degree of ST-elevation in leads V1-3 be considered for emergent coronary angiography rather than RBBB or BFB without ST-segment elevation.

Comparative diagnostic and prognostic implications of right versus left bundle branch block in patients with suspected ST-segment elevation myocardial infarction

Abstract Background Current ESC guidelines on management of acute myocardial infarction in patients presenting with ST-segment elevation (STEMI) recommend emergent invasive management in patients with ischemic symptoms and bundle branch block (BBB). While left bundle branch block (LBBB) is a well-known high-risk feature in patients with acute myocardial infarction, data on the diagnostic and prognostic impact of right bundle branch block (RBBB) in comparison to LBBB in the context of STEMI are scarce. Methods A prospective cohort of 2,139 patients with suspected STEMI were triaged by the on-call cardiologist to acute coronary angiography based on a prehospital, tele-transmitted digital 12-lead electrocardiogram. All discharge diagnoses were independently adjudicated. The diagnostic accuracy of RBBB or LBBB was calculated. 30-day and 1-year all-cause mortality were from a central national registry and compared for LBBB, RBBB and patients without BBB using the Kaplan Meier method. Unadjusted and adjusted (age, sex, hypertension, hyperlipoproteinemia, smoking status and history of coronary artery disease) hazard ratios for 1-year mortality were calculated for both BBB-types. Results The final diagnosis of STEMI was adjudicated in 1,832/2,139 (85.6%) of patients. RBBB was present in 117 (5.5%), LBBB in 61 (2.9%) patients, respectively. Patients with BBB were older than non-BBB patients: Median age was 69.7 years in RBBB, 68.9 years in LBBB and 62.6 years in non-BBB patients. Comparing both BBB types, LBBB patients more often had prior heart failure (6.3% in RBBB vs 11.5% in LBBB), while RBBB patients more often developed cardiac arrest before angiography (15.3% vs 3.7% in RBBB and LBBB patients respectively) and more frequently revealed Thrombolysis in Myocardial Infarction (TIMI) grade flow of 0 (61.0% vs 47.2%, respectively). Specificity for the final diagnosis of STEMI was not significantly different in both BBB-types: 95.1% (95% CI 92.1–97.0) in RBBB versus 92.8% (95% CI 89.4–95.2) in LBBB patients (p=0.25). Patients with RBBB had significantly higher 30-day and 1-year mortality (Figure 1), while LBBB and non-BBB patients showed similar outcome. Unadjusted hazard ratio for 1-year mortality comparing RBBB to non-BBB patients was 3.35 (95% CI 2.11–5.34, p&amp;lt;0.001) and 1.4 (95% CI 0.57–3.44, p=0.46) when comparing LBBB to non-BBB patients. After adjustment hazard ratio for RBBB patients was 2.3 (95% CI 1.25–4.21, p=0.007). Conclusion In the context of suspected STEMI, RBBB is an ominous sign associated with adverse clinical features like cardiac arrest prior to PCI, TIMI grade 0 flow, compared to LBBB or non-BBB presenters. Consequently, RBBB patients had poorer outcome after 12 months. Our data therefore reinforce current guidelines in designating RBBB-patients as very high-risk, demanding immediate management and triage. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Regional Research Foundation in Region Sjaelland, Denmark

Comparison between conduction system pacing and cardiac resynchronization therapy in right bundle branch block patients.

A significant number of right bundle branch block (RBBB) patients receive cardiac resynchronization therapy (CRT), despite lack of evidence for benefit in this patient group. His bundle (HBP) and left bundle pacing (LBP) are novel CRT delivery methods, but their effect on RBBB remains understudied. We aim to compare pacing-induced electrical synchrony during conventional CRT, HBP, and LBP in RBBB patients with different conduction disturbances, and to investigate whether alternative ways of delivering LBP improve response to pacing. We simulated ventricular activation on twenty-four four-chamber heart geometries each including a His-Purkinje system with proximal right bundle branch block (RBBB). We simulated RBBB combined with left anterior and posterior fascicular blocks (LAFB and LPFB). Additionally, RBBB was simulated in the presence of slow conduction velocity (CV) in the myocardium, left ventricular (LV) or right ventricular (RV) His-Purkinje system, and whole His-Purkinje system. Electrical synchrony was measured by the shortest interval to activate 90% of the ventricles (BIVAT-90). Compared to baseline, HBP significantly improved activation times for RBBB alone (BIVAT-90: 66.9 ± 5.5 ms vs. 42.6 ± 3.8 ms, p < 0.01), with LAFB (69.5 ± 5.0 ms vs. 58.1 ± 6.2 ms, p < 0.01), with LPFB (81.8 ± 6.6 ms vs. 62.9 ± 6.2 ms, p < 0.01), with slow myocardial CV (119.4 ± 11.4 ms vs. 97.2 ± 10.0 ms, p < 0.01) or slow CV in the whole His-Purkinje system (102.3 ± 7.0 ms vs. 75.5 ± 5.2 ms, p < 0.01). LBP was only effective in RBBB cases if combined with anodal capture of the RV septum myocardium (BIVAT-90: 66.9 ± 5.5 ms vs. 48.2 ± 5.2 ms, p < 0.01). CRT significantly reduced activation times in RBBB in the presence of severely slow RV His-Purkinje CV (95.1 ± 7.9 ms vs. 84.3 ± 9.3 ms, p < 0.01) and LPFB (81.8 ± 6.6 ms vs. CRT: 72.9 ± 8.6 ms, p < 0.01). Both CRT and HBP were ineffective with severely slow CV in the LV His-Purkinje system. HBP is effective in RBBB patients with otherwise healthy myocardium and Purkinje system, while CRT and LBP are ineffective. Response to LBP improves when LBP is combined with RV septum anodal capture. CRT is better than HBP only in patients with severely slow CV in the RV His-Purkinje system, while CV slowing of the whole His-Purkinje system and the myocardium favor HBP over CRT.

Right ventricular lead sensing latency in pacemaker therapy.

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.

Right ventricular lead sensing latency in pacemaker therapy

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Pacemaker’s ventricular sensing function relies on the analysis of the intracardiac electrogram (EGM) including the timing of the intrinsic detection. The phenomenon of ventricular sensing latency refers to the gap of time by which the intrinsic signal gets delayed to be detected compared with the surface electrogram (ECG). A pacing system analyzer (PSA) unit is needed to record the EGM during pacemaker operation, which is expected to correspond to those taken following implantation. Purpose We sought to determine the latency period for sensing EGM by the right ventricular (RV) lead, either through the PSA or through the implanted pacemaker on the same patient. Methods Patients without significant heart disease and intrinsic atrioventricular conduction underwent conventional dual-chamber Medtronic or Abbott pacemaker implantation with the RV lead positioned on mid-septum. Real time sensing data was obtained through PSA and after pacemaker implantation. The RV lead sensing latency was defined as the time interval Q-VS measured from the beginning of QRS on ECG to the released ventricular sensed (VS) event marker on either device. Results Of 157 patients, 105 had narrow QRS (&amp;lt;120 ms) and 52 had wide QRS (≥120 ms) of right bundle branch block (RBBB). Both narrow QRS and RBBB patients had longer sensing latency through PSA (50.9 ± 24.2 ms and 67.8 ± 32.9 ms, respectively) than through pacemaker (18.2 ± 12.8 ms and 31.2 ± 14.8 ms, respectively, both p&amp;lt;0.001). RBBB patients had longer sensing latency compared with narrow QRS patients, either through PSA or through pacemaker (p&amp;lt;0.001). The sensing latency of Medtronic recipients was longer than those of Abbott in narrow QRS, but not in RBBB (p=0.03 and p=0.08, respectively). Conclusion We demonstrated longer RV lead sensing latency (1) through PSA than through the implanted pacemaker, (2) in RBBB than in narrow QRS, (3) in Medtronic pacemakers compared with Abbott pacemakers. Knowledge of the RV lead sensing latency helps optimization of atrioventricular delay and reduces unnecessary ventricular pacing.

Evaluation of the 2021 European Society of Cardiology guidelines in pre-existing right bundle branch block patients undergoing transcatheter aortic valve implantation with a balloon-expandable valve.

AimsThe 2021 European Society of Cardiology guidelines recommend early pacemaker implantation in pre-existing right bundle branch block (RBBB) patients who develop PR prolongation or QRS axis change after transcatheter aortic valve implantation (TAVI). We aimed to evaluate this recommendation in TAVI recipients with a balloon-expandable valve (BEV).Methods and resultsWe retrospectively reviewed 188 pre-existing RBBB patients without pre-existing permanent pacemaker (PPM) who underwent TAVI with a BEV at our institution in 2015–19. Patients who developed high-degree atrioventricular block (HAVB) during TAVI or within 24 h post-TAVI were excluded. Eligible patients were divided according to the guideline-directed criteria (ΔPR interval ≥20 ms and/or QRS axis change). Patients who met the criteria (n = 102, 54.3%), compared with those who did not (n = 86), had a higher prevalence of baseline right axis deviation and were more likely to have received a larger valve with greater oversizing. The 30-day delayed HAVB rate did not differ significantly between the groups (3.9% vs. 4.7%, P = 1.00; odds ratio = 0.84, 95% confidence interval = 0.20–3.45). There was also no significant difference in terms of death (5.0% vs. 8.4% at 1 year; overall log-rank P = 0.94) or a composite of death or PPM implantation (14.8% vs. 16.6% at 1 year; overall log-rank P = 0.94) during follow-up post-TAVI. The majority of PR prolongations (79.4%) and QRS axis changes (52.0%) regressed within the following 24 h.ConclusionThe present data did not demonstrate an association of significant changes in PR interval or QRS axis with heightened delayed HAVB risk in BEV recipients with pre-existing RBBB. Prospective studies are warranted to confirm these findings.

Prevalence and impact on prognosis of right-bundle branch block in patients with acute heart failure: Findings from the RICA registry

ObjectivesThis work aims to determine the prevalence, characteristics, and impact on prognosis of right bundle branch block (RBBB) in a cohort of acute heart failure (AHF) patients. MethodsWe prospectively analyzed 3,638 AHF patients included in the RICA registry (National Heart Failure Registry of the Spanish Internal Medicine Society). We independently analyzed the relationship between baseline and clinical characteristics and the presence of RBBB as well as the potential impact of RBBB on 1-year all-cause mortality and a composite endpoint of 90-day post-discharge hospitalization or death. ResultsThe prevalence of RBBB was 10.9%. Patients with RBBB were older, a higher proportion were male, had more pulmonary comorbidities, had higher left ventricular ejection fraction values, and had worse functional status. There were no differences in risk for patients with RBBB, with an adjusted hazard ratio (95% confidence interval) for 1-year mortality of 1.05 (0.83–1.32), and for the composite endpoint of 90-day post-discharge hospitalization or death of 0.97 (0.74–1.25). These results were consistent on the sensitivity analyses. ConclusionsFew patients with AHF present with RBBB, which is consistently associated with advanced age, male sex, pulmonary comorbidities, preserved left ventricular ejection fraction, and worse functional status. Nonetheless, after considering these factors, RBBB in AHF patients is not associated with worse outcomes.

Incidence and in-hospital outcomes of right bundle branch block in patients with ST elevation myocardial infarction undergoing primary angioplasty

The presence of right bundle branch block (RBBB) in patients with ST elevation myocardial infarction (STEMI) has been associated with poor outcomes. However, the clinical and angiographic impact of RBBB in patients undergoing primary angioplasty are poorly established. This study aimed to evaulate the incidence, clinical and angiographic impact of RBBB in patients with STEMI treated with primary percutaneous coronary intervention (PCI). We included 352 patients admitted for STEMI and managed with primary PCI. They were enrolled between January 2000 and March 2017 in Cardiology B department of Fattouma Bourguiba university hospital. The presence of RBBB was made by a systematic electrocardiogram at admission. Right bundle branch block was documented in 12 patients (3.4%). Patients with RBBB were older (Mean age = 68.3 ± 13.35 years versus 59.7 ± 11.4 years, P = 0.012). There was not difference between male and female. Diabetes and history of angina were significantly higher in patients with RBBB ( P < 0.001 for both). These patients presented more frequently anterior STEMI, congestive heart failure, cardiogenic shock at admission ( P < 0.001 for all) and ventricular arrythmias ( P = 0.029). On coronarography, RBBB patients had higher incidence of multivessel disease ( P = 0.032), initial TIMI flow ≤ 1 ( P = 0.024) and no-reflow after PCI ( P = 0.014). All cause in-hospital mortality was greater in patients with RBBB (25% vs. 11.7%, P < 0.001). On multivariate analysis, persistant RBBB emerged as an independent predictor of in-hospital death (Odd ratio= 1.6; CI = 95%: 1.12–3.43; P < 0.001). Although RBBB presents in only about 3.5% of patients with STEMI, it was associated with poor in-hospital prognosis and increased in-hospital mortality.

Relationship Between Procedural Right Bundle Branch Block and 1-Year Outcome After Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy - A Retrospective Study.

Alcohol septal ablation (ASA) is a treatment option in patients with drug-refractory symptomatic hypertrophic obstructive cardiomyopathy (HOCM). In many patients, right bundle branch block (RBBB) develops during ASA because septal branches supply the right bundle branch. However, the clinical significance of procedural RBBB is uncertain.Methods and Results:We retrospectively reviewed 184 consecutive patients with HOCM who underwent ASA. We excluded 40 patients with pre-existing RBBB (n=10), prior pacemaker implantation (n=15), mid-ventricular obstruction type (n=10), and those lost to follow-up (n=5), leaving 144 patients for analysis. Patients were divided into 2 groups according to the development (n=95) or not (n=49) of procedural RBBB. ASA conferred significant decreases in the left ventricular pressure gradient (LVPG) in both the RBBB and no-RBBB group (from 74±48 to 27±27 mmHg [P<0.001] and from 75±45 to 31±33 mmHg [P<0.001], respectively). None of the RBBB patients developed further conduction system disturbances. The percentage reduction in LVPG at 1 year after the procedure was significantly greater in the RBBB than no-RBBB group (66±24% vs. 49±45%; P=0.035). Procedural RBBB was not associated with pacemaker implantation after ASA, but was associated with reduction in repeat ASA (odds ratio 0.34; 95% confidence interval 0.13-0.92; P=0.045). Although RBBB frequently occurs during the ASA procedure, it does not adversely affect clinical outcomes.

Mechanisms of left ventricular dyssynchrony: A multinational SPECT study of patients with bundle branch block

BackgroundTo better understand the mechanisms of left ventricular (LV) mechanical dyssynchrony (LVMD), we explored the relative contributions of QRS duration (QRSd), LV ejection fraction (EF), volumes and scar to LVMD measured by gated single-photon emission tomography in a population of consecutive patients with left bundle branch block (LBBB) and right bundle branch block (RBBB) compared to controls. MethodsMyocardial perfusion imaging studies of 275 LBBB and 83 RBBB patients from three centers were analyzed. LVMD was defined as an abnormal phase bandwidth or phase standard deviation. Hospital and gender-specific normal values were obtained from 172 controls. ResultsThe prevalence of LVMD was 85 and 40% in LBBB and RBBB, respectively. Ejection fraction, scar severity, and LBBB morphology independently explained 70% of variance seen in PhaseBW. Ejection fraction had the highest area under the curve (AUC 0.918) in the receiver operating characteristics analysis of LVMD with an optimal cut-off of 47% (sensitivity 73% and specificity 98%). Notably, QRSd was not predictive. ConclusionLV mechanical dysfunction plays a greater role than conduction abnormality in the genesis of LVMD, a finding that is intriguing in the context of contemporary literature which suggests that QRSd is the parameter that is most predictive of CRT response.

Electromechanical delay by speckle-tracking echocardiography: a novel tool for distinguishing between Brugada syndrome and isolated right bundle branch block

Abstract Background The electrocardiographic (ECG) definition of Brugada syndrome (BS) can be challenging because benign ECG abnormalities, such as right bundle branch block (RBBB), may mimic pathological ECG characteristics of BrS. However, although myocardial delay and deformation can be quantified by advanced imaging, it has not yet been used to differentiate between BrS and RBBB. Purpose The aim of this study was to characterize the electro-mechanical behavior of the heart of patients with type-1 BrS and subjects with isolated complete RBBB in order to differentiate these conditions. Methods In this two-center study, 66 subjects were analyzed by standard and speckle-tracking echocardiography (STE): 22 type-1 BrS, 24 isolated complete RBBB, and 20 healthy subjects. The participants were not treated by any drug potentially influencing myocardial conduction. Results Standard echocardiographic parameters did not differ among the groups. STE demonstrated that right ventricular (RV) mechanical dispersion (MD) was greater in RBBB as compared to BrS and controls (p&amp;lt;0.05). In patients with isolated RBBB, the greatest delay of RV time-to-peak longitudinal strain (TTP) was found in RV free-wall basal segments. Mean absolute deviations of TTP calculated for each left ventricular (LV) region were greater in patients with RBBB as compared to those with BrS and to controls with a localisation of the delay in LV antero-septal, anterior, lateral, and infero-septal basal segments (figure 1). Conclusions Advanced echocardiographic techniques may help to differentiate between BrS and RBBB. Indeed, STE allows to identify an electro-mechanical conduction delay in RBBB patients that is not found in patients affected by type-1 BrS. Electromechanical delay by STE Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Italian Society of Cardiology

Timing and evolution of advanced conduction disturbances in patients with right bundle branch block undergoing transcatheter aortic valve replacement.

This study sought to determine the timing and evolution over time of advanced conduction disturbances (CDs) in patients with baseline right bundle branch block (RBBB) undergoing transcatheter aortic valve replacement (TAVR). One hundred and ten consecutive patients with pre-existing RBBB were included (out of 1341, 8.2%). All arrhythmias during the hospitalization period were recorded. Follow-up was performed at 30 days, 1 year, and yearly thereafter. Conduction recovery and ventricular pacing percentage (VPP) was evaluated at 30 days in those patients with permanent pacemaker implantation (PPMI). Sixty-one (55.5%) patients suffered advanced CDs [97% complete or high-degree atrioventricular block (CHB/HAVB)], and the vast majority (98%) occurred within the first 3 days post-procedure (intraprocedural: 85%). Fifty-two (47.3%) patients had PPMI (vs. 11.0% in non-RBBB patients, P < 0.001). Ventricular pacing percentage at 1 month was higher in patients with persistent-intraprocedural CHB/HAVB compared to those with transient-intraprocedural or post-procedural CHB/HAVB [99 (interquartile range, IQR 97-100)% vs. 72 (IQR 30-99)%, P = 0.02]. Complete recovery (VPP < 1%) was observed in only one patient (2%) with CHB/HAVB. After hospital discharge, no symptomatic bradyarrhythmias or sudden death occurred within 30 days. Patients with pre-existing RBBB exhibited a higher risk of PPMI at 4-year follow-up (26% vs. 8% in non-RBBB patients, P < 0.001). In patients with pre-existing RBBB, the vast majority of advanced CDs occurred within the 3 days following TAVR, and most did not recover at 1-month, particularly those with intra-procedural persistent CHB/HAVB. These results should help to determine the hospitalization length and timing of PPMI in RBBB patients undergoing TAVR.

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

BackgroundThe electrocardiographic (ECG) definition of Brugada syndrome (BS) can be challenging because benign ECG abnormalities, such as right bundle branch block (RBBB), may mimic pathological ECG characteristics of BrS. However, although myocardial delay and deformation can be quantified by advanced imaging, it has not yet been used to differentiate between BrS and RBBB. The aim of this study was to characterize the electro-mechanical behavior of the heart of patients with type-1 BrS and isolated complete RBBB in order to differentiate these conditions. MethodsIn this two-center study, 66 subjects were analyzed by standard and speckle-tracking echocardiography (STE): 22 type-1 BrS, 24 isolated complete RBBB, and 20 healthy subjects. The participants were not treated by any drug potentially influencing myocardial conduction. ResultsStandard echocardiographic parameters did not differ among the groups. The greatest right ventricular (RV) mechanical dispersion was found in RBBB. Mean absolute deviations (MADs) of time-to-peak longitudinal strain calculated for each left ventricular (LV) region were greater in patients with RBBB as compared to BrS (p < .01). No differences were found between BrS and controls (p = .36). MADs in the basal segments in RBBB group were greater than MADs found in BrS group and controls (37.3 ms vs. 26.7 ms and 29.0 ms, respectively, p < .05). The greatest differences were found in the antero-septal, anterior, lateral, and infero-septal basal segments. ConclusionsAdvanced echocardiographic techniques may help to differentiate between BrS and RBBB. Indeed, STE allows to identify an electro-mechanical conduction delay in RBBB patients that is not found in patients affected by type-1 BrS.

Electrical and mechanical dyssynchrony in patients with right bundle branch block

BackgroundThough fairly benign reputation, the right bundle branch block (RBBB) can cause left ventricular mechanical dyssynchrony (LVMD). Still, the relationship between electrical disturbance and LVMD is partly unclear among these patients. MethodsThirty patients with RBBB and 60 matching controls were studied with vector electrocardiography and myocardial perfusion imaging phase analysis. RBBB group was divided into those with and those without LVMD. ResultsPrevalence of LVMD among RBBB patients was 50% and among controls 22%. Odds ratio (OR) for LVMD in patients with RBBB vs controls without RBBB was 3.6 (95% CI 1.4 to 9.3). Ejection fraction (EF), end-systolic volume, the angle between QRS and T vectors, and the QRS angle in the sagittal plane were significantly different between RBBB patients with and without LVMD. The QRS duration was comparable in these groups. EF associated independently with LVMD, explaining 60% of its variation. A cut-off value of EF ≤ 55% detected LVMD in 100% specificity (sensitivity of 47%). ConclusionHalf of the patients with RBBB had LVMD. The OR for LVMD between RBBB and normal ECG was 3.6. It seems that EF, rather than electrical parameters, is the main determinant of LVMD. This information might be useful when evaluating indications for cardiac resynchronization therapy.

The QR-max index, a novel electrocardiographic index for the determination of left ventricular conduction delay and selection of cardiac resynchronization in patients with non-left bundle branch block.

Non-left bundle branch block (non-LBBB) remains an uncertain indication for cardiac resynchronization therapy (CRT). Non-LBBB includes right bundle branch block (RBBB) and non-specific LV conduction delay (NSCD), two different electrocardiogram (ECG) patterns which are not generally considered to be associated with LV conduction delay as judged by the invasive assessment of the Q-LV interval. We evaluated whether a novel ECG interval (QR-max index) correlated with the degree of LV conduction delay regardless of the type of non-LBBB ECG pattern, and could, therefore, predict CRT response. In 173 non-LBBB patients on CRT (92 NSCD, 81 RBBB), the QR-max index was measured as the maximum interval from QRS onset to R-wave offset in the limb leads. The correlation between QR-max index and Q-LV interval and the impact of the QR-max index on time to first heart failure hospitalization during 3-year follow-up were assessed. Q-LV correlated better with the QR-max index than with QRSd, particularly in the RBBB group (r= 0.91; p< 0.001 vs. r= 0.19; p< 0.089), while the correlations were r= 0.79 (p< 0.01) and r= 0.68 (p< 0.01), respectively, in the NSCD group. In both groups, the QR-max index was significantly more able than QRSd to identify CRT responders (AUC 0.825 vs. 0.576; p= 0.0008 in RBBB; AUC 0.738 vs. 0.701; p= 0.459 in NSCD). A QR-max index exceeding a cutoff value of 120ms was associated with CRT response, with predictive values of 86.8 and 81.4% in RBBB and NSCD, respectively. The QR-max index reflects the degree of LV electrical delay regardless of QRS duration in RBBB and NSCD patients and is a useful indicator of suitability for CRT in non-LBBB patients.