Risk of mortality associated to chronic kidney disease in patients with complete left bundle branch block.

Chronic kidney disease (CKD) is associated with cardiac conduction defects and is a strong risk factor for heart failure. Complete left bundle branch block (cLBBB), a cardiac conduction abnormality, may have an unfavorable effect on ventricular mechanical synchrony and lead to the progression of heart failure. Once heart failure develops, it seems to act together with underlying CKD in a vicious circle. Therefore, this study aimed to explore the influence of CKD in patients with cLBBB by assessing the estimated glomerular filtration rate (eGFR). We examined a hospital-based sample of 416 adult patients with cLBBB from 2010 to 2013. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Cox proportional hazard models were used to estimate the hazard ratio for all-cause mortality and cardiovascular mortality. A total of 416 adult patients with a mean age of 71 ± 13 years were enrolled. The median follow-up period was 3.6 years. After adjusting for clinical, electrocardiographic parameters, and medication use, cox regression analysis showed that total mortality was significantly associated with older age (Hazard Ratio (HR) = 1.03, 95% CI = 1.01-1.05, p = 0.002), presence of congestive heart failure (HR = 2.39, 95% CI = 1.63-3.49, p < 0.001), advanced CKD (HR = 2.48, 95% CI = 1.71-3.59, p < 0.001), higher HR (HR = 1.02, 95% CI = 1.01-1.03, p < 0.001) and without use of ACEI/ARB (HR = 0.59, 95% CI = 0.41-0.85, p = 0.005) were independent predictors of the total mortality. Multivariate Cox hazard regression analysis demonstrated that, in comparison to patients lacking cLBBB, the coexistence of CKD (eGFR < 60 mL/min/1.73 m2) among those with LBBB significantly heightened the risks of both total mortality (HR ratio of 5.01 vs. 2.40) and CV death (HR ratio of 61.78 vs. 14.41) even following adjustment for clinical covariates and ECG parameters. In summary, within patients exhibiting cLBBB, the presence of CKD serves as a significant risk factor for all-cause mortality.

Left bundle branch area pacing in heart failure: A systematic review and meta-analysis with meta-regression.

INTRODUCTION: Left bundle branch area pacing is an alternative to biventricular pacing. In this study, we aim to summarize the available evidence on the feasibility, efficacy, and safety of left bundle branch block area pacing (LBBAP). OBJECTIVES: The study summarizes the available evidence on the feasibility, efficacy, and safety of left bundle branch block area pacing (LBBAP). BACKGROUND: Cardiac resynchronization therapy (CRT) reduced mortality and hospitalizations in heart failure (HF) patients with a left ventricular ejection fraction (LVEF) ≤ 35% and concomitant LBBB. Recently LBBAP has been studied as a more physiological alternative to achieve CRT. METHOD: A search of PubMed, EMBASE, and Cochrane databases were performed to identify studies examining the role of LBBAP for CRT in heart failure. Comprehensive meta-analysis version 4 was used for meta-regression to examine variables that contribute to data heterogeneity. RESULT: Eighteen studies, 17 observational and one randomized controlled trial (RCT) were examined. A total of 3906 HF patients who underwent CRT (2036 LBBAP vs. 1870 biventricular pacing [BVP]) were included. LBBAP was performed successfully in 90.4% of patients. Compared to baseline, LBBAP was associated with a reduction in QRS duration (MD: -47.23 ms 95% confidence interval [CI]: -53.45, -41.01), an increase in LVEF (MD: 15.22%, 95% CI: 13.5, 16.94), and a reduction in NYHA class (MD: -1.23, 95% CI: -1.41, -1.05). Compared to BVP, LBBAP was associated with a significant reduction in QRS duration (MD: -20.69 ms, 95% CI: -25.49, -15.88) and improvement in LVEF (MD: 4.78%, 95% CI: 3.30, 6.10). Furthermore, LBBAP was associated with a significant reduction in HF hospitalization (odds ratio [OR]: 0.44, 95% CI: 0.34, 0.56) and all-cause mortality (OR: 0.67, 95% CI: 0.52, 0.86) compared to BVP. CONCLUSION: LBBAP was associated with improved ventricular electrical synchrony compared to BVP, as well as better echocardiographic and clinical outcomes.

Clinical significance and prognostic value of right bundle branch block in permanent pacemaker patients.

AIMS: In patients undergoing pacemaker implantation with no prior history of heart failure (HF), the presence of left bundle branch block (LBBB) has been identified as an independent predictor of HF-related death or hospitalization, while the prognostic significance of right bundle branch block (RBBB) remains uncertain. We aimed to assess the long-term risk of all-cause mortality in patients with a standard indication for permanent pacing and normal or moderately depressed left ventricular function when RBBB is detected at the time of implantation. METHODS: We retrospectively enrolled 1348 consecutive patients who had undergone single- or dual-chamber pacemaker implantation at the study center, from January 1990 to December 2022. Patients with a left ventricular ejection fraction ≤35% or a prior diagnosis of HF were excluded. RESULTS: The baseline 12-lead electrocardiogram revealed an RBBB in 241 (18%) and an LBBB in 98 (7%) patients. During a median follow-up of 65 [25th-75th percentile: 32-117] months, 704 (52%) patients died. The combined endpoint of cardiovascular death or HF hospitalization was reached by 173 (13%) patients. On multivariate analysis, RBBB was confirmed as an independent predictor of death [hazard ratio, 1.33; 95% confidence interval (CI), 1.09-1.63; P  = 0.005]. However, when considering the combined endpoint of cardiovascular death and HF hospitalization, this endpoint was independently associated with LBBB (hazard ratio, 2.13; 95% CI, 1.38-3.29; P  < 0.001), but not with RBBB. CONCLUSION: In patients with standard pacemaker indications and normal or moderately depressed left ventricular function, the presence of basal RBBB was an independent predictor of mortality. However, it was not associated with the combined endpoint of cardiovascular death and HF hospitalization.

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

BACKGROUND: While 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. METHODS: In 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. RESULTS: STEMI 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. CONCLUSION: ECG 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.

Improved all-cause mortality with left bundle branch area pacing compared to biventricular pacing in cardiac resynchronization therapy: a meta-analysis.

BACKGROUND: Left bundle branch area pacing (LBBAP) has emerged as a physiological alternative pacing strategy to biventricular pacing (BIVP) in cardiac resynchronization therapy (CRT). We aimed to assess the impact of LBBAP vs. BIVP on all-cause mortality and heart failure (HF)-related hospitalization in patients undergoing CRT. METHODS: Studies comparing LBBAP and BIVP for CRT in patients with HF with reduced left ventricular ejection fraction (LVEF) were included. The coprimary outcomes were all-cause mortality and HF-related hospitalization. Secondary outcomes included procedural and fluoroscopy time, change in QRS duration, and change in LVEF. RESULTS: Thirteen studies (12 observational and 1 RCT, n = 3239; LBBAP = 1338 and BIVP = 1901) with a mean follow-up duration of 25.8 months were included. Compared to BIVP, LBBAP was associated with a significant absolute risk reduction of 3.2% in all-cause mortality (9.3% vs 12.5%, RR 0.7, 95% CI 0.57-0.86, p < 0.001) and an 8.2% reduction in HF-related hospitalization (11.3% vs 19.5%, RR 0.6, 95% CI 0.5-0.71, p < 0.00001). LBBAP also resulted in reductions in procedural time (mean weighted difference- 23.2 min, 95% CI - 42.9 to - 3.6, p = 0.02) and fluoroscopy time (- 8.6 min, 95% CI - 12.5 to - 4.7, p < 0.001) as well as a significant reduction in QRS duration (mean weighted difference:- 25.3 ms, 95% CI - 30.9 to - 19.8, p < 0.00001) and a greater improvement in LVEF of 5.1% (95% CI 4.4-5.8, p < 0.001) compared to BIVP in the studies that reported these outcomes. CONCLUSION: In this meta-analysis, LBBAP was associated with a significant reduction in all-cause mortality as well as HF-related hospitalization when compared to BIVP. Additional data from large RCTs is warranted to corroborate these promising findings.

Cardiac resynchronization therapy in acute heart failure and left bundle-branch block in a real-life registry.

Objectives: To determine the prevalence, characteristics, timing of implementation and prognosis of patients with left bundle branch block (LBBB) and acute heart failure (AHF) treated with cardiac resynchronization therapy (CRT) in a real-life registry. Methods: We analysed the characteristics of patients with AHF and LBBB at the time of inclusion in the EAHFE (Epidemiology Acute Heart Failure Emergency) cohort to determine the indication for CRT, the timing of implementation and its impact on 10-year all-cause mortality. Results: 729 patients with a median age of 82 years and there was a high burden of comorbidities and functional dependence. The median left-ventricle ejection fraction (LVEF) was 40%. Forty-six (6%) patients were treated with CRT at some point during follow-up, with a median time of delay for CRT implementation of 960 (IQR=1,147 days) and at least 108 more untreated patients fulfilled criteria for CRT. Patients receiving CRT were younger, had different comorbidities, less functional dependence (higher Barthel index) and lower LVEF values. The median follow-up was 5.7 years (95% CI: 5.6-5.8) and CRT was not associated with changes in 10-year mortality (adjusted HR 1.33, 95% CI: 0.72-2.48; p-value 0.4). When compared with untreated patients fulfilling criteria for CRT, very similar results were observed (adjusted HR 1.34, 95% CI: 0.67-2.68). Conclusions: CRT implementation was delayed and underused in patients with AHF and LBBB. Under these circumstances, CRT is not associated with a reduction in all-cause mortality in the long term.

Objetivos: Determinar la prevalencia, características, momento de implantación y pronóstico de los pacientes con bloqueo de rama izquierda del haz de His (BRIHH) e insuficiencia cardiaca aguda (ICA) tratados con terapia de resincronización cardiaca (TRC) en un registro real. Métodos: Se analizaron las características de los pacientes con ICA y BRIHH en el momento de su inclusión en la cohorte EAHFE (Epidemiology Acute Heart Failure Emergency) para determinar la indicación de TRC, el momento de implantación y su impacto en la mortalidad por cualquier causa a 10 años. Resultados: 729 pacientes con una mediana de edad de 82 años con una elevada carga de comorbilidades y dependencia funcional. La mediana de la fracción de eyección del ventrículo izquierdo (FEVI) fue del 40%. 46 pacientes (6%) fueron tratados con TRC en algún momento del seguimiento, con una mediana de tiempo de retraso para la implantación de la TRC de 960 dias (IQR=1,147 días) y al menos 108 pacientes no tratados cumplían criterios para TRC. Los pacientes que recibieron TRC eran más jóvenes, tenían comorbilidades diferentes, menor dependencia funcional (índice de Barthel más alto) y valores de FEVI más bajos. La mediana de seguimiento fue de 5.7 años (IC del 95%: 5.6-5.8) y la TRC no se asoció a cambios en la mortalidad a 10 años (HR ajustado: 1.33; IC del 95%: 0.72-2.48; p-valor 0.4). Cuando se comparó con pacientes no tratados que cumplían criterios para TRC, se observaron resultados muy similares (HR ajustado 1.34; IC del 95%: 0.67-2.68). Conclusiones: La implantación de la TRC se retrasó y se infrautilizó en pacientes con ICA y BRIHH. En estas circunstancias, la TRC no se asocia a una reducción de la mortalidad por cualquier causa a largo plazo.

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.

Fascicular heart blocks and risk of adverse cardiovascular outcomes: Results from a large primary care population.

BACKGROUND: Fascicular heart blocks can progress to complete heart blocks, but this risk has not been evaluated in a large general population. OBJECTIVE: The purpose of this study was to investigate the association between various types of fascicular blocks diagnosed by electrocardiographic (ECG) readings and the risk of incident higher degree atrioventricular block (AVB), syncope, pacemaker implantation, and death. METHODS: We studied primary care patients referred for ECG recording between 2001 and 2015. Cox regression models were used to estimate hazard ratios (HRs) as well as absolute risks of cardiovascular outcomes. RESULTS: Of 358,958 primary care patients (median age 54 years; 55% women), 13,636 (3.8%) had any type of fascicular block. Patients were followed up to 15.9 years. We found increasing HRs of incident syncope, pacemaker implantation, and third-degree AVB with increasing complexity of fascicular block. Compared with no block, isolated left anterior fascicular block (LAFB) was associated with 0%-2% increased 10-year risk of developing third-degree AVB (HR 1.6; 95% confidence interval [CI] 1.25-2.05), whereas right bundle branch block combined with LAFB and first-degree AVB was associated with up to 23% increased 10-year risk (HR 11.0; 95% CI 7.7-15.7), depending on age and sex group. Except for left posterior fascicular block (HR 2.09; 95% CI 1.87-2.32), we did not find any relevant associations between fascicular block and death. CONCLUSION: We found that higher degrees of fascicular blocks were associated with increasing risk of syncope, pacemaker implantation, and complete heart block, but the association with death was negligible.

Right bundle branch block is not associated with worse short- and mid-term outcome after transcatheter aortic valve implantation.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) is the standard treatment option for patients with severe aortic stenosis (AS) at intermediate or high surgical risk. Preexisting right bundle branch block (RBBB) is a strong predictor of new pacemaker implantation (PPM) after TAVI, and previous data indicate a worse short- and long-term outcome of patients. The aim of this study was to investigate whether preexisting RBBB has an effect on the short- and mid-term outcome of patients undergoing TAVI in a German high-volume TAVI center. METHODS: For the present retrospective analysis, a total of 1,891 patients with native severe AS with successful TAVI without preexisting PPM were included. The primary endpoint was all-cause mortality after 30 days and 12 months. Baseline RBBB was present in 190 (10.1%) of cases. RESULTS: Patients with preexisting RBBB had a considerably higher rate of new PPM after TAVI compared with patients without RBBB (87/190 [45.8%] vs. 219/1,701 [12.9%]; p<0.001). RBBB had no impact on all-cause mortality at 30 days (2.1% vs. 2.7%; p = 0.625) and at 12 months (14.4% vs. 13.6%; p = 0.765). Further stratification according to the presence of new PPM showed a difference in mid-term survival rates between the four groups, with the worst outcome for patients without RBBB and new PPM (log rank p = 0.024). However, no difference in mid-term cardiovascular survival was found. CONCLUSION: Preexisting RBBB is a common finding in patients with severe AS undergoing TAVI and is associated with considerably higher PPM rates but not with worse short- and mid-term outcome.

Prevalence, Incidence and Prognostic Implications of Left Bundle Branch Block in Patients with Chronic Coronary Syndromes (From the CLARIFY Registry).

Left Bundle Branch Block (LBBB) is a frequently encountered electrical abnormality in patients with chronic (more than 3 months after myocardial infarction, or evidence of coronary artery disease with ischemia) coronary syndromes (CCS), but its prognostic significance remains unclear. We aimed to describe the prevalence, incidence and five-year outcomes of LBBB in outpatients with CCS using the CLARIFY registry. Main outcome was a composite of CV death, MI or stroke. Secondary outcomes included all cause death, hospitalization for heart failure (HF) and permanent pacemaker implantation. Among 23.544 patients with available information regarding LBBB status at baseline, 1.041 (4.4%) had LBBB at baseline and 1.015 (4.5%) patients developed a new LBBB during 5-year follow-up. In multivariate analysis, LBBB at baseline was not associated with the composite outcome of CV death, MI or stroke (HR 1.06, 95% CI [0.86 - 1.31], p = 0.67) or the risk of all-cause death (HR 1.07, 95% CI [0.87 - 1.32], p = 0.52) but was significantly associated with a higher risk of hospitalization for HF (HR 1.50, 95% CI [1.21 - 1.88], p < 0.001) and permanent pacemaker implantation (HR 2.11, 95% CI [1.45 - 3.07], p < 0.001). The main factors associated with new-onset LBBB were male sex (HR 0.8 [0.66-0.98], p = 0.028) history of atrial fibrillation (HR 1.29, 95% CI [1.01 - 1.64], p = 0.04), CABG (HR 1.27, [1.08 - 1.51], p = 0.004) and MI (HR 1.19, 95% CI [1.01 - 1.40], p = 0.034). In conclusion, in a contemporary registry of outpatients with CCS, the prevalence of LBBB was 4.4% and the additional 5-years incidence 6.2%. LBBB, in itself, was not associated with a higher risk of major adverse cardiovascular events or all cause mortality. It was however an independent predictor of risk of hospitalization for heart failure and permanent pacemaker implantation.

Left ventricular end-systolic contractile entropy can predict cardiac prognosis in patients with complete left bundle branch block.

BACKGROUND: Several patients with complete left bundle branch block (CLBBB) show left ventricular (LV) dyssynchrony and poor cardiac prognosis. However, the prognostic value of LV end-systolic contractile entropy which was measured by single-photon emission computer tomography (SPECT) has not been elucidated in patients with CLBBB. METHODS AND RESULTS: We recruited consecutive 115 sinus-rhythm patients with CLBBB who underwent ECG-gated 201TlCl-SPECT. After 30 days of observation, finally 102 patients (75.2 ± 9.5 years, 62 male) were enrolled and observed retrospectively for a median of 671 days. Twenty-five patients fell into major cardiac events. Multivariate Cox regression analysis showed estimated glomerular filtration rate (eGFR) ≤ 39.35 mL/min and entropy ≥ 79% were significant and independent predictors for major cardiac events (hazard ratio: 4.256 and 7.587, P value = 0.006 and < 0.001, respectively). Machine learning (Random Forest method) revealed eGFR and entropy had higher feature importance than other predictors (0.140 and 0.138, respectively). Kaplan-Meyer curve analysis demonstrated that the group with entropy ≥ 79% and eGFR ≤ 39.36 mL/min had the worst cardiac prognosis (Logrank: P = 0.002). CONCLUSIONS: Left ventricular end-systolic contractile entropy predicts poor cardiac prognosis in patients with CLBBB, which may be more valuable than the other parameters of SPECT.

Long-term outcome of intraventricular conduction delays in the general population.

BACKGROUND: Previous population studies have presented conflicting results regarding the prognostic impact of intraventricular conduction delays (IVCD). METHODS: We studied long-term prognostic impact and the association with comorbidities of eight IVCDs in a random sample of 6,299 Finnish subjects (2,857 men and 3,442 women, mean age 52.8, SD 14.9 years) aged 30 or over who participated in the health examination including 12-lead ECG. For left bundle branch block (LBBB) and non-specific IVCD (NSIVCD), two different definitions were used. RESULTS: During 16.5 years' follow-up, 1,309 of the 6,299 subjects (20.8%) died and of these 655 (10.4%) were cardiovascular (CV) deaths. After controlling for known clinical risk factors, the hazard ratio for CV death, compared with individuals without IVCD, was 1.55 for the Minnesota definition of LBBB (95% confidence interval 1.04-2.31, p = .032) and 1.27 (95% confidence interval 0.80-2.02, p = .308) for the Strauss' definition of LBBB. Subjects with NSIVCD were associated with twofold to threefold increase in CV mortality depending on the definition. While right bundle branch block, left anterior fascicular block and incomplete bundle branch blocks were associated with seemingly higher mortality, this was no longer the case after adjustment for age and sex. The presence of R-R' pattern was not associated with any adverse outcome. CONCLUSIONS: In a population study with long-term follow-up, NSIVCD and Minnesota definition of LBBB were independently associated with CV mortality. Other IVCDs had no significant impact on prognosis. The prognostic impact of LBBB and NSIVCD was affected by the definition of the conduction disorder.

Right Bundle Branch Block: Current Considerations.

RBBB, a pattern seen on the 12-lead ECG, results when normal electrical activity in the His-Purkinje system is interrupted for some reason. The normal sequence of activation is altered in RBBB, with a resultant characteristic appearance on the ECG manifest by a widened QRS complex and changes in the directional vectors of the R and S waves. This ECG pattern is often seen in clinical practice and generally regarded as benign. The anatomy, epidemiology, causes, symptoms, ECG findings and diagnosis, differential diagnosis in ECG, treatment, complications, prognosis, with respect to RBBB are outlined here, demonstrating some typical ECGs of RBBB.

Fascicular Blocks: Update 2019.

Many advances in the knowledge of medical science are due to the observation of an unknown phenomenon that remains an open question. A plausible hypothesis must be demonstrated and proved through a scientific method in order to be accepted by the scientific community and the same results must be reached by following either the same or different techniques. The original case described by Rosenbaum MB et al., in this review triggered a series of anatomic and physiologic investigations with clinical and experimental observations that supported the trifascicular nature of the intraventricular conduction system of the heart and the concept of hemiblocks. The recognition and description of the left fascicular blocks made by the Argentinian School of Electrocardiology bridged an important gap in electrocardiography and many electrocardiograms that could not be explained until that moment could finally be understood. This review intends to redefine reliable criteria for the electrocardiographic and vectorcardiographic diagnosis of left fascicular blocks [hemiblocks]. The anatomy of the left bundle branch is also discussed to better understand the incidence, prevalence, clinical significance and main causes of left anterior and left posterior hemiblock either isolated or associated with right bundle branch block. This review offers the reader a reappraisal of the trifascicular nature of the intraventricular conduction system regarding the anatomy of the left bundle branch system and its pathophysiological and clinical significance.

Effect of a restrictive pacemaker implantation strategy on mortality after transcatheter aortic valve implantation.

OBJECTIVES: We sought to assess the safety of a restrictive permanent pacemaker implantation (PPI) strategy after transcatheter aortic valve implantation (TAVI) as compared to a liberal strategy. BACKGROUND: Conduction disturbances resulting in PPI are common after TAVI. However, conduction disturbances may be transient and PPI may be superfluous in some patients. METHODS: Until August 2015, we performed PPI in all patients with new complete left bundle branch block (LBBB, QRS > 120 milliseconds) or higher degree atrioventricular (AV) blocks (liberal strategy). From September 2015 onwards, LBBB established an indication for PPI only in the presence of new-onset AV block (PQ > 200 milliseconds) (restrictive strategy). We analyzed the impact of the restrictive strategy on pacemaker implantation rate, duration of hospital stay, and 1-year mortality. RESULTS: Between January 2014 and December 2016, 383 consecutive, pacemaker-naive patients underwent TAVI with the liberal PPI strategy and subsequently 384 with the restrictive strategy. The restrictive strategy significantly reduced the percentage of patients undergoing PPI before discharge (17.2% vs. 38.1%, p < .001) and length of hospital stay (intensive care unit 52 ± 55 vs. 60 ± 52 hours, p < .001; general ward 10.6 ± 5.7 vs. 11.5 ± 5.7 days, p = .001). One-year all-cause mortality was not significantly different between groups (14.1% vs. 11.7%, log-rank p = .28). However, sudden death was more frequent in the restrictive group (3.4% vs. 1.3%, log-rank p = .049). CONCLUSIONS: As compared to a liberal indication for PPI, a restrictive indication reduced PPI rate and length of hospital stay without significantly affecting all-cause mortality. The observed increase in the risk of sudden death with the restrictive PPI indication deserves further investigation.

Mortality in Patients With Right Bundle-Branch Block in the Absence of Cardiovascular Disease.

Background Right bundle-branch block (RBBB) occurs in 0.2% to 1.3% of people and is considered a benign finding. However, some studies have suggested increased risk of cardiovascular morbidity and mortality. We sought to evaluate risk attributable to incidental RBBB in patients without prior diagnosis of cardiovascular disease (CVD). Methods and Results We reviewed the Mayo Clinic Integrated Stress Center database for exercise stress tests performed from 1993 to 2010. Patients with no known CVD-defined as absence of coronary disease, structural heart disease, heart failure, or cerebrovascular disease-were selected. Only Minnesota residents were included, all of whom had full mortality and outcomes data. There were 22 806 patients without CVD identified; 220 of whom (0.96%) had RBBB, followed for 6 to 23 years (mean 12.4±5.1). There were 8256 women (36.2%), mean age was 52±11 years; and 1837 deaths (8.05%), including 645 cardiovascular-related deaths (2.83%), occurred over follow-up. RBBB was predictive of all-cause (hazard ratio [HR], 1.5; 95% CI, 1.1-2.0; P=0.0058) and cardiovascular-related mortality (HR,1.7; 95% CI, 1.1-2.8; P=0.0178) after adjusting for age, sex, diabetes mellitus, hypertension, obesity, current and past history of smoking, and use of a heart rate-lowering drug. Patients with RBBB exhibited more hypertension (34.1% versus 23.7%, P<0.0003), decreased functional aerobic capacity (82±25% versus 90±24%; P<0.0001), slower heart rate recovery (13.5±11.5 versus 17.1±9.4 bpm; P<0.0001), and more dyspnea (28.2% versus 22.4%; P<0.0399) on exercise testing. Conclusions Patients with RBBB without CVD have increased risk of all-cause mortality, cardiovascular-related mortality, and lower exercise tolerance. These data suggest RBBB may be a marker of early CVD and merit further prospective evaluation.

Prevalence and incidence of intra-ventricular conduction delays and outcomes in patients with heart failure and reduced ejection fraction: insights from PARADIGM-HF and ATMOSPHERE.

AIMS: The importance of intra-ventricular conduction delay (IVCD), the incidence of new IVCD and its relationship to outcomes in heart failure and reduced ejection fraction (HFrEF) are not well studied. We addressed these questions in the PARADIGM-HF and ATMOSPHERE trials. METHODS AND RESULTS: The risk of the primary composite outcome of cardiovascular death or heart failure hospitalization and all-cause mortality were estimated by use of Cox regression according to baseline QRS duration and morphology in 11 861 patients without an intracardiac device. At baseline, 1789 (15.1%) patients had left bundle branch block (LBBB), 524 (4.4%) right bundle branch block (RBBB), 454 (3.8%) non-specific IVCD, 2588 (21.8%) 'mildly abnormal' QRS (110-129 ms) and 6506 (54.9%) QRS <110 ms. During a median follow-up of 2.5 years, the risk of the primary composite endpoint was higher among those with a wide QRS, irrespective of morphology: hazard ratios (95% confidence interval) LBBB 1.36 (1.23-1.50), RBBB 1.54 (1.31-1.79), non-specific IVCD 1.65 (1.40-1.94) and QRS 110-129 ms 1.35 (1.23-1.47), compared with QRS duration <110 ms. A total of 1234 (15.6%) patients developed new-onset QRS widening ≥130 ms (6.1 per 100 patient-years). Incident LBBB occurred in 495 (6.3%) patients (2.4 per 100 patient-years) and was associated with a higher risk of the primary composite outcome [hazard ratio 1.42 (1.12-1.82)]. CONCLUSION: In patients with HFrEF, a wide QRS was associated with worse clinical outcomes irrespective of morphology. The annual incidence of new-onset LBBB was around 2.5%, and associated with a higher risk of adverse outcomes, highlighting the importance of repeat electrocardiogram review. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT0083658 (ATMOSPHERE) and NCT01035255 (PARADIGM-HF).

Electrocardiographic Predictors of Mortality in Acute Anterior Wall Myocardial Infarction With Right Bundle Branch Block and Right Precordial Q-Waves (qRBBB).

BACKGROUND: Published data on the clinical, electrocardiographic, and angiographic profile of acute anterior-wall ST-elevation myocardial infarction (STEMI) with right bundle branch block with q in leads V1, V2 (qRBBB) are scarce. The aim of this study was to estimate the incidence of short-term mortality and in-hospital complications in acute qRBBB STEMI and identify the electrocardiographic (ECG) predictors of a poor outcome. METHODS: We conducted a single-centre retrospective study among the patients with acute anterior-wall STEMI and qRBBB pattern on ECG. All relevant clinical and treatment data were collected from the electronic medical records. All the ECGs taken during the index hospitalization were subjected to detailed analysis. RESULTS: Among the 272 qRBBB patients included in the study, 64% had thrombolysis in myocardial infarction (TIMI) risk score of ≥6, and 41% were in Killip class III or IV at the time of presentation. The in-hospital mortality rate was 42.6%. There was a high incidence of ventricular tachyarrhythmias (12%), complete heart block (13%), heart failure (69%), and cardiogenic shock (52%). Extreme deviation of mean QRS axis to the right (180 to 269 degrees) in the baseline ECG was associated with high in-hospital mortality (odds ratio: 13.43; 95% confidence interval: 1.48-122.03; P = 0.021). CONCLUSIONS: Acute qRBBB myocardial infarction is a sinister form of acute coronary syndrome that entails high in-hospital mortality and morbidity, necessitating early recognition and prompt institution of reperfusion therapy. Extreme deviation of QRS axis to the right (180 to 269 degrees) is a significant electrocardiographic predictor of in-hospital mortality.