Clinical Characteristics, Management, and Outcomes of Acute Coronary Syndrome in Patients With Right Bundle Branch Block on Presentation

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.

New permanent bundle-branch block and long-term prognosis of patients with new onset ST-elevation myocardial infarction who underwent percutaneous coronary intervention

Aim: The aim of the study was to evaluate the potential predictive value of permanent RBBB and LBBB for longer-term prognosis in patients with new-onset STEMI who underwent percutaneous coronary intervention (PCI).

Methods: Patients with new-onset STEMI that underwent emergency PCI at our department from June 2012 to September 2020 were included in the study. Gensini score (GS) was employed to evaluate the severity of coronary lesions. The primary endpoint of the study was the occurrence of major adverse cardiac and cerebrovascular events (MACCEs), the composite of cardiac mortality, recurrence of myocardial infarction, cardiac shock, stroke, stent thrombosis, or revascularization. We also set all-cause mortality as a secondary endpoint.

Results: Out of the 547 patients, 29 patients had new-onset permanent LBBB, 51 patients had new-onset permanent RBBB, and 467 patients had no bundle-branch block (BBB). The occurrence of no BBB, new permanent LBBB, or RBBB was not associated with the severity of coronary artery lesions as evaluated by the GS. After follow-up at an average of 43.93 months, MACCEs occurred in 52 patients. Kaplan-Meier analysis showed that patients with new-onset RBBB were at greater risk for MACCEs compared to those with new onset LBBB (χ² = 5.107, p = 0.021). Also, an independent correlation was found between new permanent RBBB and LBBB and MACCEs risk. The adjusted hazard ratios (HRs) were 6.862 [95% confidence interval (CI) of 3.764–12.510] for the new-onset permanent RBBB and 3.395 (95% CI of 1.280–9.005) for LBBB, compared to those with no BBB, respectively (both p < 0.05).

Conclusion: New onset permanent RBBB in patients with new onset STEMI who underwent PCI may be correlated independently with increased risk of poor long-term prognosis.

Frequency and Significance of Right Bundle Branch Block and Subclinical Coronary Atherosclerosis in Asymptomatic Individuals

Limited data exist regarding the association between right bundle branch block (RBBB) and subclinical coronary atherosclerosis. This study investigated the influence of RBBB on subclinical coronary atherosclerosis detected by coronary computed tomographic angiography (CCTA) in an asymptomatic population. We retrospectively analyzed 7,205 asymptomatic individuals (mean age 54.4 ± 7.9 years and 4,695 men [65.2%]) with no prior history of coronary artery disease who voluntarily underwent CCTA and 12-lead electrocardiographic evaluation as part of a general health examination. The degree and extent of subclinical coronary atherosclerosis were evaluated by CCTA, and ≥50% diameter stenosis was defined as significant. The association between RBBB and subclinical coronary atherosclerosis was determined by logistic regression and propensity score matching analyses. Of study participants, 116 (1.6%) had RBBB. After adjustment for cardiovascular risk factors, there were no statistically significant differences in the adjusted odds ratios of RBBB for any atherosclerotic plaque (0.87, 95% confidence interval [CI] 0.57 to 1.32), calcified plaque (0.78, 95% CI 0.51 to 1.19), noncalcified plaque (1.44, 95% CI 0.77 to 2.69), mixed plaque (1.12, 95% CI 0.52 to 2.39), and significant coronary artery stenosis (0.92, 95% CI 0.48 to 1.74). Similarly, in the 5: 1 propensity score-matched population (n = 696), there were no statistically significant differences in the odds ratios for any subclinical coronary atherosclerosis between participants with and without RBBB (p for all >0.05). In conclusion, through this large cross-sectional study of asymptomatic individuals who underwent CCTA and electrocardiography evaluation, individuals with RBBB were not associated with an increased risk of subclinical coronary atherosclerosis compared with those without RBBB.

Clinical characteristics and the severity of coronary atherosclerosis of different subtypes of bundle-branch block

BACKGROUND

Right bundle-branch block (RBBB) and left bundle-branch block (LBBB) play a role in the pathogenesis and progression of coronary artery disease (CAD). However, the clinical features and the severity of coronary artery disease associated with different subtypes of bundle-branch block, according to time of new appearance, is not well characterized in patients with no known CAD.

METHODS

We retrospectively analyzed data pertaining to consecutive patients with RBBB or LBBB who underwent coronary angiography. The severity of coronary lesions was evaluated using the SYNTAX score. The differential effect of new-onset RBBB, old RBBB, new-onset LBBB, and old LBBB on the severity of CAD and its association with clinical characteristics was quantified. Multivariate logistic regression analysis was performed to evaluate the effect of RBBB and LBBB on the degree of coronary atherosclerosis in patients without known CAD.

RESULTS

Out of the 243 patients, 72 patients had old LBBB, 37 had new-onset LBBB, 93 patients had old RBBB, and 41 patients had new-onset RBBB. On univariate analysis, age, systolic blood pressure, diastolic blood pressure, creatinine, serum glucose, and glycosylated hemoglobin level were associated with high SYNTAX score (p < .05 for all). Patients in the new-onset RBBB, old RBBB, new-onset LBBB, and old LBBB groups showed significant differences in baseline characteristics and coronary atherosclerosis (p < .05 for all). However, there were no significant between-group differences with respect to the degree of coronary atherosclerosis as assessed by SYNTAX score.

CONCLUSIONS

New-onset RBBB, old RBBB, new-onset LBBB, and old LBBB were not associated with the severity of coronary lesions as assessed by SYNTAX score in patients without known CAD.

Left bundle branch pacing for cardiac resynchronization therapy: A systematic literature review and meta-analysis

BACKGROUND

Left bundle branch pacing (LBBP) recently has been suggested as an alternative modality to deliver cardiac resynchronization therapy (CRT). Data on LBBP for CRT are limited to small sample reports, and clinical benefits and risks have not been systematically assessed. We sought to systematically examine published studies of LBBP for CRT and quantify the feasibility and efficacy of the therapy.

METHODS

Cochrane Library, PubMed, Web of Science, and Embase databases were searched from inception to September 30, 2020 to identify relevant studies evaluating LBBP in patients for CRT. Clinical outcomes of interest included implant success rate, QRS duration (QRSd), pacing threshold, left ventricular (LV) function at baseline and follow-up, heart failure-related hospitalization, and mortality. Data were extracted and summarized.

RESULTS

A total of six studies (two single-arm studies and four comparative studies) involving 174 patients were included. The results showed that the average age of patients was 64.9 years and all were implanted for CRT. The procedural success rate was only reported in two studies (97% and 81.1%, respectively). LBBP resulted in a narrow of mean QRSd from 172.7 ± 4.8 to 115.1 ± 7.6 ms. LV function, including LV ejection fraction and LV end-diastolic dimension improved at follow-up. During a mean follow-up of 8.1 months, 1.3% of patients experienced heart failure-related hospitalization and no patients died.

CONCLUSION

LBBP is a feasible strategy with significant efficacy and safety for CRT candidates.

In Hospital Outcomes of Patients With Right Bundle Branch Block and Anterior Wall ST-Segment Elevation Myocardial Infarction (From a Nationwide Study Using the National Inpatient Sample)

Previous studies have reported worse outcomes for patients with right bundle branch block (RBBB) complicating acute ST-segment elevation myocardial infarction (STEMI). There is a paucity of data examining outcomes with RBBB and STEMI in contemporary large-scale studies. This study aims to explore the outcomes of patients with anterior wall STEMI (AW-STEMI) and RBBB. Using ICD-9 codes, we queried the National Inpatient Sample of 1999 to 2014 to identify AW-STEMI admissions and stratified them for the presence of RBBB. Primary outcome was in-hospital mortality within 30 days. Secondary outcomes included acute heart failure, complete heart block, and permanent pacemaker implantation. Cox-proportional logistic regression models were used to determine the hazard ratios of the primary outcome and secondary outcomes and interventions. Among 1,075,875 weighted anterior wall STEMI (AW-STEMI) admissions, 19,153 (1.8%) had RBBB. Compared with patients without RBBB, mortality was significantly higher for patients with RBBB (9.2% vs 15.3%; p <0.0001). RBBB in the setting of AW-STEMI was associated with a 66% increased risk of 30-day in-hospital mortality (hazard ratios [HR], 1.66; 95% confidence interval [CI], 1.52 to1.81; p <0.0001) and a higher likelihood of acute heart failure (HR, 1.37; 95% CI, 1.29 to 1.45; p <0.0001), complete heart block (HR, 2.90; 95% CI, 2.64 to 3.18; p <0.0001) and utilization of a permanent pacemaker (HR, 2.51; 95% CI, 1.89 to 3.35; p <0.0001). In conclusion, the presence of RBBB in the setting of an AW-STEMI is a significant independent predictor of a poor prognosis, including a higher rate of acute heart failure, complete heart block, need for a permanent pacemaker, and a higher 30-day in-hospital mortality.

Differences in presentation and clinical outcomes between left or right bundle branch block and ST segment elevation in patients with acute myocardial infarction

Background:

In patients with acute myocardial infarction, the presence of a left bundle branch block or right bundle branch block may be associated with worse prognosis compared to isolated ST segment elevation. However, specificities in clinical presentation and outcomes of acute myocardial infarction patients with left bundle branch block or right bundle branch block are poorly characterized.

Methods:

We analysed acute myocardial infarction patients with left bundle branch block (n=880), right bundle branch block (n=732) or ST segment elevation without bundle branch block (n=15,852) included in the Acute Myocardial Infarction in Switzerland-Plus registry between 2008–2019.

Results:

Acute myocardial infarction patients with bundle branch block were older and had more pre-existing cardiovascular conditions compared to ST segment elevation. Pulmonary oedema and cardiogenic shock were most frequent in patients with left bundle branch block (18.8% vs 12.0% for right bundle branch block and 7.9% for ST segment elevation, p&lt;0.001). Acute myocardial infarction patients with bundle branch block had more three-vessel (40.6% vs 25.3%, p&lt;0.001 vs ST segment elevation) and left main disease (5.6% vs 2.0%, p&lt;0.001 vs ST segment elevation). Major adverse cardiac and cerebrovascular events, a composite of reinfarction, stroke/transient ischaemic attack, and death during hospitalization, were highest in acute myocardial infarction patients with left bundle branch block (13.9% vs 9.9% for right bundle branch block and 6.7% for ST segment elevation, p&lt;0.05), which was driven by hospital mortality. After multivariate adjustment, however, mortality was similar in patients with left bundle branch block and lower in patients with right bundle branch block, respectively, when compared to ST segment elevation. Mortality was only increased when a right bundle branch block with concomitant STE was present (odds ratio 1.77, 95% confidence interval 1.19–2.64, p&lt;0.01 vs ST segment elevation).

Conclusions:

Compared to ST segment elevation, an isolated bundle branch block reflects high-risk clinical characteristics but does not independently determine increased hospital mortality in acute myocardial infarction.

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.

Long-term outcome of pre-specified ECG patterns in acute coronary syndrome

BACKGROUND

Long-term outcome of real-life acute coronary syndrome (ACS) patients with selected ECG patterns is not well known.

PURPOSE

To survey the 10-year outcome of pre-specified ECG patterns in ACS patients admitted to a university hospital.

METHODS

A total of 1184 consecutive acute coronary syndrome patients in 2002-2003 were included and followed up for 10 years. The patients were classified into nine pre-specified ECG categories: 1) ST elevation; 2) pathological Q waves without ST elevation; 3) left bundle branch block (LBBB); 4) right bundle branch block (RBBB) 5) left ventricular hypertrophy (LVH) without ST elevation except in leads aVR and/or V₁; 6) global ischemia ECG (ST depression ≥0.5 mm in 6 leads, maximally in leads V_4-5 with inverted T waves and ST elevation ≥0.5 mm in lead aVR); 7) other ST depression and/or T wave inversion; 8) other findings and 9) normal ECG.

RESULTS

Any abnormality in the ECG, especially Q waves, LBBB, LVH and global ischemia, had negative effect on outcome. In age- and gender adjusted Cox regression analysis, pathological Q waves (HR 2.28, 95%CI 1.20-4.32, p = .012), LBBB (HR 3.25, 95%CI 1.65-6.40, p = .001), LVH (HR 2.53, 95%CI 1.29-4.97, p = .007), global ischemia (HR 2.22, 95%CI 1.14-4.31, p = .019) and the combined group of other findings (HR 3.01, 95%CI 1.56-6.09, p = .001) were independently associated with worse outcome.

CONCLUSIONS

During long-term follow-up of ACS patients, LBBB, ECG-LVH, global ischemia, and Q waves were associated with worse outcome than a normal ECG, RBBB, ST elevation or ST depression with or without associated T-wave inversion. LBBB was associated with the highest mortality rates.

Perinatal inflammation and childhood adiposity - a gender effect?

Background: To determine the association of maternal and fetal inflammatory factors with gender-specific infant adiposity, independent of leptin.Methods: Analysis of anthropometry from 265 mother-infant pairs at birth and 280 pairs at 6 months from the randomised control trial of low glycaemic index diet in pregnancy (ROLO) study (Randomised control trial of low glycaemic index diet) and their association with Maternal TNF-alpha, interleukin 6 and leptin as measured in early and late pregnancy and fetal levels in cord blood.Results: No associations were noted in the male cohort. On multiple regression amongst the female neonatal cohort late pregnancy IL-6 was inversely associated with sum of skinfolds (p ≤ .001); at 6 months infant sum of skinfolds were positively associated with early pregnancy IL-6 (p = .046) and central adiposity positively associated with early pregnancy TNF alpha (p = .018) independent of leptin.Conclusion: Although maternal inflammatory cytokines were not associated with neonatal adiposity independent of leptin (as this association is known), both IL-6 and TNF-α were associated with female infant anthropometry at 6 months of age independent of leptin. These results suggest inflammatory cytokines may exert an in-utero influence on later infant adiposity with a tendency to influence female adiposity more than male. Further research is required to ascertain whether these cytokines may be used as reliable early predictors of infant adiposity.

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

We sought to characterize presenting electrocardiographic findings in patients with acute coronary syndromes (ACSs) and out-of-hospital cardiac arrest (OHCA). In the Global Registry of Acute Coronary Events and Canadian ACS Registry I, we examined presenting and 24- to 48-hour follow-up ECGs (electrocardiogram) of ACS patients who survived to hospital admission, stratified by presentation with OHCA. We assessed the prevalence of ST-segment deviation and bundle branch blocks (assessed by an independent ECG core laboratory) and their association with in-hospital and 6-month mortality among those with OHCA. Of the 12,040 ACS patients, 215 (1.8%) survived to hospital admission after OHCA. Those with OHCA had higher presenting rates of ST-segment elevation, ST-segment depression, T-wave inversion, precordial Q-waves, left bundle branch block (LBBB), and right bundle branch block (RBBB) than those without. Among patients with OHCA, those with ST-segment elevation had significantly lower in-hospital mortality (20.9% vs 33.0%, p = 0.044) and a trend toward lower 6-month mortality (27% vs 39%, p = 0.060) compared with those without ST-segment elevation. Conversely, among OCHA patients, LBBB was associated with significantly higher in-hospital and 6-month mortality rates (58% vs 22%, p <0.001, and 65% vs 28%, p <0.001, respectively). ST-segment depression and RBBB were not associated with either outcome. Sixty-three percent of bundle branch blocks (RBBB or LBBB) on the presenting ECG resolved by 24 to 48 hours. In conclusion, compared with ACS patients without cardiac arrest, those with OHCA had higher rates of ST-segment elevation, LBBB, and RBBB on admission. Among OHCA patients, ST-segment elevation was associated with lower in-hospital mortality, whereas LBBB was associated with higher in-hospital and 6-month mortality.