Association of right bundle branch block or intraventricular conduction delay with recurrence of atrial fibrillation after catheter ablation

BACKGROUND

The association between bundle branch block (BBB) and recurrence of atrial fibrillation (AF) after catheter ablation is unclear. The aim of this study was to determine whether AF combined with BBB is associated with AF recurrence after catheter ablation.

METHODS

A total of 477 consecutive AF patients who underwent catheter ablation were included. The AF patients were divided into three groups according to BBB: AF without BBB (n = 427), AF with right bundle branch block (AF with RBBB) (n = 16), and AF with intraventricular conduction delay (AF with IVCD) (n = 34).

RESULTS

Of the 477 AF patients (mean age 57 years, 81% men, median CHA2 DS2 -VASc score of 1), 16 (3.4%) patients had RBBB, and 34 (7.1%) patients had IVCD. During a mean follow-up of 15.2 ± 6.7 months, 119 patients (24.9%) had recurrence of AF. Of these, 111 (26%) patients were in the AF without BBB group, with 2 (12.5%) and 6 (17.6%) patients in the RBBB and IVCD groups, respectively. The Kaplan-Meier estimate of the rate of recurrent AF was not significantly different among the three groups (p = .39). Multivariable analysis showed that persistent AF (HR 1.7, 95% CI 1.15-2.50, p = .007), chronic kidney disease (HR 2.94, 95% CI 1.20-7.17, p = .01), and left atrial diameter (HR 1.04, 95% CI 1.009-1.082, p = .01) were significantly associated with AF recurrence.

CONCLUSION

AF with BBB was not significantly associated with the recurrence of AF after catheter ablation in middle-aged patients with low-risk cardiovascular profile.

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.

Admission ECG changes predict short term-mortality after acute myocardial infarction less reliable in patients with diabetes

Prior studies examined association between short-term mortality and certain changes in the admission ECG in acute myocardial infarction (AMI). Nevertheless, little is known about possible differences between patients with diabetes and without diabetes in this regard. So the aim of the study was to investigate the association between 28-day case fatality according to certain ECG changes comparing AMI cases with and without diabetes from the general population. From 2000 until 2017 a total of 9756 AMI cases was prospectively recorded in the study Area of Augsburg, Germany. Each case was assigned to one of the following groups according to admission ECG: ‘ST-elevation’, ‘ST-depression’, ‘only T-negativity’, ‘predominantly bundle branch block’, ‘unspecific changes’ and ‘normal ECG’ (the last two were put together for regression analyses). Multivariable adjusted logistic regression models were calculated to compare 28-day case-fatality between the ECG groups for the total sample and separately for diabetes and non-diabetes cases. For the non-diabetes group, the parsimonious logistic regression model revealed significantly better 28-day-outcome for the ‘normal ECG / unspecific changes’ group (OR: 0.47 [0.29–0.76]) compared to the reference group (STEMI). Contrary, in AMI cases with diabetes the category ‘normal ECG / unspecific changes’ was not significantly associated with lower short-term mortality (OR: 0.87 [0.49–1.54]). Neither of the other ECG groups was significantly associated with 28-day-mortality in the parsimonious logistic regression models. Consequently, the absence of AMI-typical changes in the admission ECG predicts favorable short-term mortality only in non-diabetic cases, but not so in patients with diabetes.

[High-risk ECGs in acute chest pain : Signs of acute ischemia beyond STEMI]

BACKGROUND

Obtaining an electrocardiogram (ECG) is the gold standard for initial diagnostics of atraumatic chest pain. To provide optimal patient care, the treating physician has to be proficient in recognizing early signs of myocardial ischemia. Information from the clinical assessment and typical ECG signs have to be recognized promptly in order to diagnose myocardial ischemia early.

METHODS

A selective literature search in international databases (PubMed, Cochrane Library, Google Scholar) was conducted; current, topic-specific websites and literature were also included and evaluated.

RESULTS

Several subtle ECG abnormalities exist besides the typical ST-elevation myocardial infarction (STEMI) and well-known STEMI equivalents and may point to possible myocardial ischemia.

DISCUSSION

To fully evaluate the ECG in patients with atraumatic chest pain, typical signs of ischemia like STEMI as well as subtle ECG signs should be recognized to allow early cardiac intervention.

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.

Right bundle brunch block in patients with acute myocardial infarction is associated with a higher in-hospital arrhythmic risk and mortality, and a worse prognosis after discharge

INTRODUCTION

Recently, the presence of right bundle brunch block (RBBB) in patients with persistent ischaemic symptoms has been suggested as an indication for emergent coronary angiography.

OBJECTIVE

The aim of this study was to assess the prognostic impact of RBBB in patients with acute myocardial infarction (AMI) before the implementation of the recent recommendations.

METHODS

We retrospectively studied consecutive patients admitted with AMI between 2011 and 2013. Patients with left bundle brunch block, pacemaker, or nonspecific intraventricular conduction delay were excluded. Patients with RBBB were compared with those without RBBB. Clinical characteristics, in-hospital evolution, and major adverse cardiovascular events (MACE) during follow-up, defined as cardiovascular death, sustained ventricular arrhythmias, acute heart failure syndromes, recurrent myocardial infarction, or acute stroke, were analysed.

RESULTS

The analysis included 481 patients. Thirty two patients (6.7%) had RBBB. Patients with RBBB were older. During hospital admission, RBBB patients had a higher rate of sustained ventricular tachycardia and death. Survival curve analysis showed that patients with RBBB had a lower in-hospital survival rate (Log-rank, p = 0.004). After discharge, during a mean follow-up time of 24.3 ± 11.6 months, 53 patients (12%) died. Survival curve analysis showed a lower survival rate free of MACE for those patients with RBBB (Log-rank, p = 0.011). RBBB was independently associated with MACE occurrence (HR 2.17, 95% CI 1.07-4.43; p = 0.033), after adjusting for demographic data, coronary angiography findings, treatment performed, echocardiographic evaluation, and medical therapy.

CONCLUSION

Patients with RBBB had a higher rate of in-hospital mortality and arrhythmic events, and an increased risk of MACE during follow-up.

Clinical Presentations and Outcomes in Patients Presenting With Acute Cardiac Events and Right Bundle Branch Block

We conducted a retrospective analysis of 50 974 patients admitted with acute cardiac events with and without right bundle branch block (RBBB) over 23 years. Compared to non-RBBB, patients with RBBB (n = 386; 0.8%) were 3 years older ( P = .001), more likely to present with breathlessness rather than chest pain ( P = .001), and had more diabetes mellitus ( P = .001). Patients with RBBB had significantly higher cardiac enzymes ( P = .001); however, there were no significant differences in the presentation with ST-segment elevation myocardial infarction (24.6% vs 22.2%), non-ST-segment elevation myocardial infarction (23.7% vs 22.4%), and unstable angina (51.7% vs 55.4%). Patients with RBBB were more likely to have congestive heart failure (CHF; 9.6% vs 3.2%, P = .001), cardiogenic shock (10.6% vs 1.7%, P = .001), and ventricular tachyarrhythmias (7.3% vs 2.2%, P = .001). Left ventricular ejection fraction and hospital length of stay were comparable between the groups. All-cause mortality was 5 times greater in patients with RBBB (21% vs 4.2%, P = .001). Right bundle branch block was independent predictor of mortality (adjusted odd ratio 5.14; 95% confidence interval: 3.90-6.70). Subanalysis comparing normal QRS, RBBB, and left BBB showed that RBBB was associated with the worst outcomes except for CHF. Although RBBB presents in only about 1% of patients with cardiac disease, it was found to be an independent predictor of hospital mortality.

Right bundle branch block: Prevalence, incidence, and cardiovascular morbidity and mortality in the general population

Background: Right bundle branch block (RBBB) is among the most common electrocardiographic abnormalities. Objectives: To establish the prevalence and incidence of RBBB in the general population without cardiovascular events (CVE) and whether RBBB increases cardiovascular morbidity and mortality compared with patients with a normal electrocardiogram (ECG). Methods: A historical study of two cohorts including 2981 patients from 29 primary health centres without baseline CVE. Cox (for CVE) and logistic (for cardiovascular factors) regression was used to assess their association with RBBB. Results: Of the patients (58% women; mean age 65.9), 92.2% had a normal ECG, 4.6% incomplete RBBB (iRBBB) and 3.2% complete RBBB (cRBBB). Mean follow-up was five years. Factors associated with appearance of cRBBB were male sex (HR = 3.8; 95%CI: 2.4-6.1) and age (HR = 1.05 per year; 95%CI: 1.03-1.08). In a univariate analysis, cRBBB was associated with an increase in all-cause mortality but only bifascicular block (BFB) was significant after adjusting for confounders. cRBBB tended to increase CVE but the results were not statistically significant. Presence of iRBBB was not associated with adverse outcomes. Patients with iRBBB who progressed to cRBBB showed a higher incidence of heart failure and chronic kidney disease. Conclusion: In this general population cohort with no CV disease, 8% had RBBB, with a higher prevalence among men and elderly patients. Although all-cause mortality and CVE tended to increase in the presence of cRBBB, only BFB showed a statistically significant association with cRBBB. Patients with iRBBB who progressed to cRBBB had a higher incidence of CVE. We detected no effect of iRBBB on morbidity and mortality.

Diagnosis of right bundle branch block: a concordance study

BACKGROUND

Right bundle branch block is one of the most common electrocardiographic abnormalities. Most cases of right bundle branch block are detected in asymptomatic patients in primary care, so a correct interpretation of electrocardiograms (ECGs) at this level is necessary. The objective of this research is to determine the degree of concordance in the diagnosis of incomplete and complete right bundle branch block between four primary care researchers and a cardiologist.

METHODS

The research design is a retrospective cohort study of patients over 18 years of ages of patients over 18 years of ages who underwent an ECG for any reason and were diagnosed with right bundle branch block by their physician. The physicians participating, 4 primary care researchers and a cardiologist were specialized in interpreting electrocardiographic records. The diagnosis of incomplete and complete right bundle branch block was recorded and other secondary variables were analysed. In case of diagnostic discordance between the researchers, the ECGs were reviewed by an expert cardiologist, who interpreted them, established the diagnosis and analysed the possible causes for the discrepancy.

RESULTS

We studied 160 patients diagnosed with right bundle branch block by their general practise. The patients had a mean age of 64.8 years and 54% of them were men. The concordance in the diagnosis of incomplete right bundle branch block showed a Fleiss' kappa index (k) of 0.71 among the five researchers and of 0.85 among only the primary care researchers. The k for complete right bundle branch block was 0.93 among the five researchers and 0.96 among only the primary care researchers.

CONCLUSION

The interobserver agreement in the diagnosis of right bundle branch block performed by physicians specialized in ECG interpretation (primary care physicians and a cardiologist) was very good. The variability was greater for the diagnosis of incomplete right bundle branch block.

Prognostic impact of bundle branch block after acute coronary syndrome. Does it matter if it is left of right?

BACKGROUND

In previous guidelines, acute coronary syndromes (ACS) with new or presumably new left bundle branch block (LBBB) were an indication for reperfusion treatment, preferably with primary angioplasty. Recent guidelines also included the presence of right bundle branch block (RBBB) in this recommendation. It was our objective to evaluate in a population of patients with ACS the differential impact of RBBB and LBBB in prognosis.

METHODS

Consecutive patients included prospectively in a single-centre registry of ACS were included in the study. Patients were analyzed according to baseline ECG characteristics (normal QRS, LBBB or RBBB). Primary outcome was all-cause mortality at one-year follow-up. We used Cox-proportional hazards models to assess the predictive value for the primary outcome.

RESULTS

A total of 3990 patients were included in, with a mean age of 64 (13) years, 72% males, 3.4% with LBBB and 4.3% with RBBB. Patients with BBB were older, with more previous history of myocardial infarction and coronary revascularization and higher prevalence of cardiovascular risk factors (except smoking). Medical treatment was similar but they were less often submitted to angioplasty. In univariate analysis, BBB patients had worst outcome (Log-rank, p < 0.001), but similar in LBBB and RBBB (Log-rank, p = 0.597). In multivariate analysis, only RBBB (HR 1.66, 95%CI 1.14-2.40, p = 0.007) is an independent predictor of all-cause mortality.

CONCLUSIONS

Patients with BBB have worst outcome after an ACS, particularly with RBBB. For that reason, we should pay special attention and treat these patients as aggressively as patients with normal QRS duration or LBBB.

Left ventricular ejection fraction and mortality in patients with ST-elevation myocardial infarction and bundle branch block

BACKGROUND

The aim of our study is to assess the effect of bundle branch block (BBB) on mortality and left ventricular ejection fraction (LVEF) in ST-elevation myocardial infarction (STEMI) patients treated in the current era of percutaneous reperfusion therapy.

PATIENTS AND METHODS

In this retrospective cohort study, a total of 1123 STEMI patients treated in the University Medical Center Groningen from January 2011 until May 2013 were included. The follow-up duration was 2-4 years. Transthoracic echocardiography was performed within 2 weeks after STEMI.

RESULTS

In total, 23 (2.0%) patients presented with left BBB and 49 (4.4%) patients presented with right BBB. Two-year mortality after STEMI was 25.0% (n=18) in patients with BBB and 9.2% (n=97, P<0.001) in patients without BBB. Patients with BBB had more frequently a severely reduced LVEF (<30%) [20.0% (n=6) compared with 4.2% (n=21), P=0.002] and less frequently a normal LVEF [16.7% (n=5) compared with 35.7% (n=179), P=0.046]. After multivariable analysis, BBB did not remain an independent predictor of mortality, but was an independent predictor of reduced LVEF.

CONCLUSION

The presence of a BBB was an independent predictor of a reduced LVEF. However, we found no effect of BBB on 2-year mortality in the current era of percutaneous reperfusion therapy.

Prognostic Significance of Right Bundle Branch Block for Patients with Acute Myocardial Infarction: A Systematic Review and Meta-Analysis

Background

The aim of the current meta-analysis was to assess the effect of right bundle branch block (RBBB) on mortality outcome in patients with acute myocardial infarction (AMI).

Material/Methods

Embase, PubMed, and Cochrane databases were searched through January 2015 using the keywords “RBBB”, “mortality”, “AMI”, “Coronary Heart Disease”, and “cardiovascular”. An odds ratio (OR) of RBBB on mortality endpoints was calculated using random-effects models.

Results

RBBB was associated with significantly increased overall mortality in patients with AMI. The OR of RBBB for deaths was 1.56 [95% confidence interval (CI), 1.44 to 1.68, p<0.001]. Moreover, RBBB showed a considerable effect on both in-hospital mortality (OR: 1.94, 95% CI: 1.60 to 2.37, p=0.002) and long-term mortality (OR: 1.49, 95% CI: 1.37 to 1.62, p<0.001).

Conclusions

RBBB is associated with an increased risk of all-cause mortality and indicates a poorer prognosis in patients with AMI.

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

We examined the relations between right bundle branch block (RBBB) and clinical characteristics, management, and outcomes among a broad spectrum of patients with acute coronary syndrome (ACS). Admission electrocardiograms of patients enrolled in the Global Registry of Acute Coronary Events (GRACE) electrocardiogram substudy and the Canadian ACS Registry I were analyzed independently at a blinded core laboratory. We performed multivariable logistic regression analysis to assess the independent prognostic significance of admission RBBB on in-hospital and 6-month mortality. Of 11,830 eligible patients with ACS (mean age 65; 66% non-ST-elevation ACS), 5% had RBBB. RBBB on admission was associated with older age, male sex, more cardiovascular risk factors, worse Killip class, and higher GRACE risk score (all p <0.01). Patients with RBBB less frequently received in-hospital cardiac catheterization, coronary revascularization, or reperfusion therapy (all p <0.05). The RBBB group had higher unadjusted in-hospital (8.8% vs 3.8%, p <0.001) and 6-month mortality rates (15.1% vs 7.6%, p <0.001). After adjusting for established prognostic factors in the GRACE risk score, RBBB was a significant independent predictor of in-hospital death (odds ratio 1.45, 95% CI 1.02 to 2.07, p = 0.039), but not cumulative 6-month mortality (odds ratio 1.29, 95% CI 0.95 to 1.74, p = 0.098). There was no significant interaction between RBBB and the type of ACS for either in-hospital or 6-month mortality (both p >0.50). In conclusion, across a spectrum of ACS, RBBB was associated with preexisting cardiovascular disease, high-risk clinical features, fewer cardiac interventions, and worse unadjusted outcomes. After adjusting for components of the GRACE risk score, RBBB was a significant independent predictor of early mortality.

Ventricular conduction abnormalities as predictors of long-term survival in acute de novo and decompensated chronic heart failure

Aims

Data on the prognostic role of left and right bundle branch blocks (LBBB and RBBB), and nonspecific intraventricular conduction delay (IVCD; QRS ≥ 110 ms, no BBB) in acute heart failure (AHF) are controversial. Our aim was to investigate electrocardiographic predictors of long‐term survival in patients with de novo AHF and acutely decompensated chronic heart failure (ADCHF).

Methods and Results

We analysed the admission electrocardiogram of 982 patients from a multicenter European cohort of AHF with 3.9 years' mean follow‐up. Half (51.5%, n = 506) of the patients had de novo AHF. LBBB, and IVCD were more common in ADCHF than in de novo AHF: 17.2% vs. 8.7% (P < 0.001) and 20.6% vs. 13.2% (P = 0.001), respectively, and RBBB was almost equally common (6.9% and 8.1%; P = 0.5), respectively. Mortality during the follow‐up was higher in patients with RBBB (85.4%) and IVCD (73.7%) compared with patients with normal ventricular conduction (57.0%); P < 0.001 for both. The impact of RBBB on prognosis was prominent in de novo AHF (adjusted HR 1.93, 1.03–3.60; P = 0.04), and IVCD independently predicted death in ADCHF (adjusted HR 1.79, 1.28–2.52; P = 0.001). Both findings were pronounced in patients with reduced ejection fraction. LBBB showed no association with increased mortality in either of the subgroups. The main results were confirmed in a validation cohort of 1511 AHF patients with 5.9 years' mean follow‐up.

Conclusions

Conduction abnormalities predict long‐term survival differently in de novo AHF and ADCHF. RBBB predicts mortality in de novo AHF, and IVCD in ADCHF. LBBB has no additive predictive value in AHF requiring hospitalization.

Relation of New Permanent Right or Left Bundle Branch Block on Short- and Long-Term Mortality in Acute Myocardial Infarction Bundle Branch Block and Myocardial Infarction

The aim of this study was to investigate the prognosis associated with bundle branch block (BBB) depending on location, time of appearance, and duration in patients with myocardial infarction (MI). From January 1998 to January 2008, we recruited 5,570 patients with acute MI. Thirty-day and 7-year all-cause mortality, according to BBB location, time of appearance, and duration were analyzed by multivariable analyses. BBB was present in 964 patients (17.3%); right BBB (RBBB) 10.6% and left BBB (LBBB) 6.7%. Overall mortality rate at 30 days was 13.2% (n = 738) and 7 years was 6.34 deaths per 100 patient-year. Both RBBB and LBBB were more frequently previous, 42.9% and 58.8%. Compared with non-BBB, all BBB groups showed higher prevalence of co-morbidities, especially rates of diabetes (49.0% vs 34.3%, p <0.001) and more often heart failure during hospitalization (54.5% vs 26.6%, p <0.001). Compared with RBBB, patients with LBBB had a higher prevalence of co-morbidities and a higher mortality, especially the new BBB, 30 days: 52.5% versus 31.6% and 7 years (incident rate): 27.2 versus 13.3 per 100 patient-year. New transient BBB had lower heart failure on admission (42.6% vs 58.3%, p = 0.008) and 30-day mortality (20.3% vs 69.6%, p <0.001) compared with permanent in both locations. New permanent RBBB was independently associated with 30-day (hazard ratio [HR] 2.01, 95% confidence interval [CI] 1.45 to 2.79) and 7-year mortality (HR 3.12, 95% CI 2.38 to 4.09). New-permanent LBBB was independently associated with 30-day (HR 2.15, 95% CI 1.47 to 3.15) and 7-year mortality (HR 2.91, 95% CI 2.08 to 4.08). In conclusion, in patients with acute MI, the appearance of a new BBB was independently associated with a higher 30-day and 7-year all-cause mortality.

A wide QRS/T angle in bundle branch blocks is associated with increased risk for coronary heart disease and all-cause mortality in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Repolarization abnormality in bundle branch blocks (BBB) is traditionally ignored. This study evaluated the prognostic value of QRS/T angle for mortality in the presence and absence of BBB.

METHODS AND RESULTS

Total 15,408 participants (mean age 54 years, 55.2% women, 26.9% blacks, 2.8% with BBB) were from the Arteriosclerosis Risk in Communities Study. Sex stratified Cox regression models were used to compute hazard ratios (HRs) with 95% confidence intervals (CIs) for coronary heart disease (CHD) and all-cause mortality for wide spatial QRS/T angle with and without BBB including right BBB (RBBB), left BBB (LBBB) and indetermined-type ventricular conduction defect (IVCD) and RBBB combined with left anterior fascicular block. During a median 22-year follow-up, 4767 deaths occurred, 728 of them CHD deaths. Using the No-BBB with QRS/T angle below median value as gender-specific reference groups, the mortality risk increase was significant for both women and men with No-BBB and QRS/T angle above the median value. In the pooled ICVD/LBBB group, the risk for CHD death was increased 15.9-fold in women and 6.04 fold in men, and for all-cause deaths 3.01-fold in women and 1.84-fold in men. However, the mortality risk in isolated RBBB group was only significantly increased in women but not in men.

CONCLUSION

A wide spatial QRS/T angle in BBB is associated with increased risk for CHD and all-cause mortality over and above the predictive value for BBB alone. The risk for women is as high as or higher than that in men.

Usefulness of electrocardiographic QRS/T angles with versus without bundle branch blocks to predict heart failure (from the Atherosclerosis Risk in Communities Study)

Repolarization abnormalities in the setting of bundle branch blocks (BBB) are generally ignored. We used Cox regression models to determine hazard ratios (HRs) with 95% confidence intervals (CIs) for incident heart failure (HF) associated with wide spatial and frontal QRS/T angle (upper twenty-fifth percentile of each) in men and women with and without BBB. This analysis included 14,478 participants (54.6% women, 26.4% blacks, 377 [2.6%] with BBB) from the Atherosclerosis Risk in Communities Study who were free of HF at baseline. Using No-BBB with normal spatial QRS/T angle as the reference group, the risk for HF in multivariable adjusted models was increased 51% for No-BBB with wide spatial QRS/T angle (HR 1.51, 95% CI 1.37 to 1.66), 48% for BBB with normal spatial QRS/T angle (HR 1.48, 95% CI 1.17 to 1.88), and the risk for incident HF was increased more than threefold for BBB with wide spatial QRS/T angle (HR 3.37, 95% CI 2.47 to 4.60). The results were consistent across subgroups by gender. Similar results were observed for the frontal plane QRS/T angle. In the pooled BBB group excluding right BBB, a positive T wave in lead aVR and heart rate 70 bpm and higher were also potent predictors of incident HF similar to the QRS/T angles. In conclusion, both BBB and wide QRS/T angles are predictive of HF, and concomitant presence of both carries a much higher risk than for either predictor alone. These findings suggest that repolarization abnormalities in the setting of BBB should not be considered benign or an expected consequence of BBB.

Canadian Cardiovascular Society guidelines on the use of cardiac resynchronization therapy: evidence and patient selection

Recent landmark trials provided the impetus to update the recommendations for cardiac resynchronization therapy (CRT). This article provides guidance on the prescription of CRT within the confines of published data. A future article will explore the implementation of these guidelines. These guidelines are intended to serve as a framework for the prescription of CRT within the Canadian health care system and beyond. They were developed through a critical evaluation of the existing literature, and expert consensus. The panel unanimously adopted each recommendation. The 8 recommendations relate to ensuring the adequacy of medical therapy before the initiation of CRT, the use of symptom severity to select candidates for CRT, differing recommendations based on the presence or absence of sinus rhythm, the presence of left bundle branch block vs other conduction patterns, and QRS duration. The use of CRT in the setting of chronic right ventricular pacing, left ventricular lead placement, and the routine assessment of dyssynchrony to guide the prescription of CRT are also included. The strength of evidence was weighed, taking full consideration of any risks of bias, as well as any imprecision, inconsistency, and indirectness of the available data. The strength of each recommendation and the quality of evidence were adjudicated. Trade-offs between desirable and undesirable consequences of alternative management strategies were considered, as were values, preferences, and resource availability. These guidelines were externally reviewed by experts, modified based on those reviews, and will be updated as new knowledge is acquired.

Differential clinical characteristics and prognosis of intraventricular conduction defects in patients with chronic heart failure

AIMS

Intraventricular conduction defects (IVCDs) can impair prognosis of heart failure (HF), but their specific impact is not well established. This study aimed to analyse the clinical profile and outcomes of HF patients with LBBB, right bundle branch block (RBBB), left anterior fascicular block (LAFB), and no IVCDs.

METHODS AND RESULTS

Clinical variables and outcomes after a median follow-up of 21 months were analysed in 1762 patients with chronic HF and LBBB (n = 532), RBBB (n = 134), LAFB (n = 154), and no IVCDs (n = 942). LBBB was associated with more marked LV dilation, depressed LVEF, and mitral valve regurgitation. Patients with RBBB presented overt signs of congestive HF and depressed right ventricular motion. The LAFB group presented intermediate clinical characteristics, and patients with no IVCDs were more often women with less enlarged left ventricles and less depressed LVEF. Death occurred in 332 patients (interannual mortality = 10.8%): cardiovascular in 257, extravascular in 61, and of unknown origin in 14 patients. Cardiac death occurred in 230 (pump failure in 171 and sudden death in 59). An adjusted Cox model showed higher risk of cardiac death and pump failure death in the LBBB and RBBB than in the LAFB and the no IVCD groups.

CONCLUSION

LBBB and RBBB are associated with different clinical profiles and both are independent predictors of increased risk of cardiac death in patients with HF. A more favourable prognosis was observed in patients with LAFB and in those free of IVCDs. Further research in HF patients with RBBB is warranted.