Left Bundle Branch Area Pacing versus Biventricular Pacing for Cardiac Resynchronization Therapy on Morbidity and Mortality

BACKGROUND

Left bundle branch area pacing (LBBAP) has emerged as an alternative to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT). We aimed to compare the morbidity and mortality associated with LBBAP versus BVP in patients undergoing CRT implantation.

METHODS

Consecutive patients who received CRT from two high-volume implantation centers were retrospectively recruited. The primary endpoint was a composite of all-cause death and heart failure hospitalization, and the secondary endpoint was all-cause death.

RESULTS

A total of 491 patients receiving CRT (154 via LBBAP and 337 via BVP) were included, with a median follow-up of 31 months. The primary endpoint was reached by 21 (13.6%) patients in the LBBAP group, as compared with 74 (22.0%) patients in the BVP group [hazard ratio (HR) 0.70, 95% confidence interval (CI) 0.43-1.14, P = 0.15]. There were 10 (6.5%) deaths in the LBBAP group, as compared with 31 (9.2%) in the BVP group (HR 0.91, 95% CI 0.44-1.86, P = 0.79). No significant difference was observed in the risk of either the primary or secondary endpoint between LBBAP and BVP after multivariate Cox regression (HR 0.74, 95% CI 0.45-1.23, P = 0.24, and HR 0.77, 95% CI 0.36-1.67, P = 0.51, respectively) or propensity score matching (HR 0.72, 95% CI 0.41-1.29, P = 0.28, and HR 0.69, 95% CI 0.29-1.65, P = 0.40, respectively).

CONCLUSION

LBBAP was associated with a comparable effect on morbidity and mortality relative to BVP in patients with indications for CRT.

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.

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.

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.

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.

Electrocardiographic Findings in Coronavirus Disease-19: Insights on Mortality and Underlying Myocardial Processes

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a respiratory syndrome with high rates of mortality, and there is a need for easily obtainable markers to provide prognostic information. We sought to determine whether the electrocardiogram (ECG) on hospital presentation provides prognostic information, specifically related to death.

METHODS AND RESULTS

We performed a retrospective cohort study in patients with COVID-19 who had an ECG at or near hospital admission. Clinical characteristics and ECG variables were manually abstracted from the electronic health record and first ECG. Our primary outcome was death.

THERE WERE

756 patients who presented to a large New York City teaching hospital with COVID-19 who underwent an ECG. The mean age was 63.3 ± 16 years, 37% were women, 61% of patients were nonwhite, and 57% had hypertension; 90 (11.9%) died. In a multivariable logistic regression that included age, ECG, and clinical characteristics, the presence of one or more atrial premature contractions (odds ratio [OR] 2.57, 95% confidence interval [CI] 1.23-5.36, P = .01), a right bundle branch block or intraventricular block (OR 2.61, 95% CI 1.32-5.18, P = .002), ischemic T-wave inversion (OR 3.49, 95% CI 1.56-7.80, P = .002), and nonspecific repolarization (OR 2.31, 95% CI 1.27-4.21, P = .006) increased the odds of death. ST elevation was rare (n = 5 [0.7%]).

CONCLUSIONS

We found that patients with ECG findings of both left-sided heart disease (atrial premature contractions, intraventricular block, repolarization abnormalities) and right-sided disease (right bundle branch block) have higher odds of death. ST elevation at presentation was rare.

All-Cause Mortality for Life Insurance Applicants with the Presence of Bundle Branch Block

Objective.-To determine the all-cause mortality of life insurance applicants who have a bundle branch block. Background.-Bundle branch block is an electrocardiographic pattern that has variable prognostic implications. Research studies have shown that both left and right bundle branch block are associated with increased mortality among cases that have heart disease. In the general population and life insurance applicant population, the prevalence of bundle branch block is relatively low, and its effects on long-term prognosis are not as well established. Methodology.-Life insurance applicants with reported bundle branch block were extracted from data covering United States residents between October 2009 and October 2016. Information about these applicants was matched to the Social Security Death Master (SSDMF) file for deaths occurring from 2009 to 2012 and to another commercially available death source file (Other Death Source, ODS) for deaths occurring from 2009 to 2016 to determine vital status. Actual to expected (A/E) mortality ratios were calculated using the Society of Actuaries 2015 Valuation Basic Table (2015VBT), select and ultimate table (age last birthday). All expected bases were not smoker distinct. Confidence bands around these mortality ratios were calculated. The variables of interest were applicant age, gender, location of the bundle branch block, and the presence of cardiac or cardiovascular conditions. Results.-There were 258,529.85 person-years exposure for applicants with bundle branch block. Of the applicants, 57.2% had right bundle branch block. Of person-years exposure, 11.5% had a cardiac condition along with the bundle branch block, and 4.4% had an underlying cardiovascular condition. Female mortality ratios were higher than those for males, but due to the low number of deaths, this difference was not significant. Left bundle branch block mortality ratios (1.01) were 1.4 times higher than those with right (0.74). Those applicants with a cardiac condition along with their bundle branch block had between 1.6 to 1.8 times the mortality ratio depending on the bundle branch block location, and those with a cardiovascular condition had between 1.5 to 1.7 times the mortality ratio over those applicants with just bundle branch block alone. Conclusion.-The presence of bundle branch block in an insurance applicant may be associated with increased all-cause mortality. In this study, life insurance applicants overall had a mortality slightly lower than the expected mortality based on the 2015 VBT. However, applicants with bundle branch block and a cardiac or cardiovascular comorbid condition had a significantly higher mortality ratio.

Association of cardiac implantable electronic devices with survival in bifascicular block and prolonged PR interval on electrocardiogram

PURPOSE

Bifascicular block and prolonged PR interval on the electrocardiogram (ECG) have been associated with complete heart block and sudden cardiac death. We sought to determine if cardiac implantable electronic devices (CIED) improve survival in these patients.

METHODS

We assessed survival in relation to CIED status among 636 consecutive patients with bifascicular block and prolonged PR interval on the ECG. In survival analyses, CIED was considered as a time-varying covariate.

RESULTS

Average age was 76 ± 9 years, and 99% of the patients were men. A total of 167 (26%) underwent CIED (127 pacemaker only) implantation at baseline (n = 23) or during follow-up (n = 144). During 5.4 ± 3.8 years of follow-up, 83 (13%) patients developed complete or high-degree atrioventricular block and 375 (59%) died. Patients with a CIED had a longer survival compared to those without a CIED in the traditional, static analysis (log-rank p < 0.0001) but not when CIED was considered as a time-varying covariate (log-rank p = 0.76). In the multivariable model, patients with a CIED had a 34% lower risk of death (hazard ratio 0.66, 95% confidence interval 0.52-0.83; p = 0.001) than those without CIED in the traditional analysis but not in the time-varying covariate analysis (hazard ratio 1.05, 95% confidence interval 0.79-1.38; p = 0.76). Results did not change in the subgroup with a pacemaker only.

CONCLUSIONS

Bifascicular block and prolonged PR interval on ECG are associated with a high incidence of complete atrioventricular block and mortality. However, CIED implantation does not have a significant influence on survival when time-varying nature of CIED implantation is considered.

Ventricular Electrical Delay Measured From Body Surface ECGs Is Associated With Cardiac Resynchronization Therapy Response in Left Bundle Branch Block Patients From the MADIT-CRT Trial (Multicenter Automatic Defibrillator Implantation-Cardiac Resynchronization Therapy)

BACKGROUND

Although cardiac resynchronization therapy (CRT) is beneficial in heart failure patients with left bundle branch block, 30% of these patients do not respond to the therapy. Identifying these patients before implantation of the device is one of the current challenges in clinical cardiology.

METHODS

We verified the diagnostic contribution and an optimized computerized approach to measuring ventricular electrical activation delay (VED) from body surface 12-lead ECGs. We applied the method to ECGs acquired before implantation (baseline) in the MADIT-CRT trial (Multicenter Automatic Defibrillator Implantation-Cardiac Resynchronization Therapy). VED values were dichotomized using its quartiles, and we tested the association of VED values with the MADIT-CRT primary end point of heart failure or death. Multivariate Cox proportional models were used to estimate the risk of study end points. In addition, the association between VED values and hemodynamic changes after CRT-D implantation was examined using 1-year follow-up echocardiograms.

RESULTS

Our results showed that left bundle branch block patients with baseline VED <31.2 ms had a 35% risk of MADIT-CRT end points, whereas patients with VED ≥31.2 ms had a 14% risk (P<0.001). The hazard ratio for predicting primary end points in patients with low VED was 2.34 (95% confidence interval, 1.53-3.57; P<0.001). Higher VED values were also associated with beneficial hemodynamic changes. These strong VED associations were not found in the right bundle branch block and intraventricular conduction delay cohorts of the MADIT-CRT trial.

CONCLUSIONS

Left bundle branch block patients with a high baseline VED value benefited most from CRT, whereas left bundle branch block patients with low VED did not show CRT benefits.

Association Between Global Longitudinal Strain and Cardiovascular Events in Patients With Left Bundle Branch Block Assessed Using Two-Dimensional Speckle-Tracking Echocardiography

BACKGROUND

The prognostic value of left ventricular (LV) global strain and twist in patients with left bundle branch block (LBBB) is not fully investigated. The aim of this study was to investigate the association between myocardial strain and twist and cardiovascular events in patients with LBBB, as assessed using two-dimensional speckle-tracking echocardiography.

METHODS

A total of 269 patients with LBBB (mean age, 69.5 ± 10.9 years; 46.8% men) were retrospectively identified. Using speckle-tracking, LV global longitudinal strain (GLS), global circumferential strain, and twist were measured. Association between LV global function and a composite of cardiovascular mortality and hospitalization for heart failure was compared with clinical risk factors, LV ejection fraction (LVEF), and other echocardiographic parameters.

RESULTS

During a median of 27.5 months (interquartile range, 12.8-43.9 months), the composite end point occurred in 55 patients (20.4%). In univariate analyses, diabetes mellitus, chronic kidney disease, ischemic etiology of LBBB, dilated left atrium, reduced LVEF, dilated left ventricle, and impaired LV global strain (GLS > -12.2%, global circumferential strain > -11.8%, and twist < 6.5°) showed associations with the composite end point. In multivariate analyses, GLS was significantly associated with the composite end point (adjusted hazard ratio, 4.697; 95% CI, 1.344-16.413; P = .015), whereas global circumferential strain, twist, and LVEF were not. GLS showed an additive association with poor prognosis over clinical risk factors and other echocardiographic parameters, including LVEF. Patients with preserved LVEFs (≥40%) but impaired GLS (>-12.2%) had a larger number of clinical events than those with impaired LVEFs but preserved GLS.

CONCLUSIONS

Among patients with LBBB, GLS can provide better risk stratification than LVEF or other echocardiographic parameters.

Is there a prognostic relevance of electrophysiological studies in bundle branch block patients?

BACKGROUND

The present European guidelines suggest a diagnostic electrophysiological (EP) study to determine indication for cardiac pacing in patients with bundle branch block and unexplained syncope. We evaluated the prognostic relevance of an EP study for mortality and the development of permanent complete atrioventricular (AV) block in patients with symptomatic bifascicular block and first-degree AV block.

HYPOTHESIS

The HV interval is a poor prognostic marker to predict the development of permanent AV block in patients with symptomatic bifascicular block (BFB) and AV block I°.

METHODS

Thirty consecutive patients (mean age, 74.8 ± 8.6 years; 25 males) with symptomatic BFB and first-degree AV block underwent an EP study before device implantation, according to current guidelines. For 53 ± 31 months, patients underwent yearly follow-up screening for syncope or higher-degree AV block.

RESULTS

Thirty patients presented with prolonged HV interval during the EP study (mean, 82.2 ± 20.1 ms; range, 57-142 ms), classified into 3 groups: group 1, <70 ms (mean, 62 ± 4 ms; range, 57-67 ms; n = 7), group 2, >70 to ≤100 ms (mean, 80 ± 8 ms; range, 70-97 ms; n = 18), and group 3, >100 ms (mean, 119 ± 14 ms; range, 107-142 ms; n = 5). According to the guidelines, patients in groups 2 and 3 received a pacemaker. The length of the HV interval was not associated with the later development of third-degree AV block or with increased mortality.

CONCLUSIONS

Our present study suggests that an indication for pacemaker implantation based solely on a diagnostic EP study with prolongation of the HV interval is not justified.

Incidence and predictors of sudden death, major conduction defects and sustained ventricular tachyarrhythmias in 1388 patients with myotonic dystrophy type 1

AIMS

To describe the incidence and identify predictors of sudden death (SD), major conduction defects and sustained ventricular tachyarrhythmias (VTA) in myotonic dystrophy type 1 (DM1).

METHODS AND RESULTS

We retrospectively enrolled 1388 adults with DM1 referred to six French medical centres between January 2000 and October 2013. We confirmed their vital status, classified all deaths, and determined the incidence of major conduction defects requiring permanent pacing and sustained VTA. We searched for predictors of overall survival, SD, major conduction defects, and sustained VTA by Cox regression analysis. Over a median 10-year follow-up, 253 (18.2%) patients died, 39 (3.6%) suddenly. Analysis of the cardiac rhythm at the time of the 39 SD revealed sustained VTA in 9, asystole in 5, complete atrioventricular block in 1 and electromechanical dissociation in two patients. Non-cardiac causes were identified in the five patients with SD who underwent autopsies. Major conduction defects developed in 143 (19.3%) and sustained VTA in 26 (2.3%) patients. By Cox regression analysis, age, family history of SD and left bundle branch block were independent predictors of SD, while age, male sex, electrocardiographic conduction abnormalities, syncope, and atrial fibrillation were independent predictors of major conduction defects; non-sustained VTA was the only predictor of sustained VTA.

CONCLUSIONS

SD was a frequent mode of death in DM1, with multiple mechanisms involved. Major conduction defects were by far more frequent than sustained VTA, whose only independent predictor was a personal history of non-sustained VTA. ClinicalTrials.gov no: NCT01136330.

Permanent His-bundle pacing in patients with prosthetic cardiac valves

BACKGROUND

Conduction disease is not uncommon after prosthetic valve (PV) surgery. The feasibility of His-bundle pacing (HBP) in this patient population is not well studied.

OBJECTIVE

The purpose of this study was to report our experience with permanent HBP in patients undergoing pacemaker implantation after PV surgery.

METHODS

Permanent HBP was attempted in patients with AV conduction disease after PV surgery referred for pacemaker implantation. Conduction disease was characterized as AV nodal vs infranodal. Feasibility, relationship of HBP lead to PVs, and HBP characteristics were recorded.

RESULTS

Thirty patients (47% men, age 74 ± 12 years, left ventricular ejection fraction 49% ± 11%) with AV conduction disease (100% patients; 14 with infranodal block; right bundle branch block 9, left bundle branch block 5, intraventricular conduction delay 1) underwent HBP. PVs included aortic valve replacement (AVR) in 8 patients (infranodal block 6 patients), tricuspid valve (TV) ring with mitral valve replacement or repair (MVR) in 10 patients (AV nodal block 9 patients), transcatheter aortic valve replacement (TAVR) in 4 patients (infranodal block 4 patients), and MVR alone in 6 patients. HBP was successful in 28 patients (93%) (selective HBP 50%). His bundle (HB) recruitment was unsuccessful in 2 patients with TAVR. AVR/TAVR and TV ring served as anatomic landmarks for localizing the HB. Successful sites of HBP were posterior and inferior to AVR/TAVR and distal and septal to the TV ring. Baseline QRSd improved from 124 ± 32 ms to 118 ± 20 ms (P = .39). HBP threshold at implant was 1.45 ± 1 V at 1 ms.

CONCLUSION

Permanent HBP was feasible in 93% of patients with PVs. Patients with AVR/TAVR predominantly developed infranodal block compared to AV nodal block in patients with TV ring/MVR. Location of PV might serve as a landmark for identifying the site of the HB.

Right Bundle Branch Block in Acute Myocardial Infarction Treated by Primary Coronary Angioplasty and Stenting

Patients with right bundle branch block (RBBB) in acute myocardial infarction (AMI) have a significantly higher mortality rate even with the advent of thrombolytic therapy. This study was undertaken to assess the impact of primary percutaneous transluminal coronary angioplasty (PTCA) and stenting on the outcome of patients with RBBB in AMI. A total of 600 patients with AMI who underwent primary PTCA and stenting (rate: 61%) <12 hours of onset were studied. A 12-lead ECG was obtained at least every 6 hours. Serial creatine kinase was measured, and left ventricular ejection fraction was obtained during the hospital stay. Among 600 patients with AMI, 94 patients (15.7%) had RBBB; it was persistent in 31 (33%) and transient in 63 (67%). In-hospital mortality rate was 7.3% in patients without RBBB, 7.9% in transient RBBB, and 25.8% in persistent RBBB (p<0.02). The incidence of heart failure was 26.5% in those without RBBB, 34.9% in transient RBBB, and 58.1% in persistent RBBB (p<0.001). There was no significant difference among these 3 groups in ventricular arrhythmias and complete atrioventricular block. Peak creatine kinase was 3,214 ±2,293 U/L in those without RBBB, 4,558 ±3,316 U/L in transient RBBB (p<0.001), and 5,635 ±3,920 U/L in persistent RBBB (p<0.001). Left ventricular ejection fraction was 50 ±11% in those without RBBB, 47 ±11% in transient RBBB (p<0.05), and 42 ±13% in persistent RBBB (p<0.001). Patients with AMI treated by primary PTCA and stenting had an increased incidence of transient RBBB, especially following reperfusion therapy, although the clinical outcome was similar to that of those without RBBB. In contrast, there was no satisfactory improvement in clinical outcomes in those with persistent RBBB.

Cardiac Resynchronization Therapy in Women

The benefits of cardiac resynchronization therapy (CRT) on the outcomes of patients with heart failure are unquestionable. Women are under-represented in all CRT studies. Most of the available data show that CRT produces a greater clinical benefit in women than men. In several studies, women have left bundle branch block more frequently than men. Women have a remarkably high (90%) CRT response over a wide range of QRS lengths (130-175 milliseconds). Use of a QRS duration of 150 milliseconds as the threshold for CRT prescription may deny a life-saving therapy to many women likely to benefit from CRT.

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.

Impact on Left Ventricular Function and Remodeling and on 1-Year Outcome in Patients With Left Bundle Branch Block After Transcatheter Aortic Valve Implantation

Conflicting results have been reported about the prognostic impact of left bundle branch block (LBBB) after transcatheter aortic valve implantation (TAVI). The aim of this study was to evaluate the impact of LBBB after TAVI on left ventricular (LV) function and remodeling and on 1-year outcomes. Of 101 TAVI patients, 9 were excluded. All complications were evaluated according to the Valve Academic Research Consortium 2 definition. Of 92 patients, 34 developed LBBB without more advanced myocardial damage or inflammation biomarkers in comparison with patients without LBBB. The only predictor of new LBBB was larger baseline LV end-diastolic volume. LBBB plus advanced atrioventricular block was strongly correlated with permanent pacemaker implantation (p <0.0001). Patients with LBBB had a higher rate of permanent pacemaker implantation at 30 days (59% vs 19%, p <0.0001) and less recovery of LV systolic function and a trend toward a lower rate of LV reverse remodeling at 1 year. The development of acute kidney injury and the logistic European System for Cardiac Operative Risk Evaluation score were associated with poor outcomes (all-cause mortality and heart failure) (hazard ratio 6.86, 95% confidence interval 2.51 to 18.74, p <0.0001, and hazard ratio 1.04, 95% confidence interval 1.01 to 1.08, p = 0.021, respectively), but not LBBB. In conclusion, after TAVI, 37% of patients developed new LBBB without more advanced myocardial damage or inflammation biomarkers. LBBB was associated with a higher rate of permanent pacemaker implantation, which negatively affected the recovery of LV systolic function. The development of acute kidney injury, rather than LBBB, increases the 1-year risk for mortality and hospitalization for heart failure.

Usefulness of QRS axis change to predict mortality in patients with left bundle branch block

QRS duration correlates with poor prognosis in patients with left bundle branch block (LBBB), but the importance of left-axis deviation (LAD) is not well established. To determine if LAD confers a mortality risk in patients with LBBB, a single-center, retrospective, population-based cohort study was conducted. Included were all patients at 1 hospital with LBBB on electrocardiography from 1995 to 2005 over a 17-year follow-up period (n = 2,794, median follow-up duration 20 months, interquartile range 6 to 64). Half of all patients with LBBB had LAD. The all-cause mortality rate in the entire cohort was 15%. LAD was not associated with mortality, either as a single outcome (odds ratio [OR] 1.1, 95% confidence interval [CI] 0.88 to 1.3, p = 0.50) or in time-to-event analysis (p = 0.40). Significant risk factors for mortality included high creatinine (OR 1.2, 95% CI 1.1 to 1.3), low hemoglobin (OR 1.2, 95% CI 1.1 to 1.3), history of atrial fibrillation (OR 1.6, 95% CI 1.3 to 2.1), electrocardiographic evidence of previous infarct (OR 1.5, 95% CI 1.2 to 1.9), and history of ventricular tachycardia (OR 1.4, 95% CI 1.0 to 1.9). On bivariate analysis, LAD was associated with atrial fibrillation, ventricular tachycardia, age, and congestive heart failure. Patients with LBBB who converted from normal axis to LAD had significantly higher mortality in time-to-event analysis (p = 0.02). In conclusion, in patients with LBBB, LAD does not confer significant mortality risk. However, those with normal axis who developed LAD during the study period had significantly higher mortality. Perhaps when LBBB and LAD develop concurrently, there is no increased risk over baseline LBBB development, but it may herald a worse prognosis if LAD develops against the background of previous LBBB, from an unknown mechanism.

Comparison of functional recovery following percutaneous coronary intervention for ST elevation myocardial infarction in three age groups (<70, 70 to 79, and ≥80 years)

Functional outcomes of elderly patients ≥80 years who undergo percutaneous coronary intervention (PCI) for ST elevation myocardial infarction (STEMI) are unknown. Registry data indicate that up to 55% of elderly patients with STEMI do not receive reperfusion therapy despite a suggested mortality benefit, and only limited data are available regarding outcomes in elderly patients treated with primary PCI. Therefore, prospective data from a regional STEMI transfer program were analyzed to determine major adverse cardiac events, length of stay, and discharge status of consecutive patients with STEMI ≥80 years from March 2003 to November 2006. Of the 1,323 consecutive patients with STEMI treated in this regional STEMI system from March 2003 to November 2006, 199 (15.0%) were ≥80 years old. In-hospital mortality in elderly patients was 11.6%, with a 1-year mortality rate of 25.6%. Of the 166 patients with age ≥80 who lived independently or in assisted living before hospital admission and survived, 150 (90.4%) were discharged to a similar living situation or projected to such a living situation after temporary nursing home care. The median length of hospital stay was 4 days for these patients. In conclusion, elderly patients with age ≥80 receiving PCI for STEMI in a regional STEMI program have short hospital stays and excellent functional recovery on the basis of a very high rate of return to a similar previous living situation.

Prognostic importance of electrocardiographic abnormalities in patients with acute noncardiac conditions

The electrocardiogram's (ECG) ability to aid in the diagnosis and risk stratification of patients with acute coronary syndromes is well established. We sought to investigate the prognostic significance of ECG abnormalities in patients with noncardiac conditions in the emergency department. Patients presenting to the emergency department who were evaluated for possible acute coronary syndrome were consecutively enrolled and an initial ECG was obtained (n = 1024). Only patients with noncardiac diagnoses were reviewed in this analysis (n=493) and 30-month follow-up was obtained. Sinus tachycardia, atrial fibrillation/flutter, ST depression, and left bundle branch block were associated with increased 30-month mortality. After controlling for history of coronary artery disease, age, sex, diabetes mellitus, hypertension, and renal insufficiency, sinus tachycardia and ST-segment depression ≥1 mm were independent predictors of 30-month mortality with a hazard ratio of 2.33 (95% confidence interval, 1.36-4.00; P = 0.002) and 2.49 (95% confidence interval, 1.10-5.67; P = 0.029), respectively. In conclusion, ST-segment depression and sinus tachycardia in patients presenting to the hospital with noncardiac conditions are independently associated with increased 30-month mortality.

Left Bundle-Branch Block Induced by Transcatheter Aortic Valve Implantation Increases Risk of Death

Background—

Transcatheter aortic valve implantation (TAVI) is a novel therapy for treatment of severe aortic stenosis. Although 30% to 50% of patients develop new left bundle-branch block (LBBB), its effect on clinical outcome is unclear.

Methods and Results—

Data were collected in a multicenter registry encompassing TAVI patients from 2005 until 2010. The all-cause mortality rate at follow-up was compared between patients who did and did not develop new LBBB. Of 679 patients analyzed, 387 (57.0%) underwent TAVI with the Medtronic CoreValve System and 292 (43.0%) with the Edwards SAPIEN valve. A total of 233 patients (34.3%) developed new LBBB. Median follow-up was 449.5 (interquartile range, 174–834) days in patients with and 450 (interquartile range, 253–725) days in patients without LBBB ( P =0.90). All-cause mortality was 37.8% (n=88) in patients with LBBB and 24.0% (n=107) in patients without LBBB ( P =0.002). By multivariate regression analysis, independent predictors of all-cause mortality were TAVI-induced LBBB (hazard ratio [HR], 1.54; confidence interval [CI], 1.12–2.10), chronic obstructive lung disease (HR, 1.56; CI, 1.15–2.10), female sex (HR, 1.39; CI, 1.04–1.85), left ventricular ejection fraction ≤50% (HR, 1.38; CI, 1.02–1.86), and baseline creatinine (HR, 1.32; CI, 1.19–1.43). LBBB was more frequent after implantation of the Medtronic CoreValve System than after Edwards SAPIEN implantation (51.1% and 12.0%, respectively; P <0.001), but device type did not influence the mortality risk of TAVI-induced LBBB.

Conclusions—

All-cause mortality after TAVI is higher in patients who develop LBBB than in patients who do not. TAVI-induced LBBB is an independent predictor of mortality.

[Prehospital thrombolysis acute coronary syndrome in patients with acute left bundle branch block]

Analyzed 30-days survival in 18 patients after a system of dark prehospital thrombolysis performed for an acute coronary syndrome (ACS) with acute left bundle branch block (LBBB). Survival after thrombolytic therapy (TLT) was 4 times higher than in patients with acute coronary syndrome and acute blockade LBBB without TLT. It is concluded that thrombolytic therapy leads to a reduction of the QRS complex in 66% of patients.

Prognostic impact of electrocardiographic signs in patients with Type 2 diabetes and cardiovascular disease: results from the PROactive study

AIMS

Although a resting electrocardiograph is broadly applied in clinical practice for evaluating patients with Type 2 diabetes and cardiovascular disease, the independent prognostic relevance of electrocardiographic signs has not thoroughly been examined.

METHODS

Baseline 12-lead electrocardiographs available in 5231 of the 5238 participants of the PROactive trial were analysed for heart rate, heart rate corrected QT-interval, presence of atrial fibrillation/flutter, left axis deviation, right and left bundle branch block. The association of electrocardiographic signs with total mortality, the principal secondary composite endpoint (death, myocardial infarction and stroke) and serious adverse heart failure events was examined by Cox-regression analysis.

RESULTS

Two hundred and twenty-three (4.3%) patients showed atrial fibrillation/flutter, 213 (4.1%) patients had right bundle branch block, 111 (2.1%) patients had left bundle branch block and 706 (13.5%) patients had left axis deviation. Mean cQT-interval was 418 ms (± 25 ms) and mean heart rate was 72/min (± 14/min). In multivariate adjusted analyses, heart rate and cQT-interval were significantly associated with mortality, the composite secondary endpoint and heart failure, whereas right and left bundle branch blocks were significantly associated with heart failure only. Left axis deviation was associated with heart failure and atrial fibrillation/flutter was associated with mortality and heart failure in univariate but not multivariate analyses.

CONCLUSION

Easily assessable electrocardiographic signs such as heart rate, cQT-interval and bundle branch blocks were predictive for adverse outcome independently of multiple risk factor adjustment and should be considered in clinical care.

[Cardiac resynchronisation therapy : new data and technical developments]

Cardiac resynchronisation therapy (CRT) has opened up new perspectives over the past 10 years for highly symptomatic patients with severe systolic heart failure. The present article analyses and comments on recent publications which have lead to an expansion of the indication to patients with mild symptoms of heart failure, and which resulted in the modification of current European guidelines in 2010. The data available from narrow QRS complex studies are critically examined. Furthermore, the latest technical innovations in the field of CRT, which have helped to ease the implantation procedure and achieve higher success rates, are presented. Finally, new wireless ultrasound technology to stimulate the left ventricle, currently in an early clinical phase of evaluation, is presented as a potential alternative in the future.

Impact of a well-organized collaborative team approach on mortality in patients with ST-segment elevation myocardial infarction

OBJECTIVE

Fibrinolytic therapy remains a legitimate option for many patients presenting with acute ST-segment elevation myocardial infarction (STEMI). Shorter time- to- treatment for patients with STEMI administered fibrinolytic therapy has repeatedly been shown to reduce mortality. A well-organized collaborative team approach was implemented in April 2007. The purpose of this study was to examine the effect of implementing a well-organized collaborative team approach on the outcome in patients with acute STEMI treated with fibrinolysis.

METHODS

Sociodemographic, clinical, laboratory, and time interval data were prospectively collected on 109 consecutive patients (the study group) and 155 patients from the years 2005-2007 (the control group) retrospectively. A single-phone call was made to discuss case. Emergency department evaluation was bypassed for definitive case. An electrocardiogram was faxed to the on-call cardiologist for suspected case. Door-to-needle times were calculated as medians. Mortality was assessed by reviewing records of all patients visiting outpatient clinic. For the rest, information was obtained over the phone. Median door-to-needle times were compared using Mann-Whitney U test. The Fisher's exact test was used to compare 6-month mortalities.

RESULTS

Improvements were seen in door-to- needle times in the study group regardless of time of presentation (reduced from 59 minutes to 29 minutes during off hours) (reduced from 35 minutes to 18 minutes during regular hours) (p<0.0001). Mortality was significantly reduced in the study group (2 deaths, 1.8%) compared with the control group (12 deaths, 7.7%, p=0.048).

CONCLUSION

The mortality of patients presenting with acute STEMI treated with fibrinolytic therapy was significantly reduced after optimal hospital organization.

Prognostic value of lead V1 ST elevation during acute inferior myocardial infarction

BACKGROUND

Lead V(1) directly faces the right ventricle and may exhibit ST elevation during an acute inferior myocardial infarction when the right ventricle is also involved. Leads V(1) and V(3) indirectly face the posterolateral left ventricle, and ST depression ("mirror-image" ST elevation) in V(1) through V(3) may reflect concomitant posterolateral infarction. The prognostic significance of V(1) ST elevation during an acute inferior myocardial infarction may therefore be dependent on V(3) ST changes.

METHODS AND RESULTS

In 7967 patients with acute inferior myocardial infarction in the Hirulog and Early Reperfusion or Occlusion-2 (HERO-2) trial, V(1) ST levels were analyzed with adjustment for lead V(3) ST level for predicting 30-day mortality. V(1) ST elevation at baseline, analyzed as a continuous variable, was associated with higher mortality. Unadjusted, each 0.5-mm-step increase in ST level above the isoelectric level was associated with approximately 25% increase in 30-day mortality; this was true whether V(3) ST depression was present or not. The odds ratio for mortality was 1.21 (95% confidence interval, 1.07 to 1.37) after adjustment for inferolateral ST elevation and clinical factors and 1.24 (95% confidence interval, 1.09 to 1.40) if also adjusted for V(3) ST level. In contrast, lead V(1) ST depression was not associated with mortality after adjustment for V(3) ST level. V(1) ST elevation >or=1 mm, analyzed dichotomously in all patients, was associated with higher mortality. The odds ratio was 1.28 (95% confidence interval, 1.01 to 1.61) unadjusted, 1.51 (95% confidence interval, 1.19 to 1.92) adjusted for V(3) ST level, and 1.35 (95% confidence interval, 1.04 to 1.76) adjusted for ECG and clinical factors. Persistence of V(1) ST elevation >or=1 mm 60 minutes after fibrinolysis was associated with higher mortality (10.8% versus 5.5%, P=0.001).

CONCLUSIONS

V(1) ST elevation identifies patients with acute inferior myocardial infarction who are at higher risk.

In-hospital outcome in patients with ST elevation myocardial infarction and right bundle branch block. A sub-study from RENASICA II, a national multicenter registry

OBJECTIVE

Compare in-hospital outcome in patients with ST-elevation myocardial infarction with right versus left bundle branch block.

METHODS

RENASICA II, a national Mexican registry enrolled 8098 patients with final diagnosis of acute coronary syndrome secondary to ischemic heart disease. In 4555 STEMI patients, 545 had bundle branch block, 318 (58.3%) with right and 225 patients with left (41.6%). Both groups were compared in terms of in-hospital outcome through major cardiovascular adverse events; (cardiovascular death, recurrent ischemia and reinfarction). Multivariable analysis was performed to identify in-hospital mortality risk among right and left bundle branch block patients.

RESULTS

There were not statistical differences in both groups regarding baseline characteristics, time of ischemia, myocardial infarction location, ventricular dysfunction and reperfusion strategies. In-hospital outcome in bundle branch block group was characterized by a high incidence of major cardiovascular adverse events with a trend to higher mortality in patients with right bundle branch block (OR 1.70, CI 1.19 - 2.42, p < 0.003), compared to left bundle branch block patients.

CONCLUSION

In this sub-study right bundle branch block accompanying ST-elevation myocardial infarction of any location at emergency room presentation was an independent predictor of high in-hospital mortality.

Complete right bundle branch block predicts mortality in Thai patients with chronic heart failure with reduced ejection fraction

BACKGROUND

Previous studies have shown that intraventricular conduction defect is associated with increased mortality in heart failure (HF) population. However, it is conflicting whether left bundle branch block (LBBB) or right bundle branch block (RBBB) is a better predictor for mortality.

OBJECTIVE

To evaluate the relationship between patterns of bundle branch block (BBB) and all-cause mortality in Thai patients with chronic heart failure with reduced ejection fraction (HFrEF) and to compare the prognostic values of RBBB and LBBB in this population.

MATERIAL AND METHOD

The authors retrospectively studied a cohort of 170 patients (age 58 +/- 14 years, male=117) with HFrEF requiring hospitalization and were followed-up in a heart failure clinic. Predictors of mortality were evaluated by Cox proportional hazard analysis.

RESULTS

Wide QRS complex (duration >120 ms) was present in 26% of patients, 15% with LBBB, 11% with RBBB. During an average follow-up of 1.8 +/-1.6 years, 22 patients (13%) died. By univariate analysis, presence of chronic renal insufficiency, chronic obstructive pulmonary disease, severe left ventricular systolic dysfunction and RBBB, but not LBBB were associated with increased mortality. After multivariate adjustment, the presence of RBBB was the only strong predictor of mortality in HF patients (OR 3.9, 95% CI 1.3-11.7, p < 0.05).

CONCLUSION

The presence of RBBB was the only independent predictor of mortality in Thai patients with HFrEE

Long-term clinical response of cardiac resynchronization after chronic right ventricular pacing

Chronic right ventricular (RV) pacing might elicit unpredictably deleterious effects on left ventricular (LV) function similar to that of native left bundle branch block (LBBB). The objective of the present study was to evaluate the clinical and echocardiographic response to cardiac resynchronization therapy after years of chronic RV pacing. In this prospective observational study of 284 consecutive patients, cardiac resynchronization therapy was performed in 194 patients (68%) with a native LBBB and in 90 patients (32%) with a pacing-induced LBBB after chronic RV pacing (upgraded group). Echocardiographic and clinical parameters were evaluated in both groups at baseline and during 2 years of follow-up. The clinical response was defined as survival with improvement of > or =1 in the New York Heart Association class without heart failure hospitalization. Reverse LV remodeling was defined as LV end-systolic volume reduction of > or =15%. At baseline, the New York Heart Association class, quality of life, and exercise capacity were comparable but the LV ejection fraction was significant greater and the LV volumes were significant smaller in the upgraded group. Changes with time in the clinical parameters, echocardiographic parameters, and clinical response were not significantly different between the 2 groups. Reverse LV remodeling was observed in 86% in the upgraded group versus 78% of the native LBBB group after 1 year (p = 0.39). Survival was not significantly different between the 2 groups. In conclusion, comparable clinical and echocardiographic improvement was seen when resynchronization therapy was applied in patients with preceding chronic RV pacing compared with patients with a native LBBB.

Prognostic significance of bundle-branch block in acute myocardial infarction: the importance of location and time of appearance

BACKGROUND

The presence of bundle-branch block (BBB) is associated with high mortality rates and is considered an important predictor of poor outcome in patients with acute myocardial infarction (AMI).

HYPOTHESIS

The objective of this study was to assess the prognostic significance of BBB in patients with AMI depending on its form of presentation.

METHODS

A multicenter prospective 1-year follow-up study involving 1,239 consecutive patients diagnosed with AMI was performed.

RESULTS

Bundle-branch block was present in 177 cases (14.2%), associated with worse clinical characteristics, lower rate of thrombolytic therapy, and higher mortality: in-hospital (23.8 vs. 9.7%, p < .01) and 1-year (40.9 vs. 16.9%, p < 0.01). Compared with right BBB (n = 135), left BBB (n = 42) was more often associated with female gender and higher prevalence of cardiovascular diseases, but had a similar 1-year mortality. In the absence of heart failure or complete atrioventricular (AV) block, there was no difference in in-hospital mortality of patients with BBB (n = 76) and without BBB (n = 786) (2.6 vs. 3.9%). Compared with existing BBB (n = 113), BBB of new appearance (n = 64) was more often accompanied by complete AV block and heart failure and higher in-hospital and 1-year mortality rates. Only BBB of new appearance was an independent predictor of mortality: in-hospital (odds ratio [OR] 2.3, 95% confidence interval [CI] 1.1-4.7) and 1-year mortality (OR 3.2, 95% CI, 1.7-9.1).

CONCLUSIONS

In patients with AMI, the classification of BBB according not only to location but also to time of appearance is of practical interest. New BBB is an independent predictor of short- and long-term mortality.

[Structural-functional peculiarities of the heart and survival of elderly patients with chronic heart failure and left bundle branch block]

AIM

To study structural-functional characteristics of the heart and survival of elderly patients with chronic heart failure (CHF) and left bundle branch block (LBBB).

MATERIAL AND METHODS

We examined and followed-up 108 patients aged 60-85 years with NYHA class II-IV CHF with and without LBBB.

RESULTS

Patients of both groups were comparable according to sex, age, CHF duration and severity, hemodynamic parameters, clinical condition, quality of life, and spectrum of taken drugs. Patients with LBBB had statistically significant increases of end diastolic (p<0.001) and systolic (p<0.001) dimensions, end diastolic (p<0.001) and systolic (p<0.001) volumes, sphericity index (p<0.001), long axis (p<0.05), decreases of relative thickness of the left ventricle (p<0.05), interventricular septum (p<0.001), and left ventricular ejection fraction (p<0.001). Pronounced mitral regurgitation also was more frequent in patients with LBBB (p<0.01). During follow up 14/34 patients (41.2%) with LBBB and 19/74 patients (25.7%) without LBBB died. There were 10 and 9 sudden deaths among patients with and without LBBB, respectively.

CONCLUSION

In patients with LBBB development of CHF is associated with changes of left ventricular geometry. Sudden death is the most frequent cause of death of these patients.

Prognostic impact of left bundle-branch block in the early stable phase after acute myocardial infarction

BACKGROUND

Diagnostic marker parameters are needed to enable timely identification of high risk patients after acute myocardial infarction (MI). We assessed risk factors for death and sudden death in stable revascularized patients undergoing guideline-based therapy during an in-patient rehabilitation program more than 3 weeks after acute myocardial infarction.

METHODS

During an in-patient rehabilitation program, 939 patients with a recent myocardial infarction were prospectively included. Besides demographic and clinical data, ejection fraction (EF), Holter ECG, standard 12-lead electrocardiogram (ECG) and baseline laboratory values were determined. Patients were followed up for 18 months.

RESULTS

Among multiple variables, left bundle-branch block (LBBB) was the most significant parameter affecting the outcome (combination endpoint of death, resuscitation or ventricular tachycardia (VT)), hazard ratio 7.74 (3.2-18.7, P<0.0001). 42% of the 24 patients with LBBB but only 11.5% of the 62 patients with a left ventricular EF </=30% died during follow-up (P<0.001).

CONCLUSION

LBBB observed during a rehabilitation program following an acute MI indicates a grave prognosis with a high mortality rate (mainly caused by sudden death). Future studies are required to establish whether this simple marker characterizes a group of patients that will profit from preventive defibrillator implantation and/or biventricular pacing.

Influence of left bundle branch block on long-term mortality in a population with heart failure

BACKGROUND

The purpose of this study was to assess the independent contribution of left bundle branch block (LBBB) on long-term mortality in a large cohort with symptomatic heart failure (HF) requiring hospitalization.

METHODS AND RESULTS

We studied a prospective cohort of 21 685 cases of symptomatic HF requiring hospitalization in the Register of Information and Knowledge about Swedish Heart Intensive care Admissions in 1995-2003. Long-term mortality was evaluated by Logistic regression analysis, adjusted for multiple covariates that could influence long-term prognosis. LBBB was present in 20% (4395 of 21 685) of HF admissions. Patients with LBBB had a higher prevalence of cardiac comorbid conditions than patients with no LBBB. 1-, 5-, and 10-year mortality was 31.5 vs. 28.4%, 69.3 vs. 61.3%, and 90.1 vs. 84.7% for HF patients with and without respectively LBBB. When adjusting for comorbidity, LBBB was associated with increased 5-year mortality (OR, 1.21; 95% CI, 1.10-1.35; P < 0.001). When left ventricular ejection fraction was included in the analysis LBBB had no longer any independent influence on 5-mortality (OR, 0.99; 95% CI, 0.62-1.56; P = 0.953).

CONCLUSION

LBBB occurs in 1/5 in HF patients requiring hospitalization and is associated with a very high mortality. However, the high long-term mortality appears to be caused by cardiac comorbidities and myocardial dysfunction rather than the LBBB per se.

Prognostic value of tissue Doppler-derived ventricular asynchrony in patients with left bundle branch block but not advanced heart failure

OBJECTIVES

The aim of the present study was to evaluate the prognostic significance of tissue Doppler echocardiography (TDE)-derived ventricular asynchrony in patients with left bundle branch block (LBBB) but not advanced heart failure.

METHODS

Fifty-five patients (mean age 66 +/- 13 years; 33 male) with complete LBBB (QRS > 120 ms) hospitalized for an acute episode of decompensated heart failure and in New York Heart Association class II for at least 6 months before the study admission underwent standard Doppler echo and pulsed-wave TDE. Precontraction time (PCTm) from the beginning of Q wave of electrocardiogram to the onset of systolic myocardial velocity wave was evaluated in four different left ventricular (LV) basal myocardial segments (LV anterior, inferior, septal and lateral walls) and in one right ventricular (RV) lateral wall. Intraventricular activation delay (IntraV-del) was calculated by the difference of PCTm of each LV myocardial segment. Interventricular activation delay (InterV-del) was calculated by the difference of PCTm between the most delayed LV segment and RV lateral wall.

RESULTS

The mean value of EF was 40 +/- 9% and of InterV-del, IntraV-del was, respectively (97.4 +/- 46.7 and 57.9 +/- 35.5 ms). InterV-del was inversely related to EF (r = -0.68; P < 0001). During the follow-up (26 months, range 11-37 months) cardiac events were recorded in 23 (41%) patients: a worsening of heart failure (WHF) in 23 patients and cardiac death in ten patients. Cox proportional hazard multivariate analysis showed that age, and InterV-del [HR = 1.02 (P < 0.05) and 1.03 (P < 0005)] predicted mortality. A Receiver operating characteristic analysis showed that a cut-off value of InterV-del 100 ms (AUC = 0.86; P < 0001) predicted WHF and mortality with sensitivity and specificity of 75% and 90%; 81% and 84%, respectively.

CONCLUSIONS

TDE-derived interventricular asynchrony represents a prognostic indicator of major cardiac events at 2 years of follow-up in patients with LBBB but not advanced heart failure.

Effect of bundle branch block on microvolt T-wave alternans and electrophysiologic testing in patients with ischemic cardiomyopathy

BACKGROUND

T-wave alternans (TWA) and electrophysiology study (EPS) are used for risk stratification for sudden death.

OBJECTIVE

The purpose of the study was to determine the effect of bundle branch block or intraventricular conduction delay on TWA and EPS.

METHODS

386 patients with coronary artery disease, nonsustained ventricular tachycardia, and left ventricular ejection fraction < or =40% underwent TWA and EPS, and were followed for 40 +/- 19 months.

RESULTS

Patients with wide QRS were more likely than narrow QRS patients to have nonnegative TWA (77% vs 63%, P <.01) or positive EPS (60% vs 48%, P = .03). Nonnegative TWA predicted the combined endpoint of ventricular tachyarrhythmia or death in narrow QRS (HR = 1.64, P = .04) but not wide QRS patients (HR = 1.04, P = .91). Similarly, positive EPS predicted the combined endpoint in narrow QRS (HR = 2.28, P <.001) but not wide QRS patients (HR = 0.94, P = .84). In multivariate analysis, QRS width and TWA, as well as QRS width and EPS, were independent predictors of events. There was no TWA- or EPS-based difference in arrhythmia-free survival within any specific wide QRS morphology.

CONCLUSION

TWA and EPS are more often abnormal in patients with a wide QRS than in those with a narrow QRS. In patients with narrow QRS, both TWA and EPS stratify patients according to their risk of ventricular tachyarrhythmia or death. However, among patients with a wide QRS, regardless of specific QRS morphology, the risk is high and comparable regardless of TWA or EPS results. Therefore, the only truly low-risk group consists of those patients with negative test results and a narrow QRS.

Mortality in insureds with complete right or left bundle branch block

BACKGROUND

On May 1, 1954, a prospective mortality study was instituted in the Medical Department of the New England Mutual Life Insurance Company for all persons on whom an electrocardiogram (ECG) was made. Details were coded on an 80-column, mark-sense punched card for the ECG interpretation, for clinical findings, and for demographic/insurance data.

RESULTS

Mortality is based on the experience of 231 policy-holders with complete right bundle branch block (RBBB) and 45 policyholders with complete left bundle branch block (LBBB). These were drawn from 28,687 interpretation records 1954-1966, if there was some follow-up (FU) exposure between 1954 and 1975. Mortality data are for all ages and all durations combined. In cases with associated rated cardiovascular (CV) impairment, there were 22 observed vs 7.72 expected deaths in RBBB, and 6 observed vs 2.72 expected deaths in LBBB. Exposures and deaths were smaller when there was no rated CV impairment associated with the ECG abnormality: 11 observed vs 8.11 expected deaths in RBBB, and 3 observed vs 1.78 expected deaths in LBBB.

CONCLUSIONS

In complete RBBB, excess mortality was significant at the Poisson 95% confidence level when a rated CV impairment was associated with the RBBB, but the excess was minimal and not significant when the RBBB was essentially an isolated finding with no associated CV impairment. In LBBB the numbers of deaths were too few to permit even a 90% confidence level of significance when there was an associated CV impairment (the 2.72 expected deaths were just above the lower limit of 2.6 deaths at the 90% level).

Fascicular Conduction Disturbances After Coronary Artery Bypass Surgery: A Review With a Meta-Analysis of Their Long-term Significance

Fascicular conduction abnormalities are frequently reported following adult cardiac surgery, but their pathogenesis and long-term outcomes remain unclear. In this article, we review the epidemiological features, pathogenesis, diagnosis, and management, and the short-term and long-term significance of fascicular conduction abnormalities following coronary artery bypass graft (CABG) surgery, based on data from 30 studies. Conduction disturbances have an incidence of 3.4% to 55.8% after CABG surgery, the most common being right bundle branch block (RBBB). RBBB is usually transient and benign. Although a slew of factors have been implicated in the pathogenesis of fascicular conduction disturbances, the two most important factors are myocardial ischemia and type of cardioplegia. While a 12-lead electrocardiogram is the gold standard for diagnosis, additional tests such as myocardial enzymes or echocardiography may have additional diagnostic and prognostic value. Short-term prognosis after RBBB is good, but its impact on long-term survival is unclear. We conducted a meta-analysis, the first of its kind in this area, using long-term survival data from five studies. There was no difference in long-term survival between patients who developed conduction disturbances after CABG surgery, and those who did not, indicating a benign influence of conduction disturbances on long-term survival, and the lack of the necessity for monitoring or pacing. While the older literature reported an adverse impact of fascicular conduction disturbances on long-term survival, the more recent studies report a substantially reduced mortality after CABG surgery, despite a higher incidence of conduction disturbances, pointing to the effect of improved surgical techniques.

Noninvasive risk stratification of subjects with a Brugada-type electrocardiogram and no history of cardiac arrest

BACKGROUND

Recent studies suggest that the Brugada-type electrocardiogram (ECG) is much more prevalent than the manifest Brugada syndrome. Although invasive electrophysiologic investigations have been proposed as a risk stratifier, their value is controversial, and alternative noninvasive techniques may be preferred. We sought a noninvasive strategy to detect a high-risk group in a long-term follow-up study of subjects with a Brugada-type ECG, and no history of cardiac arrest.

METHODS

This study enrolled 124 consecutive subjects with a Brugada-type ECG. Prognostic indices included: age, sex, a family history of sudden death, syncopal episodes, a spontaneous coved-type ST-segment elevation, maximal magnitude of ST-segment elevation, a spontaneous change in ST segment, a mean QRS duration, maximal QT interval, QT dispersion, late potentials (LP) by signal-averaged ECG, and microvolt T-wave alternans.

RESULTS

Of the 124 subjects, 20 consenting subjects had an implantable defibrillator before follow-up. During a 40 +/- 19-month follow-up, 12 subjects (9.7%) reached one of the endpoints (sudden death or ventricular tachyarrhythmia). Of the 12 risk indices, a family history of sudden death, syncopal episodes, a spontaneous coved-type ST-segment elevation, a spontaneous change in ST segment, and LP had significant values. In multivariate analysis, a spontaneous change in ST segment had the most significance (a relative hazard, 9.2; P = 0.036). Combined assessment of this index and other significant indices obtained higher positive predictive values (43-71%).

CONCLUSIONS

A spontaneous change in ST segment is associated with the highest risk for subsequent events in subjects with a Brugada-type ECG. The presence of syncopal episodes, a history of familial sudden death, and/or LP may increase its value.

Risk factor implications of incidentally discovered uncomplicated bundle branch block

OBJECTIVE

To evaluate the long-term outcome of a community-based patient population with incidentally discovered asymptomatic and uncomplicated bundle branch block (BBB).

PATIENTS AND METHODS

A retrospective observational cohort study was undertaken of patients in Olmsted County, Minnesota, who were evaluated between 1975 and 1999 and were incidentally diagnosed as having BBB. We performed Kaplan-Meier analyses of all-cause mortality and development of first cardiac morbidity after the diagnosis of BBB, along with matched control group comparisons.

RESULTS

A total of 723 patients with left BBB (LBBB) (58.1%) and right BBB (41.9%) met criteria. Mortality was higher in patients with BBB compared with controls (absolute difference of approximately 10% over 20 years; hazard ratio = 1.27; confidence interval, 1.02-1.58; P=.03) as was the development of first cardiac-related morbidity (hazard ratio = 1.32; confidence interval, 1.14-1.54; P<.001). Patients with BBB and without the risk factors of diabetes, hypertension, and/or hypercholesterolemia showed increased long-term mortality compared with matched controls (no BBB) also without risk factors (P=.02). However, comparable mortality was shown between patients with BBB who did not have these risk factors and matched control patients who had these risk factors. The risk of developing cardiac-related morbidity also was increased in the presence of BBB, particularly LBBB.

CONCLUSIONS

Uncomplicated asymptomatic BBB (notably LBBB) with normal left ventricular ejection fraction is not benign. Our findings indicate that the presence of isolated BBB denotes a high-risk patient subgroup that has a compromised long-term outcome comparable to patients with conventional cardiovascular risk factors.

[Right bundle branch block: electrocardiographic and prognostic features]

The electrocardiographic appearances and the significance of right bundle branch block were described at the beginning of the 20th century. Typical appearances include prolongation > 0.12 s of the QRS complex, RR' or rR' or Rr' appearances in V1 and widened S waves in the leads exploring the left ventricle (SI, aVL, V5 and V6). A delay in the appearance of the intrinsic deflection > 0.08 s may also be observed in the right precordial leads and negative T waves with ST depression may be seen in V1 and sometimes in V2. Left axis deviation of the QRS complex greater than - 45 degrees suggests associated left anterior hemiblock. Right axis deviation beyond + 120 degrees is equivocal. The principal differential ECG diagnosis is the Brugada syndrome, a familial arrhythmogenic autosomal dominant cardiomyopathy of variable penetration. This diagnosis is suggested when ECG abnormalities are observed in patients with a personal or family history of sudden death. Right bundle branch block only seems to have haemodynamic consequences in cardiac failure with associated asynchrony of the left ventricle or in certain cases of right ventricular dilatation encountered in congenital heart disease. The prognosis of right bundle branch block in the absence of underlying cardiac disease is good but it may be poor in other cases, particularly coronary artery disease. Moreover, the prognosis of right bundle branch block to complete atrioventricular block is rare in the absence of associated cardiac disease.

Prognostic differences between different types of bundle branch block during the early phase of acute myocardial infarction: insights from the Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial

AIMS

Bundle branch block (BBB) early during acute myocardial infarction (AMI) is often considered high risk for mortality. Little is known about how different BBB types influence prognosis.

METHODS AND RESULTS

The HERO-2 trial recruited 17 073 patients with ischaemic symptoms lasting >30 min and either ST elevation with or without right bundle branch block (RBBB) or presumed-new left bundle branch block (LBBB). Electrocardiograms were performed before and 60 min after the start of fibrinolytic therapy. Using patients with normal intraventricular conduction as a reference, odds ratios (ORs) for 30-day mortality were calculated for different BBB types (LBBB, RBBB with anterior AMI, and RBBB with inferior AMI) present at randomization and/or 60 min, with adjustment for recruitment region, pre-infarction characteristics, time to randomization, hemodynamics, and Killip class. At randomization, the 873 patients (5.11%) with BBB had worse baseline characteristics than patients without BBB. In patients presenting with LBBB (n=300), the ORs for 30-day mortality were 1.90 (95% CI 1.39-2.59) before and 0.68 (0.48-0.99) after adjustment for other prognosticators. In patients presenting with RBBB (n=415) and anterior AMI, the ORs were 3.52 (2.82-4.38) before and 2.48 (1.93-3.19) after adjustment. In patients presenting with RBBB and inferior AMI (n=158), the ORs were 1.74 (1.06-2.86) before and 1.22 (0.71-2.08) after adjustment. Within 60 min, 143 patients (0.92%) developed new BBB. The adjusted ORs for 30-day mortality were 2.97 (1.16-7.57) in the 25 patients with new LBBB, 3.84 (2.38-6.22) in the 100 with new RBBB and anterior AMI, and 2.23 (0.54-9.21) in the 18 with new RBBB and inferior AMI.

CONCLUSION

RBBB accompanying anterior AMI at presentation and new BBB (including LBBB) early after fibrinolytic therapy are independent predictors of high 30-day mortality. These electrocardiographic features should be considered in risk stratification to identify high-risk patients.