Right Bundle Branch Block Group Research Articles

Association Between Right Bundle Branch Block and Ventricular Arrhythmia in Patients With Cardiac Sarcoidosis

BackgroundVentricular arrhythmia (VA) is a life-threatening condition associated with cardiac sarcoidosis (CS). Right bundle branch block (RBBB) is a common conduction disorder in CS; however, its association with VA remains unknown. ObjectivesThis study aimed to investigate the relationship between RBBB and VA in patients with CS. MethodsThis was a post hoc analysis of ILLUMINATE-CS (Illustration of the Management and Prognosis of Japanese Patients with Cardiac Sarcoidosis), a multicenter, retrospective, and observational study that evaluated the clinical characteristics and prognosis of CS. Eligible patients were divided into two groups based on the presence or absence of RBBB at the time of diagnosis. The primary outcome was serious ventricular arrhythmia events (SVAEs), defined as a combination of sudden cardiac death and documented ventricular fibrillation, sustained ventricular tachycardia, or appropriate implantable cardioverter-defibrillator therapy. ResultsOverall, 312 patients were studied, with 155 (49.7%) patients presenting with RBBB (RBBB group). Patients in the RBBB group had a higher prevalence of basal interventricular septum (IVS) thinning and prominent late gadolinium enhancement in the basal IVS on cardiac magnetic resonance imaging than those in the non-RBBB group. During a median follow-up of 3.0 years (IQR: 1.6-6.0 years), 66 patients experienced SVAE. In multivariable Cox regression analysis, the RBBB group was independently associated with a higher incidence of SVAEs (HR: 1.93 [95% CI: 1.14-3.28]; P = 0.015). ConclusionsIn patients with CS, RBBB was an independent predictor of SVAEs, which might reflect the specific scar distribution that is predominant in the IVS.

Ultra-high-frequency ECG volumetric and negative derivative epicardial ventricular electrical activation pattern

From precordial ECG leads, the conventional determination of the negative derivative of the QRS complex (ND-ECG) assesses epicardial activation. Recently we showed that ultra-high-frequency electrocardiography (UHF-ECG) determines the activation of a larger volume of the ventricular wall. We aimed to combine these two methods to investigate the potential of volumetric and epicardial ventricular activation assessment and thereby determine the transmural activation sequence. We retrospectively analyzed 390 ECG records divided into three groups-healthy subjects with normal ECG, left bundle branch block (LBBB), and right bundle branch block (RBBB) patients. Then we created UHF-ECG and ND-ECG-derived depolarization maps and computed interventricular electrical dyssynchrony. Characteristic spatio-temporal differences were found between the volumetric UHF-ECG activation patterns and epicardial ND-ECG in the Normal, LBBB, and RBBB groups, despite the overall high correlations between both methods. Interventricular electrical dyssynchrony values assessed by the ND-ECG were consistently larger than values computed by the UHF-ECG method. Noninvasively obtained UHF-ECG and ND-ECG analyses describe different ventricular dyssynchrony and the general course of ventricular depolarization. Combining both methods based on standard 12-lead ECG electrode positions allows for a more detailed analysis of volumetric and epicardial ventricular electrical activation, including the assessment of the depolarization wave direction propagation in ventricles.

Abstract 10034: Trends, Predictors, and Outcomes After Transcatheter Aortic Valve Implantation in Patients with Baseline Right Bundle Branch Block, from National Inpatient Sample

Introduction: Contemporary data on the outcomes after Transcatheter Aortic Valve Implantation (TAVI) in patients with a baseline right bundle branch block (RBBB) remains limited. Methods: We analyzed National Inpatient Sample (NIS) data from the year 2011 to 2018. Results: Of the patients who underwent TAVI, 3472 (1.6%) had baseline right bundle branch block and 212467 (98.4%) did not. The patients who had baseline RBBB were older at 83 years [Interquartile range (IQR), 77-87] vs 82 [75-87]) and had higher male gender representation (66.7 % vs 52.2%) (p<0.01 for all). Rates of permanent pacemaker implantation was significantly higher in the RBBB group compared to no RBBB group (30.5% vs 10.80%, p<0.01). Median Cost of care ($53206 vs $48429) and length of stay (5 vs 4 days) were considerably higher for patients with RBBB when compared to the comparison group (p<0.01 for all). Logistic regression analysis showed that age greater 75 [OR] 1.26 [95% CI 1.21-1.31], male sex [OR] 1.12 [95% CI 1.09-1.15] , atrial fibrillation [OR] 1.29 [95% CI 1.07-1.57], coronary artery disease [OR] 1.07 [95% CI 1.04-1.11] diabetes [OR] 1.07 [95% CI 1.02-1.12], hypertension [OR] 1.10 [95% CI 1.05-1.15] obesity [OR] 1.10 [95% CI 1.05- 1.1.16] and renal failure (OR, 1.12 [CI, 1.09-1.15] were significant predictors of PPM implantation post TAVI in patients with a RBBB at baseline. Conclusions: In conclusion we report that RBBB is associated with increased pacemaker implantation after TAVI. Factors like age greater than 75, male gender, coronary artery disease, diabetes, hypertension, obesity, and renal failure are associated with higher incidence of PPM implantation.

Adverse in-hospital prognosis in patients with non-ST-segment elevation myocardial infarction with right bundle branch block – red flag ECG and sicker patients

Abstract Introduction Recent recommendations regarding myocardial infarction (MI) underline the adverse prognosis associated with right bundle branch block (RBBB), suggesting that, in some cases of non-ST-segment elevation MI (NSTEMI) with RBBB a primary percutaneous coronary intervention (PCI) strategy should be considered. However, it is unclear if this is due to a more difficult and late diagnosis or to the clinical severity inherent to these patients (pts). Purposes To characterize the NSTEMI with RBBB population and find predictors of worse prognosis. Methods Retrospective analysis of pts included in the Portuguese Registry of Acute Coronary Syndromes with NSTEMI, comparing pts with RBBB (group A) vs without RBBB (group B), regarding clinical and demographic variables, diagnostic and therapeutic approaches. Primary endpoint was heart failure, electrical and mechanical complications and death in the in-hospital period. Results We included 9375 pts, 686 in group A and 8689 in group B. Pts in group A were more likely to be male (p<0.001) and over 75 years old (p<0.001). Also, they were more prone to have cardiovascular risk factors (hypertension - p<0.001, diabetes – p<0.001) and history of coronary artery disease (stable angina p=0.007, previous MI p=0.002 and revascularization, either PCI – p=0.016 or surgery – p<0.001), stroke (p<0.001), chronic kidney disease (p<0.001) and cancer (p=0.025), comparing to pts in group B. There were no differences between time from onset of symptoms and first medical contact or hospital admission between groups. Upon admission, these pts presented more frequently with hypotension (p=0.026), Killip class>II (p<0.001) and atrial fibrillation (p<0.001) than pts in group B. There were statiscally significant differences between groups, regarding the use of inotropes (p<0.001), non-invasive (p=0.008) and invasive ventilation (p=0.018) and temporary pacing (p=0.001), all of them higher in group A. Pts with RBBB were less likely to undergo coronary angiography (CA) (p<0.001). However, among those who did, there were no differences in CA timing (p=0.091), but pts from group A had more frequently multivessel disease (p=0.044) and no revascularization was undertaken (p=0.012). About 16.64% of all pts reached the endpoint, but unfavourable in-hospital outcome was significantly more common in group A (p<0.001). RBBB remained an independent predictor of the endpoint (p=0.032) in a multivariate regression analysis, controlled for other variables (namely gender, age, cardiovascular risk factors, previous evidence of cardiovascular disease, and clinical and coronary anatomy data) – AUC of 0.833. Conclusion Although pts with NSTEMI and RBBB have a poorer in-hospital prognosis, partly due to their bigger clinical complexity (older age, multiple comorbidities and complex coronary anatomy), RBBB itself still remains an independent predictor of worse outcome. Funding Acknowledgement Type of funding sources: None.

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

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

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

BackgroundRight bundle‐branch block (RBBB) and left bundle‐branch block (LBBB) play a role in the pathogenesis and progression of coronary artery disease (CAD). However, the clinical features and the severity of coronary artery disease associated with different subtypes of bundle‐branch block, according to time of new appearance, is not well characterized in patients with no known CAD.MethodsWe retrospectively analyzed data pertaining to consecutive patients with RBBB or LBBB who underwent coronary angiography. The severity of coronary lesions was evaluated using the SYNTAX score. The differential effect of new‐onset RBBB, old RBBB, new‐onset LBBB, and old LBBB on the severity of CAD and its association with clinical characteristics was quantified. Multivariate logistic regression analysis was performed to evaluate the effect of RBBB and LBBB on the degree of coronary atherosclerosis in patients without known CAD.ResultsOut of the 243 patients, 72 patients had old LBBB, 37 had new‐onset LBBB, 93 patients had old RBBB, and 41 patients had new‐onset RBBB. On univariate analysis, age, systolic blood pressure, diastolic blood pressure, creatinine, serum glucose, and glycosylated hemoglobin level were associated with high SYNTAX score (p < .05 for all). Patients in the new‐onset RBBB, old RBBB, new‐onset LBBB, and old LBBB groups showed significant differences in baseline characteristics and coronary atherosclerosis (p < .05 for all). However, there were no significant between‐group differences with respect to the degree of coronary atherosclerosis as assessed by SYNTAX score.ConclusionsNew‐onset RBBB, old RBBB, new‐onset LBBB, and old LBBB were not associated with the severity of coronary lesions as assessed by SYNTAX score in patients without known CAD.

Impact of Baseline Right Bundle Branch Block on Outcomes After Pulmonary Vein Isolation in Patients With Atrial Fibrillation

Right bundle branch block (RBBB) is one of the most frequent alterations of the electrocardiogram. Several studies have shown that RBBB is a risk factor of cardiovascular diseases. However, the clinical outcomes after pulmonary vein isolation (PVI) in patients with RBBB remain unclear. We enrolled consecutive atrial fibrillation (AF) patients who underwent PVI from the Osaka Rosai Atrial Fibrillation (ORAF) registry. We excluded patients with other wide QRS morphologies (left bundle branch block, ventricular pacing, and unclassified intraventricular conduction disturbances) and divided them into 2 groups: RBBB (QRS duration ≥120msec) and No-RBBB (QRS duration <120) groups. We compared the incidence of late recurrence of AF and/or atrial tachycardia (AT) (LRAF) between the 2 groups using a propensity score-matched analysis and evaluated the risk of LRAF using Cox regression model. We finally analyzed 671 consecutive AF patients. The RBBB group consisted of 50 patients (7.5%) and the No-RBBB group of 621 patients. Median follow-up duration was 734 [496, 1,049] days. Hypertension and diabetes mellitus were significantly higher in RBBB group than No-RBBB group. Among the 46 matched patients pairs, Kaplan-Meier analysis demonstrated that RBBB group had a significantly greater risk of LRAF than the No-RBBB group (p = 0.046). The Cox regression model revealed significantly higher risks of LRAF (HR, 2.30; 95% CI, 1.00 to 5.33;p=0.044) in RBBB group compared with No-RBBB group. Non-PV AF triggers were significantly higher in RBBB group than No-RBBB group (p = 0.048). In conclusion, RBBB can be an important predictor of LRAF after PVI.

Fusion pacing in patients with right bundle branch block who undergo cardiac resynchronization therapy

PurposePatients with right bundle branch block (RBBB) are less likely to respond to cardiac resynchronization therapy (CRT). We aimed to assess whether patients with RBBB respond to CRT with biventricular fusion pacing. MethodsConsecutive patients with RBBB at a single tertiary care center, who were implanted with a CRT device capable of biventricular fusion pacing using SyncAV programming, were assessed and compared to a historical cohort of CRT patients with RBBB. QRSd was measured and compared during intrinsic conduction, nominal CRT pacing and manual electrocardiogram-based optimized SyncAV programming. Left ventricular ejection fraction (LVEF) was also compared before and 6 months after CRT. ResultsWe included 8 consecutive patients with RBBB (group 1) who were able to undergo SyncAV programming and 16 patients with RBBB (group 2) from a historical cohort. In group 1, compared to mean intrinsic conduction QRSd (155 ± 13 ms), mean nominally-paced QRSd was 156 ± 15 ms (ΔQRSd 1.3 ± 11.6; p = 0.77) and SyncAV-optimized paced QRSd was 135 ± 14 ms (ΔQRSd −20.0 ± 20.4; p = 0.03 and ΔQRSd −21.3 ± 16.3; p = 0.008; compared to intrinsic conduction and nominal pacing respectively). In group 2, mean QRSd with nominal pacing was 160 ± 24 ms (ΔQRSd 3.8 ± 33.4; p = 0.66 compared to intrinsic conduction). In group 1, baseline LVEF was 22.1 ± 11.5 and after 6 months of follow-up was 27.8 ± 8.6 (p = 0.047). In group 2, the baseline LVEF was 27.2 ± 10.6 and after 6 months of follow-up was 25.0 ± 10.0 (p = 0.45). ConclusionsCRT programed to allow biventricular fusion pacing significantly improved electrical synchrony and LVEF in patients with RBBB. Larger studies are required to confirm these findings.

Cardiac resynchronisation therapy in patients with left bundle branch block with residual conduction.

AimTo evaluate whether left bundle branch block with residual conduction (rLBBB) is associated with worse outcomes after cardiac resynchronisation therapy (CRT).MethodsAll consecutive CRT implants at our institution between 2006 and 2013 were identified from our local device registry. Pre- and post-implant patient specific data were extracted from clinical records.ResultsA total of 690 CRT implants were identified during the study period. Prior to CRT, 52.2% of patients had true left bundle branch block (LBBB), 19.1% a pacing-induced LBBB (pLBBB), 11.2% a rLBBB, 0.8% a right bundle branch block (RBBB), and 16.5% had a nonspecific intraventricular conduction delay (IVCD) electrocardiogram pattern. Mean age at implant was 67.5 years (standard deviation [SD] = 10.6), mean left ventricular ejection fraction (LV EF) was 25.7% (SD = 7.9%), and mean QRS duration was 158.4 ms (SD = 32 ms). After CRT, QRS duration was significantly reduced in the LBBB (p < 0.001), pLBBB (p < 0.001), rLBBB (p < 0.001), RBBB (p = 0.04), and IVCD groups (p = 0.03). LV EF significantly improved in the LBBB (p < 0.001), rLBBB (p = 0.002), and pLBBB (p < 0.001) groups, but the RBBB and IVCD groups showed no improvement. There was no significant difference in mortality between the LBBB and rLBBB groups. LV EF post-CRT, chronic kidney disease, hyperkalaemia, hypernatremia, and age at implant were significant predictors of mortality.ConclusionCRT in patients with rLBBB results in improved LV EF and similar mortality rates to CRT patients with complete LBBB. Predictors of mortality post-CRT include post-CRT LV EF, presence of CKD, hyperkalaemia, hypernatremia, and older age at implant.

Clinical Impact of Preexisting Right Bundle Branch Block after Transcatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis.

Introduction Transcatheter aortic valve replacement (TAVR) is now the treatment of choice for patients with severe aortic stenosis regardless of their surgical risk. Right bundle branch block (RBBB) can be a predictor for development of significant atrioventricular (AV) block after TAVR, requiring permanent pacemaker implantation (PPI). However, data related to the risk of PPI requirement with preexisting RBBB is scarce. Hence, this systematic review and meta-analysis aims to assess clinical outcomes of patients undergoing TAVR with RBBB on preexisting electrocardiogram. Methods We performed a systematic literature review to identify randomized and nonrandomized clinical studies that reported any clinical impact of patients undergoing TAVR with preexisting RBBB. A total of eight databases including PubMed (Medline), Embase, Cochrane Library, ACP Journal Club, Scopus, DARE, and Ovid containing articles from January 2000 to May 2020 were analyzed. Results We identified and screened 224 potential eligible publications through the databases and found 14 relevant clinical trials for a total of 15,319 participants. There was an increased 30-day pacemaker implantation rate of 38.1% in the RBBB group compared to 11.4% in the no RBBB group with a risk ratio of 3.56 (RR 3.56 (95% CI 3.21–3.93, p < 0.01)). There was an increased 30-day all-cause mortality in the RBBB group of 9.5% compared with 6.3% in the no RBBB group with an odds ratio of 1.60 (OR 1.60 (95% CI 1.14–2.25, p < 0.01)). Conclusion This study indicates that patients with preexisting RBBB have higher incidence of PPI and all-cause mortality after TAVR compared with patients without RBBB. Further trials are needed to compare the clinical outcomes based on TAVR valve types and assess the benefit of PPI in patients with new-onset RBBB after TAVR.

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

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

Abstract 258: Mortality Comparison of Right Bundle Branch Block and Left Bundle Branch Block in US Veterans Undergoing Left Heart Catheterization - A Long Term Follow-up Study

Background: The prognostic importance of right bundle branch block (RBBB) has been debated. It has been described as a benign variant, especially when compared to left bundle branch block (LBBB). We studied the presence of bundle branch blocks in a high-risk U.S. Veteran cohort. Methods: Retrospective electrocardiogram (ECG) analysis for presence of RBBB or LBBB was conducted in 1,535 consecutive patients presenting for left heart catheterization. Evaluated risk factors were gender, age, BMI, hypertension, hyperlipidemia, diabetes, smoking history, chronic kidney disease, reduced ejection fraction and history of previous revascularization. Mean follow up time was 112 ± 66 months. Results: Analysis of 1,535 ECGs revealed 113 patients with RBBB and 65 patients with LBBB. Risk factor burden between the two groups appeared similar with exception of higher incidence of reduced ejection fraction and previous revascularization in the LBBB group. Mortality of RBBB group was 92.0% compared to 96.9% of LBBB group. Mean time to death for RBBB group was 74.1 months compared to 61.0 months for LBBB group. Hazard ratio (HR) for RBBB with Cox regression controlling for aforementioned risk factors was 1.41, 95% CI = 1.14-1.74; p =.002. HR for LBBB controlling for the same risk factors was 1.84, 95% CI = 1.42-2.40; p =&lt;.001. Conclusion: In a high-risk cohort of US Veterans, both LBBB and RBBB are independent risk factors for mortality. While LBBB is a known adverse risk factor, presence of RBBB portends a poor prognosis and warrants further research.

Electrical and mechanical dyssynchrony in patients with right bundle branch block

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

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

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

Conduction Abnormalities and Long-Term Mortality Following Septal Myectomy in Patients With Obstructive Hypertrophic Cardiomyopathy

BackgroundConduction abnormalities including bundle branch block are recognized sequelae following septal myectomy in patients with hypertrophic cardiomyopathy, but their incidence and effect on long-term mortality have not been well studied. ObjectivesThis study was conducted to determine the impact of conduction abnormalities on mortality in patients with obstructive hypertrophic cardiomyopathy following myectomy. MethodsThe outcomes of 2,482 patients with obstructive hypertrophic cardiomyopathy who underwent transaortic septal myectomy from 1961 to 2016 were analyzed. Pre-operative and early post-operative electrocardiograms were reviewed to determine conduction status. The study endpoint was all-cause mortality. ResultsMean age at operation was 54.2 ± 14.6 years, and 1,370 patients (55.2%) were men. Pre-operatively, 2,159 patients (87.0%) had normal conduction, of whom 38.8% developed left bundle branch block, 1.1% developed right bundle branch block (RBBB), and 0.6% had complete heart block (CHB) after myectomy. Among 112 patients with baseline RBBB, 34.8% developed CHB post-operatively. Overall, only 2.3% of patients developed CHB. Over a median follow-up period of 8.6 years, overall mortality differed among post-operative conduction groups after adjustment for age, sex, and concomitant procedures (p = 0.015). Specifically, mortality in those with paced rhythm after myectomy was significantly increased relative to those with normal conduction (hazard ratio: 1.57; 95% confidence interval: 1.15 to 2.14; p = 0.005), although no significant difference was observed in left bundle branch block and RBBB (vs. normal) groups. ConclusionsLeft bundle branch block is a common sequela after septal myectomy but does not influence post-operative mortality. Myectomy-related CHB is rare in patients with baseline normal conduction, while pre-existing RBBB greatly increases the risk for CHB. Persistent paced rhythm after operation is an independent predictor of mortality.

Association of Newly Developed Right Bundle Branch Block with Graft Rejection Following Heart Transplantation.

PurposeWe aimed to examine associations between right bundle branch block (RBBB) following heart transplantation (HT) and graft rejection.Materials and MethodsWe investigated 51 patients who underwent endomyocardial biopsies, electrocardiogram, right-side cardiac catheterization, and echocardiography at 1 month and 1 year after HT. We classified patients into four groups according to the development of RBBB, based on electrocardiogram at 1 month and 1 year: 1) sustained RBBB, 2) disappeared RBBB, 3) newly developed RBBB, and 4) sustained non-RBBB. The RBBB was defined as an RSR' pattern in V1 with a QRS duration ≥100 ms on electrocardiogram.ResultsThe newly developed RBBB group (n=13, 25.5%) had a higher rate of new onset graft rejection (from grade 0 to grade ≥1R, 30.8% vs. 10.0% vs. 21.4%, p=0.042) at 1 year, compared with sustained RBBB (n=10, 19.6%) and sustained non-RBBB group (n=28, 54.9%). In contrast, the incidence of resolved graft rejection (from grade ≥1R to grade 0) was higher in the sustained RBBB group than the newly developed RBBB and sustained non-RBBB groups (70.0% vs. 7.7% vs. 25.0%, p=0.042). Left atrial volume index was significantly higher in the newly developed RBBB group than the sustained RBBB and sustained non-RBBB groups (60.6±25.9 mL/m2 vs. 36.0±11.0 mL/m2 vs. 38.4±18.1 mL/m2, p=0.003).ConclusionClose monitoring for new development of RBBB at 1 year after HT, which was associated with a higher incidence of new onset graft rejection, may be helpful to identify high risk patients for graft rejection.

Prognostic Implication of Ventricular Conduction Disturbance Pattern in Hospitalized Patients with Acute Heart Failure Syndrome.

Background and ObjectivesConflicting data exist regarding the prognostic implication of ventricular conduction disturbance pattern in patients with heart failure (HF). This study investigated the prognostic impact of ventricular conduction pattern in hospitalized patients with acute HF.MethodsData from the Korean Acute Heart Failure registry were used. Patients were categorized into four groups: narrow QRS (<120 ms), right bundle branch block (RBBB), left bundle branch block (LBBB), and nonspecific intraventricular conduction delay (NICD). The NICD was defined as prolonged QRS (≥120 ms) without typical features of LBBB or RBBB. The primary endpoint was the composite of all-cause mortality or rehospitalization for HF aggravation within 1 year after discharge.ResultsThis study included 5,157 patients. The primary endpoint occurred in 39.7% of study population. The LBBB group showed the highest incidence of primary endpoint followed by NICD, RBBB, and narrow QRS groups (52.5% vs. 49.7% vs. 44.4% vs. 37.5%, p<0.001). In a multivariable Cox-proportional hazards regression analysis, LBBB and NICD were associated with 39% and 28% increased risk for primary endpoint (LBBB hazard ratio [HR], 1.392; 95% confidence interval [CI], 1.152–1.681; NICD HR, 1.278; 95% CI, 1.074–1.520) compared with narrow QRS group. The HR of RBBB for the primary endpoint was 1.103 (95% CI, 0.915–1.329).ConclusionsLBBB and NICD were independently associated with an increased risk of 1-year adverse event in hospitalized patients with HF, whereas the prognostic impacts of RBBB were limited.Trial RegistrationClinicalTrials.gov Identifier: NCT01389843

Patients with right bundle branch block and concomitant delayed left ventricular activation respond to cardiac resynchronization therapy.

Right bundle branch block (RBBB) typically presents with only delayed right ventricular activation. However, some patients with RBBB develop concomitant delayed left ventricular (LV) activation. Such patients may show a specific electrocardiographic (ECG) pattern resembling RBBB in the precordial leads in association with an insignificant S-wave in lateral limb leads (atypical RBBB). We therefore postulated that the ECG pattern of atypical RBBB might be able to identify a subgroup of patients likely to respond to cardiac resynchronization therapy (CRT). The purpose of this study was to assess the impact of RBBB ECG morphology on CRT response in patients with heart failure (HF). We evaluated the echocardiographic clinical response of 66 patients with RBBB treated with CRT and followed up for almost 2 years. The patients were divided electrocardiographically into 2 groups: 31 with typical RBBB and 35 with atypical RBBB. Responders were classified in terms of reduction in LV end-systolic volume index (ESVi) ≥ 15% or reduction in the New York Heart Association (NYHA) Class ≥ 1 or Packer score variation (NYHA response with no HF-related hospitalization events or death). The atypical RBBB group presented a longer LV activation time compared with the typical RBBB group (111.9 ± 17.6 vs. 73.2 ± 15.4 ms; P < 0.001). In the atypical and typical RBBB groups, respectively, 71.4% and 19.4% of patients were ESVi responders (P = 0.001) 74.3% and 32.3% were NYHA responders (P = 0.002); similarly, 71.4% and 29.0% of patients exhibited a 2-year Packer score of 0 (P = 0.002). Patients with atypical RBBB, which is a pattern highly suggestive of concomitant delayed LV conduction, may show a satisfactory response to CRT.

Clinical characteristics and value in early reperfusion therapy for new onset right bundle branch block in patients with acute myocardial infarction.

The value of the right bundle branch block (RBBB) in the treatment of acute myocardial infarction remains unclear. Studies on the RBBB may significantly influence the treatment of acute myocardial infarction. A total of 845 patients with acute myocardial infarction who underwent primary coronary angiography at Henan Provincial People's Hospital were analyzed. Higher peak enzyme levels, a higher ratio of Killip ≥II and closer proximal occlusion of infarct-related artery (IRA) were observed in patients with RBBB compared with those without. The ratio of TIMI flow 0/1 of IRA and ratio of received primary percutaneous coronary intervention (PCI) to IRA in the RBBB group were significantly higher compared with those in the left (L) BBB or no BBB groups. The in-hospital major adverse cardiac events (MACE) incidence in the RBBB group was higher compared with that in the no BBB group, but there was no significant difference between the RBBB and LBBB groups. Logistic regression revealed that proximal occlusion and TIMI flow 0/1 of IRA were predictive factors of RBBB. Cox regression analysis identified RBBB [risk ratio (RR), 4.682; P<0.001] and LBBB (RR, 3.687; P<0.001) as independent predictors of in-hospital MACE. The cumulative one-year survival rate in the RBBB group was significantly lower than those in the no BBB group (P<0.05) and the LBBB group (P<0.05). Similar to the guidelines regarding new onset of LBBB, new onset RBBB should be considered as a standard indicator for reperfusion therapy; as RBBB is associated with more severe symptoms, and higher incidents of complete occlusion of IRA and primary PCI treatment compared with LBBB.

Pre-Existing Right Bundle Branch BlockIncreases Risk for Death After Transcatheter Aortic Valve Replacement With a Balloon-Expandable Valve.

The aim of this study was to determine the impact of pre-existing right bundle branch block (RBBB) on clinical outcomes after transcatheter aortic valve replacement (TAVR). The impact of pre-existing RBBB on clinical outcomes after TAVR is unknown. Between October 2013 and August 2015, 749 patients undergoing TAVR using the Edwards SAPIEN XT prosthesis were prospectively enrolled in the OCEAN-TAVI (Optimized Transcatheter Valvular Intervention) registry from 8 Japanese centers. Electrocardiograms were obtained at baseline. After the procedure, follow-up outpatient visits or telephone interviews were conducted at 30 days, 6 months, and yearly. A total of 102 patients (13.6%) had pre-existing RBBB. The incidence of new pacemaker implantation was significantly higher in the RBBB group (17.6% vs. 2.9%; p< 0.01). The Kaplan-Meier analysis revealed that cardiovascular survival probability was significantly lower in the RBBB group than the no-RBBB group (log-rank p< 0.01). Patients with RBBB and without pacemakers were at higher risk for cardiovascular mortality in the early phase after discharge, and patients with RBBB and pacemakers had higher cardiovascular mortality at mid-term follow-up (log-rank p= 0.01). Amultivariate Cox regression model indicated that pre-existing RBBB (hazard ratio: 2.59; 95% confidence interval: 1.15 to 5.85; p< 0.01) was an independent predictor of cardiovascular mortality. Patients with RBBB demonstrated an increased risk for cardiovascular mortality after TAVR, and patients with RBBB and without pacemakers were at higher risk for cardiac death early after discharge. Patients withprior RBBB should be carefully monitored after undergoing TAVR.