Presence Of Right Bundle Branch Block Research Articles

Abstract 4136989: Association of alternating PR intervals with paroxysmal atrioventricular block in patients with right bundle branch block following cardiac surgery

Background: We previously observed a positive correlation between QRS duration and the preceding RP interval in sinus rhythm in certain patients experiencing new onset left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR). This unique phenomenon, termed inverse decremental conduction ( IDC ) or Yan conduction, prompted us to investigate whether IDC in the left bundle could manifest as AV conduction in an IDC pattern in patients with preexisting right bundle branch block (RBBB) and its association with atrioventricular block (AVB). Methods: 12 lead ECGs, available in-patient telemetry and mobile cardiac outpatient telemetry were reviewed in patients with sinus rhythm and preexisting RBBB who developed paroxysmal AVB requiring temporary or permanent pacemaker within 7 days following any types of cardiac surgery from 2014 to 2023 in Lankenau Medical Center. Results: A total of 9 patients (5 males) with a mean age of 71±15 years were identified to exhibit PR interval changes consistent with IDC prior to paroxysmal AVB. Among these patients, 6 had undergone TAVR, while the remaining 3 had undergone surgical aortic valve replacement, mitral valve repair, and ventricular septal defect repair, respectively. Specifically, PR interval alternation in the setting of RBBB occurred during sinus rhythm in a pattern that the longer RP interval is followed by a longer PR interval (Figure 1). This pattern exhibits the following features: 1) 8 of 9 patients had RBBB plus left anterior fascicular block (LAFB); 2) PR alternation occurred at sinus rates from 68 to 91 bpm within 5 days following surgical procedures; 3) proximal AVB occurred within 1 to 12 hours after PR interval alternation began. A positive correlation was established between PR and preceding RP interval in 2 of 9 patients whose telemetry data were available for analysis ( Figure 2A ). In a patient with RBBB who developed paroxysmal AVB without IDC changes in the PR interval post TAVR, intracardiac recording showed a decrease in AH interval but an increase in HV interval with slowing heart rates ( Figure 2B ), indicating that decremental conduction in AV node can mask IDC in Purkinje system. Conclusion: 1) PR alternation with longer PR following longer preceding RP interval in presence of RBBB, likely due to IDC in left bundle, heralds paroxysmal AVB; 2) PR interval changes resulting from IDC in left bundle in the setting of RBBB may be masked by decremental conduction in AV node.

Right bundle branch block in suspected acute coronary syndromes: Diagnostic challenges, treatment and prognosis

BackgroundThere is still conflicting evidence regarding the prognostic implications of right bundle branch block (RBBB) in the general population but also in patients with heart diseases like acute coronary syndromes (ACS). In accordance with current guidelines, RBBB in ACS patients is considered as STEMI equivalent. However, recent studies indicate that further differentiation is necessary in this group, as we will outline below. Methods and resultsA literature search was conducted in PubMed and Google Scholar.In previous studies, RBBB in the general population were mostly considered benign changes of the electrical conduction system. However, recent studies indicate that both complete and incomplete RBBB are associated with increased cardiovascular morbidity and mortality. In addition, among unselected patients with suspected ACS presenting to the emergency department, the prevalence of RBBB was 3 % and it was associated with elevated mortality. The subsequent angiographic identification of a culprit coronary artery stenosis leading to stent implantation was similar at approximately 2 % regardless of the initial ECG presentation with narrow QRS complexes, left bundle branch block (LBBB), or RBBB.Finally, in a group of high-risk patients for ST-elevation myocardial infarction (STEMI), the prevalence of RBBB was 12 %. While RBBB was associated with poor outcome compared to non-BBB and LBBB patients, diagnostic accuracy of STEMI criteria was not affected by the presence of RBBB. However, RBBB patients without distinct STEMI signs in ECG often showed acute STEMI on angiography indicating a potential benefit from immediate transfer to the cardiac catheterization laboratory. ConclusionIn the general population, patients with RBBB and risk factors may need further evaluation. Regarding ACS patients, recent studies support current guidelines that recommend acute invasive evaluation for high-risk ACS patients with RBBB, regardless of ST-T deviations. However, in an unselected group of ACS patients, differential diagnoses should also be investigated through additional diagnostic procedures.

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

BackgroundWhile left bundle branch block (LBBB) is a well-known risk feature in patients with acute myocardial infarction, and a rapid invasive management is recommended, data supporting this strategy for patients with right bundle branch block (RBBB) is less robust. MethodsIn total, 2139 patients with suspected ST-elevation myocardial infarction (STEMI) were triaged to acute coronary angiography based on a prehospital 12-lead electrocardiogram (ECG). Sensitivity and specificity for STEMI-ECG criteria were compared in RBBB and non-BBB patients. Adjusted hazard ratios for 1-year overall mortality were computed. ResultsSTEMI was adjudicated in 1832/2139 (85.6%) of all patients and in 102/117 (87.2%) of RBBB patients. ST-segment deviation followed typical ST-T patterns in most RBBB patients. Of 17 RBBB patients without significant ST changes, STEMI was adjudicated in 14 (82%). Diagnostic accuracy of STEMI criteria was comparable in RBBB and non-RBBB patients for inferior (sensitivity: 51.1% vs 59.1%, P = .14; specificity: 66.7% vs 52.1%, P = .33) and anterior STEMI (sensitivity: 35.2% vs 36.6%, P = .80; specificity: 58.3% vs 49.5%, P = .55). Diagnostic performance was lower for lateral STEMI in RBBB patients (sensitivity: 14.8% vs 4.4%, P = .001; specificity: 75.0% vs 98.4%, P < .001). Patients with RBBB had higher 1-year mortality compared with non-BBB patients (hazard ratio 2.3%; 95% confidence interval, 1.25-4.21. ConclusionECG criteria used for detection of STEMI showed comparable diagnostic accuracy in RBBB and non-BBB patients. However, STEMI was frequently present in RBBB patients not fulfilling diagnostic ECG criteria. RBBB patients showed poorer outcome after 1 year. Consequently, the presence of RBBB in suspected STEMI cases signifies a high-risk feature, aligning with established guidelines.

Cardiac MRI of characteristic motion findings in right bundle branch block.

While there have been many descriptions of characteristic motion findings in left bundle branch block (LBBB), there are few published descriptions of such findings in right bundle branch block (RBBB).The purpose of this study was to assess the frequency of particular regional motion findings in cardiac magnetic resonance imaging (CMR) studies of patients with RBBB, compared with normal subjects. We focused on three distinctive motion patterns that can be seen in RBBB during early systole: delayed apex-ward motion of the RV base, "reverse septal flash", and "basal bulge". The presence and relative magnitude of these findings were independently scored by four experienced observers, in 3-chamber and 4-chamber CMR cines, for both normal subjects and patients with RBBB. These motion patterns were found to be strongly associated with the presence of RBBB. While only moderately sensitive, they were quite specific for RBBB, when present. In particular, with ROC analysis, a combined feature set of the findings in the 4-chamber view had an area under the curve of 0.81.This previously undescribed set of RBBB-associated early-systolic regional motion features (delayed apex-ward motion of the RV base, "reverse septal flash", and "basal bulge") is strongly suggestive of RBBB when present, particularly in the 4-chamber view. Although here evaluated with CMR, it is also likely to be associated with RBBB when seen with other cardiac imaging modalities.

142 ADVANCED HEART FAILURE IN PATIENTS WITH ARRHYTHMOGENIC CARDIOMYOPATHY

Abstract Background Arrhythmogenic Cardiomyopathy (ACM) is a primary disease of the heart muscle, characterized by fibro-fatty myocardial replacement. Improvements in the clinical diagnosis and antiarrhythmic therapy, including the use of the defibrillator (ICD) and endo-epicardial catheter ablation, have increased the survival of these patients, who experience late complications such as advanced heart failure, which sometimes requires cardiac transplantation. Aim of the study To evaluate clinical, instrumental and genetic features of patients affected with ACM who developed heart failure (HF) and to sought for possible predictive factors of HF. Methods From the entire cohort of probands and family members followed at the Cardiomyopathy unit of our University (555 patients), 34 patients (29%), both probands (n= 26, 77%) and family members who experienced HF (6%) were selected (24 males, 71%). Their anamnestic, clinical, and instrumental data were compared with those without episodes of HF (n-HF). Results The mean age at diagnosis in HF cohort was 45.2 (±18) years. In 14 patients (41%) HF was the first symptom that led to diagnosis. According to 2010 TFC 30 patients (88%) had a definite diagnosis of ACM. The most frequently observed phenotype was the biventricular ACM (n=27, 79%). A disease-related genetic variant was found in 18 (53%) and DSP was the more common disease-gene, accounting for 24% of cases. The mean duration of follow-up was 12.6 (±11.0) years (min-max, 1-20 years). During this period a total of 14 subjects (41.2%) experienced life-threatening arrhythmias (LTA), while 13 patients (38.2%) died, of whom 11 (84.6%) because of refractory HF. Eighteen patients (53%) underwent cardiac transplantation (mean age 43±17 years), approximately 4 (±3.5) years after the onset of symptoms. Comparison with the n-HF cohort of ACM patients showed a significant difference on presence of T-wave inversion (TWI) in V1-V3 (p=0.001), TWI in V4-V6 (p=0.010), low QRS voltages both in precordial and limb leads (both p&amp;lt;0.001) and presence of left bundle-branch block and right bundle-branch block (both p&amp;lt;0.001). Regarding CMR, HF cohort was characterized by a significantly more dilated right and left ventricle EDV (both p&amp;lt;0.001), EF reduction (both p&amp;lt;0.001), presence of wall motion alterations (respectively, p=0.007 and p&amp;lt;0.001) and LGE (respectively, p=0.002 and p=0.005) compared to n-HF group. Regarding outcomes evaluation, the HF group showed more frequently LTA (HF=41.2% vs n-HF 21.5%, p=0.008). Finally, the presence of right bundle-branch block at ECG (OR=20.562, CI 1.884-224.413, p=0.013) and of impaired RV ejection fraction (OR=0.821, CI 0.719-0.937, p=0.004) were found to be independent predictors of HF. Conclusions Heart failure is a rare complication in patients affected with ACM, with a prevalence of 6% in our study. The mean age of onset of HF was 45.2 (±18) years. Furthermore, 18 patients (53%) had an unfavorable progression to heart transplantation. The presence of right bundle branch block at ECG and an impaired CMR RV-EF were found to be predictors of HF. Our results suggest the importance of scheduling a close follow-up in ACM patients who show initial signs and/or symptoms of HF, taking into consideration the fast rate of progression to refractory HF, once established.

681 RIGHT ARM PAIN WITH RIGHT BUNDLE BRANCH BLOCK: SHOULD WE PERFORM TROPONIN ASSAY?

Abstract We present the case report of a 67 year old man with no previous cardiovascular history, who was admitted to our emergency department (ED) for two days onset of right arm pain which was not responsive to painkillers. On admission, he was asymptomatic for typical angina. His BP was 190/100 mmHg, HR 80 bpm, SpO2 99% and apyretic. The clinical examination was unremarkable. The ECG showed sinus rhythm, complete right-bundle-branch-block (RBBB) and left-axis deviation, negative T-waves in V1-V2 and positive T-waves in V3 &amp;gt; V6 (figure 1A) (no previous ECGs were available). The blood samples showed normal renal function and blood count. Surprisingly, there was a progressive rise in troponin I levels 0.023 &amp;gt; 0.061 &amp;gt; 0.38 ng/ml (ULN 0.010 ng/ml). Echocardiography revealed preserved LVEF without major regional wall motion abnormalities (RWMA), nor any valvulopathy. Despite the atypical presentation and ECG, the troponin rise was strongly suggestive for an acute coronary syndrome (ACS), so the patient was sent to the Cath lab to undergo coronary angiography (CAG). At the time of the CAG he was asymptomatic. The exam revealed thrombotic occlusion of mid-segment left anterior descending artery (LAD). Primary PCI with DES implantation was performed obtaining TIMI 3 flow (figure2). The remaining hospital stay was uneventful, the patient was discharged asymptomatic after 4 days. Pre-discharge echocardiography reported normal LVEF with no RWMA. Discharge ECG showed persistency of the RBBB with negative T-waves from V1 to V4 (figure 1B). On 3 months follow up visit the patient is asymptomatic with preserved LVEF. On ECG there is persistency of RBBB and normalization of the T-waves in the precordial leads (figure 1C). Discussion This case report is an atypical presentation of acute thrombotic occlusion of an epicardial coronary artery, without the typical ST segment elevation (STEMI equivalent) and without the typical angina. RBBB may represent an uncommon ECG presentation of acute myocardial ischemia, with an incidence from 2 to 6% overall, with TIMI 0 flow in the infarct-related artery only in half of the cases. RBBB (especially new or presumably new onset RBBB) is also associated with increased mortality and morbidity, possibly due to delay in diagnosis and primary reperfusion strategies. Troponin dosage was fundamental to understand that we were facing an acute coronary syndrome, however we were not expecting complete occlusion of the LAD. In conclusion, the presence of RBBB on admission may delay primary reperfusion strategies, especially when symptoms are atypical. However, in case of unresponsive pain and presumably new-onset conduction disturbances on ECG it is mandatory to perform troponin assay and therefore drive the correct timing of coronary revascularization.

Abstract 11282: Artificial Intelligence Derived Algorithm to Screen for Ebstein’s Anomaly of the Tricuspid Valve Utilizing Echocardiography

Introduction: Ebstein’s anomaly (EA) is a rare congenital anomaly of the tricuspid valve associated with heart failure and arrhythmias. Currently available imaging modalities like transthoracic echocardiography, cardiac magnetic resonance imaging (MRI), or computerized tomography (CT) are not viable for screening large asymptomatic populations. Hypothesis: A deep learning algorithm, implemented using a convolutional neural network (CNN) applied to the standard 12-lead ECG can be used as an accurate screening tool for EA in children and adults. Method: We identified 1,154 EA patients and 21,430 age- and sex-matched controls (1:20 ratio) between 1987 - 2020. A CNN was trained, validated and tested using digital 12-lead ECGs in 70%, 10% and 20% of the cohort respectively, divided by random shuffling. Results: The mean age was 26.68±19.23 years (41.8% aged &lt; 18 years, 56.41% female) for the EA cohort and 28.36±18.65 years (37.2% aged &lt;18 years, 55.67% female) for the control cohort. Following training and validation the area under the curve (AUC) for detecting EA in the testing cohort was 0.976 (95% CI 0.962 - 0.989) with prediction accuracy of 0.959. In subgroup analysis, the AUC was comparable in males (0.970, 95% CI 0.946-0.995) and females (0.979, 95% CI 0.964-0.994), those &lt;18 (0.980, 95% CI 0.958-1.000) and ≥18 years old (0.972, 95% CI 0.954-0.989), as well as in those with right bundle branch block (RBBB) (0.969, 95% CI 0.950-0.989) and without RBBB (0.950, 95% CI 0.922-0.978) on ECG. Conclusion: Artificial intelligence enhanced ECG based detection of EA is possible with high diagnostic accuracy. Following further refinement and external validation, this algorithm can facilitate early detection of EA using ECGs, a widely available and inexpensive tool. Figure: Receiver operating characteristic (ROC) curve for the performance of the artificial intelligence CNN in detecting EA in the test cohort stratified by (A) age (&lt; 18 and ≥ 18 years) and sex and (B) presence of RBBB.

Abstract 10530: Incidence and Electrocardiographic Predictors of Atrioventricular Conduction Recovery After Permanent Pacemaker Implantation in Transcatheter Aortic Valve Replacement

Background: High grade atrioventricular (AV) block (HGAVB) after transcatheter aortic valve replacement (TAVR) requiring permanent pacemaker implantation (PPM) is a well-established complication, but recovery of intrinsic AV conduction is not well studied. We assessed the incidence and electrocardiography (ECG) predictors of AV conduction recovery after PPM implantation post-TAVR. Methods: In this multicenter, retrospective study, consecutive patients undergoing TAVR between January 2015 to February 2019 were identified. All patients requiring PPM for HGAVB within 30 days after TAVR were included. Follow up ECGs, PPM checks, and clinic notes were reviewed to determine AV conduction recovery, defined as no need for ventricular pacing. Results: There were 533 TAVR patients, 443 with balloon expandable valves (BEV) and 90 with self-expanding valves (SEV). 5.1% of patients (n=27) required PPM for HGAVB, including 4.5% (n=20) from BEV group and 7.8% (n=7) from SEV group. Right bundle branch block (RBBB) was the most common baseline ECG finding (n=19). Mean time to PPM implant was 3.3±4.5 days. 11 patients received leadless and 16 received conventional pacemakers. At 6 months, 65% (n=13) of BEV group and none of SEV group had AV conduction recovery. BEV patients without AV conduction recovery had significantly longer baseline PR intervals compared to those with recovery (248±85 msec vs 169±22 msec; 95% CI 12.5-147.2; p=0.024). There were no significant differences in baseline QRS duration or presence of RBBB between those with and without AV conduction recovery. Conclusion: AV conduction recovery is more frequent after PPM implantation in TAVR patients receiving BEV (65%) compared to SEV (0%). Normal baseline PR intervals at baseline is associated with higher rate of AV conduction recovery among BEV patients. Temporary pacing with leadless pacemakers may be an alternative to conventional pacemakers in BEV patients without baseline first degree AV block.

Value of a 12-Lead Electrocardiogram for Assessing P Waves.

Scenario: The rhythm strip below was printed from the bedside monitor of a 71-year-old man admitted to the intensive care unit for hypoxemic respiratory failure, fluid overload, and septic shock. The patient’s history includes coronary artery disease, hypertension, diabetes, paroxysmal atrial fibrillation after successful cardioversion (prescribed at-home apixaban), alcoholic cirrhosis, heart failure (ejection fraction, 50%), and chronic obstructive pulmonary disease (COPD). When this electrocardiogram (ECG) was generated, his blood pressure was 119/63 mm Hg, heart rate was 95/min, and oxygen saturation was 97% while receiving mechanical ventilation with a fraction of inspired oxygen of 0.8. The nurse noted that the rhythm looked like either a heart block or multifocal atrial tachycardia (MAT) and decided to record a 12-lead ECG (see next page). What is your interpretation?Atrial flutter (AFL) with 3:1 conduction with a ventricular rate of ~100/min and right bundle branch block (RBBB).Atrial flutter is common in patients with hypertension, diabetes, COPD, alcohol misuse, and atrial fibrillation (risk factors in this scenario) and is typically initiated or terminated by a premature complex (atrial or ventricular) or rapid atrial pacing. When a premature stimulus excites an area in the atrium, it travels in a single stable reentry circuit (either clockwise or counterclockwise) that is long enough to allow initially depolarized myocardial tissue to recover and then be capable of depolarizing again owing to the reentered stimulus. This mechanism can be seen in this example, particularly in leads III and aVF, as regular, uniform flutter waves (or F waves). The typical atrial rate for AFL is 200-350/min and is characterized by the absence of an atrial diastolic interval, as is seen in sinus rhythm.The rhythm strip displayed only leads II and V1 and showed upright P waves in V1 with various PR intervals, which could be confused with third-degree heart block. In lead II, the P wave is negative, suggesting a junctional rhythm with retrograde conduction of the atria. However, the sharp negative P wave in lead II raises the suspicion of AFL, which was confirmed on the 12-lead ECG. The unique feature of F waves (ie, “sawtooth” pattern) associated with AFL can be seen clearly in leads III and aVF. The F waves that are negative in the inferior leads but positive in V1 indicate the AFL is moving in a counterclockwise direction, which is most common (~75% of cases). The flutter waves should not be confused with MAT, which typically exhibits at least 3 different P-wave morphologies and is irregular because of multiple focal sites of atrial impulse formation. In contrast, AFL is a self-sustaining macroreentrant atrial arrhythmia without focal sites of impulse formation. The ventricular rate in AFL is usually a multiple of the FF interval. In this case, the F waves occur at a rate of 300/min and result in a ventricular rate of ~100/min and can be slightly irregular.Left ventricular hypertrophy in the presence of RBBB can be examined by using an S wave >2 mm in V1 or an R wave >15 mm in V5 or V6, both of which are absent on this ECG.Clinical management is focused on converting AFL to normal sinus rhythm, which will reduce the heart rate and prevent embolic stroke. In this case, the cardiology service was consulted, and ibutilide, an antiarrhythmic, was prescribed with a return to normal sinus rhythm. The patient’s anticoagulant was changed to clopidogrel, an antiplatelet. Given this patient’s underlying risk factors and the risk of prolonging QT with ibutilide, the QT interval should be closely monitored to prevent torsades de pointes. The patient's hospital course was complicated by continued respiratory distress and acute alcohol withdrawal. He was later transferred to the step-down unit.

Estimation of the QTc interval in the presence of right bundle branch block: A comparative study using validated formulae for left bundle branch block

BackgroundAdequate measurement of the QT interval is of clinical importance in order to identify patients at higher risk for ventricular arrhythmias. Previous studies have described different methods to estimate baseline QT in patients with left bundle branch block (LBBB). However, the evidence regarding the assessment of the QT in patients with right bundle branch block (RBBB) is scarce. AimTo analyze the feasibility and reliability of the different formulae described for LBBB in the estimation of the baseline QT in the presence of RBBB. MethodsWe performed an observational study including patients who underwent electrophysiology study and/or ablation. Two types of RBBB were considered: 1) pacing-induced and 2) transient true RBBB. QRS, JT and QT intervals were measured during baseline and RBBB. Estimated QTc was calculated using LBBB formulae: Bogossian, Rautaharju, Tabatabaei, Tang-Rabkin, Yankelson, Wang. Linear correlation and intraclass correlation coefficients (ICC) were used to assess the reliability of these formulae for the estimation of baseline QTc. ResultsWe finally included a total of 100 patients. Correlations between baseline and estimated QTc were strong (R > 0.7) for all the formulae except for Tabatabaei. Yankelson and Wang showed the highest reliability (ICC = 0.775 and 0.727, respectively). Yankelson appeared to be the most accurate formula, with a mean estimated QTc closest to baseline values. ConclusionPreviously described formulae for LBBB exhibited marked differences regarding reliability in the estimation of the QTc interval in the presence of RBBB. According to our results, Yankelson showed the most consistent and accurate agreement in this setting.

Value of Electrocardiography to Distinguish Fabry Disease from Sarcomeric Hypertrophic Cardiomyopathy

Fabry disease (FD) is a rare genetic disorder that leads to left ventricular hypertrophy (LVH), frequently misdiagnosed as hypertrophic cardiomyopathy (HCM). We sought to assess the value of electrocardiography for distinguishing FD from HCM. We retrospectively reviewed and compared standard electrocardiograms and echocardiograms from 26 patients with FD and LVH and 33 sarcomeric patients with HCM, matched for gender, age, and degree of LVH. The mean age of patients with FD was 46years (interquartile range) (28 to 53) and of HCM 50 (30 to 61) years (p=0.27). Of them, 16 (61%) and 25 (76%) were male, respectively (p=0.26). Indexed left ventricular mass was 166g/m² in FD versus 181g/m² in HCM (p=0.88). All patients with FD and 30 (91%) with HCM were in sinus rhythm (p=0.25). A higher prevalence of right bundle branch block (RBBB) was observed in FD (27%) versus HCM (6%) (p=0.03). The PR interval was shorter in FD, 140ms (120-160) versus 160ms (140 to 180) (p=0.004). P-wave duration was longer in patients with FD, 100ms (80 to 120) versus 80ms (80 to 100) (p=0.01). The PQ interval (PR interval minus P-wave duration) was shorter in patients with FD, 40ms (20 to 45) versus 80ms (40 to 80) (p=0.001). There were no differences regarding P-wave amplitude, QRS complex duration, corrected QT length, conduction or repolarization abnormalities, Sokolow-Lyon index, and Cornell index. After multivariate adjustments for RBBB, PR interval, P-wave duration, and PQ interval, a PQ interval ≤40ms and RBBB were significantly associated with FD. In conclusion, there are electrocardiogram characteristics, such as the presence of RBBB or a PQ interval ≤40ms, that may be helpful for screening and reducing the delay in FD diagnosis.

Prevalence and impact on prognosis of right-bundle branch block in patients with acute heart failure: Findings from the RICA registry

ObjectivesThis work aims to determine the prevalence, characteristics, and impact on prognosis of right bundle branch block (RBBB) in a cohort of acute heart failure (AHF) patients. MethodsWe prospectively analyzed 3,638 AHF patients included in the RICA registry (National Heart Failure Registry of the Spanish Internal Medicine Society). We independently analyzed the relationship between baseline and clinical characteristics and the presence of RBBB as well as the potential impact of RBBB on 1-year all-cause mortality and a composite endpoint of 90-day post-discharge hospitalization or death. ResultsThe prevalence of RBBB was 10.9%. Patients with RBBB were older, a higher proportion were male, had more pulmonary comorbidities, had higher left ventricular ejection fraction values, and had worse functional status. There were no differences in risk for patients with RBBB, with an adjusted hazard ratio (95% confidence interval) for 1-year mortality of 1.05 (0.83–1.32), and for the composite endpoint of 90-day post-discharge hospitalization or death of 0.97 (0.74–1.25). These results were consistent on the sensitivity analyses. ConclusionsFew patients with AHF present with RBBB, which is consistently associated with advanced age, male sex, pulmonary comorbidities, preserved left ventricular ejection fraction, and worse functional status. Nonetheless, after considering these factors, RBBB in AHF patients is not associated with worse outcomes.

Prevalencia e impacto en el pronóstico del bloqueo de rama derecha en pacientes con insuficiencia cardíaca aguda: hallazgos del registro RICA

ObjectivesThis work aims to determine the prevalence, characteristics, and impact on prognosis of right bundle branch block (RBBB) in a cohort of acute heart failure (AHF) patients. MethodsWe prospectively analyzed 3,638 AHF patients included in the RICA registry (National Heart Failure Registry of the Spanish Internal Medicine Society). We independently analyzed the relationship between baseline and clinical characteristics and the presence of RBBB as well as the potential impact of RBBB on 1-year all-cause mortality and a composite endpoint of 90-day post-discharge hospitalization or death. ResultsThe prevalence of RBBB was 10.9%. Patients with RBBB were older, a higher proportion were male, had more pulmonary comorbidities, had higher left ventricular ejection fraction values, and had worse functional status. There were no differences in risk for patients with RBBB, with an adjusted hazard ratio (95% confidence interval) for 1-year mortality of 1.05 (0.83-1.32), and for the composite endpoint of 90-day post-discharge hospitalization or death of 0.97 (0.74-1.25). These results were consistent on the sensitivity analyses. ConclusionsFew patients with AHF present with RBBB, which is consistently associated with advanced age, male sex, pulmonary comorbidities, preserved left ventricular ejection fraction, and worse functional status. Nonetheless, after considering these factors, RBBB in AHF patients is not associated with worse outcomes.

Incidence and in-hospital outcomes of right bundle branch block in patients with ST elevation myocardial infarction undergoing primary angioplasty

The presence of right bundle branch block (RBBB) in patients with ST elevation myocardial infarction (STEMI) has been associated with poor outcomes. However, the clinical and angiographic impact of RBBB in patients undergoing primary angioplasty are poorly established. This study aimed to evaulate the incidence, clinical and angiographic impact of RBBB in patients with STEMI treated with primary percutaneous coronary intervention (PCI). We included 352 patients admitted for STEMI and managed with primary PCI. They were enrolled between January 2000 and March 2017 in Cardiology B department of Fattouma Bourguiba university hospital. The presence of RBBB was made by a systematic electrocardiogram at admission. Right bundle branch block was documented in 12 patients (3.4%). Patients with RBBB were older (Mean age = 68.3 ± 13.35 years versus 59.7 ± 11.4 years, P = 0.012). There was not difference between male and female. Diabetes and history of angina were significantly higher in patients with RBBB ( P < 0.001 for both). These patients presented more frequently anterior STEMI, congestive heart failure, cardiogenic shock at admission ( P < 0.001 for all) and ventricular arrythmias ( P = 0.029). On coronarography, RBBB patients had higher incidence of multivessel disease ( P = 0.032), initial TIMI flow ≤ 1 ( P = 0.024) and no-reflow after PCI ( P = 0.014). All cause in-hospital mortality was greater in patients with RBBB (25% vs. 11.7%, P < 0.001). On multivariate analysis, persistant RBBB emerged as an independent predictor of in-hospital death (Odd ratio= 1.6; CI = 95%: 1.12–3.43; P < 0.001). Although RBBB presents in only about 3.5% of patients with STEMI, it was associated with poor in-hospital prognosis and increased in-hospital mortality.

Epicardial fat volume is associated with preexisting atrioventricular conduction abnormalities and increased pacemaker implantation rate in patients undergoing transcatheter aortic valve implantation

Epicardial fat tissue (EFT) is a highly metabolically active fat depot surrounding the heart and coronary arteries that is related to early atherosclerosis and adverse cardiac events. We aimed to investigate the relationship between the amount of EFT and preexisting cardiac conduction abnormalities (CCAs) and the need for new postinterventional pacemaker in patients with severe aortic stenosis planned for transcatheter aortic valve implantation (TAVI). A total of 560 consecutive patients (54% female) scheduled for TAVI were included in this retrospective study. EFT volume was measured via a fully automated artificial intelligence software (QFAT) using computed tomography (CT) performed before TAVI. Baseline CCAs [first-degree atrioventricular (AV) block, right bundle branch block (RBBB), and left bundle branch block (LBBB)] were diagnosed according to 12-lead ECG before TAVI. Aortic valve calcification was determined by the Agatston score assessed in the pre-TAVI CT. The median EFT volume was 129.5 ml [IQR 94–170]. Baseline first-degree AV block was present in 17%, RBBB in 10.4%, and LBBB in 10.2% of the overall cohort. In adjusted logistic regression analysis, higher EFT volume was associated with first-degree AV block (OR 1.006 [95% CI 1.002–1.010]; p = 0.006) and the need for new pacemaker implantation after TAVI (OR 1.005 [95% CI 1.0–1.01]; p = 0.035) but not with the presence of RBBB or LBBB. EFT volume did not correlate with the Agatston score of the aortic valve. Greater EFT volume is associated independently with preexisting first-degree AV block and new pacemaker implantation in patients undergoing TAVI. It may play a causative role in degenerative processes and the susceptibility of the AV conduction system.

Comparing predictors of permanent pacemaker insertion after TAVR in new-generation versus early generation heart valves

Abstract Introduction Transcatheter Aortic Valve Replacement (TAVR) has emerged as the standard of care for patient with severe aortic stenosis. Conduction abnormalities leading to permanent pacemaker (PPM) implantation is one of the most common complication after TAVR. Newer generation valves (NGV) such as Sapien S3, XT and Evolut are widely being used in real time practice. The aim of this analysis is to compare the predictors associated with increased risk of PPM implantation after TAVR in newer generation valves (NGV) as compared to older generation valves (OGV). Methods A comprehensive literature search was performed in PubMed, Embase, and Cochrane to identify relevant trials. Summary effects were calculated using a DerSimonian and Laird random-effects model as odds ratio with 95% confidence intervals for all the clinical endpoints. Results 18 observational studies with 16,004 patients were identified. The incidence of PPM implantation after TAVR in our analysis was 8.9%. For the NGV, right bundle branch block (RBBB) and atrioventricular (AV) block were independent predictors of PPM insertion after TAVR. Baseline heart rate, presence of atrial fibrillation, and baseline intraventricular conduction delay were not significant predictors. However, for the OGV, risk of PPM implantation after TAVR was higher in presence of RBBB, depth of implant, valve size/annulus size, presence of atrial fibrillation and post-procedure AV block. Conclusions Our analysis identified 2 factors that were significantly associated with increased risk of PPM insertion after TAVR in NGV compared to 6 factors with OGV. With the increasing physician expertise with TAVI and use of NGV, the incidence of post TAVR PPM insertion has reduced but baseline RBBB and AV conduction block still continue to be significant predictors of increased PPM insertion after TAVR. Funding Acknowledgement Type of funding sources: None.

How to Estimate QT Interval in Patients With Left or Right Bundle Branch Block: A Systematic Review.

Prolonged QT interval related to psychopharmacological treatment is a risk factor for potentially life-threatening arrhythmias. Electrocardiographic measurements are recommended in patients with cardiovascular risk factors before initiating treatment with potentially QT-prolonging medications, such as certain antidepressants or antipsychotics. In patients with left bundle branch block (LBBB) or right bundle branch block (RBBB), conventional QT-estimation methods will lead to overestimation of the QT interval, as the conduction defect, reflected by the QRS duration, will increase the QT interval without representing longer repolarization as in drug-induced QT prolongation. We conducted a systematic review of methods to estimate QT interval in the presence of LBBB or RBBB. We searched electronic databases Embase and Medline (last search, August 12, 2020). We found 8 different methods, including linear correction formulae with and without correction for heart rate, or simpler formula correcting QRS duration with empirically derived modifiers. Only 3 of 8 methods were applicable in the presence of RBBB, whereas all 8 methods could be applied in the presence of LBBB. The QT interval is overestimated in patients with LBBB or RBBB, when using conventional measurements. Several alternative correction formulae exist, which can be applied using standard measurements from ordinary electrocardiographic readings. However, it is currently unknown whether or not the QT prolongation observed in the presence of bundle branch block significantly increases the risk of arrhythmias, as these formulae have not been tested against patient-specific clinical outcomes.

Abstract 16388: Feature Selection Using Recursive Feature Elimination (RFE): Machine Learning Application in Predicting Permanent Pacemaker Implantation (PPMI) in Patients Undergoing Transcatheter Aortic Valve Replacement (TAVR)

Introduction: TAVR is increasingly being performed because of several recent large-scale clinical trials supporting its use across a range of patient sub-classes. Although it provides life-altering relief of severe aortic stenosis, adverse outcomes are not uncommon including paravalvular leak, life-threatening bleeding, acute kidney injury, stroke, and PPMI. RFE can help certain classification models like logistic regression in better predicting binary variables such as PPMI by creating a model based upon a set of predictors and then progressively eliminating variables to optimize the model. Objective: To determine whether RFE when applied to logistic regression would result in discriminatory ability in the prediction of PPM implantation in patients undergoing TAVR Methods: Pre- and postoperative data from a single institution were collected for all patients undergoing TAVR without a history of PPMI between January 2016 and December 2019. EKG data obtained included QRS duration, presence of atrioventricular block, left anterior and posterior fasicular block and right bundle branch block(RBBB). Data was imported into Python and a stratified 5 fold cross validation with SMOTE oversampling was run with RFE running at every fold to avoid overfitting. Upon completion, a rank score was tabulated for each predictor and a final logistic regression model with the highest optimized receiver under the operator curve was exported and applied to a test set. The receiver under the operator score was calculated for the training and test sets and the variables of importance were identified using RFE. Results: The total sample size for this cohort was 513 patients, with a PPMI incidence of 8.58%. The training set consisted of 40 variables and 384 patients, and the test set had 129 patients. The final optimized model on the training set had an ROC of 0.75 and utilized three features out of forty. The three features identified by RFE were: implanted TAVR valve size, QRS duration, and presence of RBBB. The model had a ROC of 0.63 on the test set. Conclusions: Our results show that presence of pre-op RBBB, prolonged QRS duration and valve size were risk factors for PPMI. Logistic regression classification had modest ability in predicting the need for PPMI after TAVR.

Intraventricular conduction defects in patients with st-segment elevation myocardial infarction – the paradox of right bundle branch block

Abstract Intraventricular conduction defects (IVCD) in patients with acute myocardial infarct (AMI) are predictors of a worse prognosis. When acquired they can be the result of an extensive myocardial damage. Purpose To assess the impact of IVCD, regardless of being previously known or presumed new, on in-hospital outcomes of patients with AMI with ST segment elevation (STEMI) or undetermined location. Methods From a series of patients included in the National Registry of Acute Coronary Syndrome between 10/1/2010 and 9/1/2019, were selected patients with STEMI or undetermined AMI, undergoing coronary angiography. Results 7805 patients were included: 461 (5.9%) presenting left bundle branch block (LBBB), 374 (4.8%) with right bundle branch block (RBBB) and 6970 (89.3%) with no IVCD. Clinical characteristics as well as in-hospital outcomes are described in the table 1. An unexpected worse prognosis in patients with RBBB has motivated a multivariate analysis. RBBB remained an independent predictor of in-hospital mortality (OR 1.91, 95% CI 1.04–3.50, p=0.038), along with female gender (OR 1.73, 95% CI 1.11–2.68, p=0.015), Killip Class&amp;gt;1 (OR 2.26, 95% CI 1.45–3.53, p&amp;lt;0.001), left ventricular ejection fraction &amp;lt;50% (OR 3.93, 95% CI 2.19–7.05, p&amp;lt;0.001) and left anterior descending artery as the culprit lesion (OR 1.85, 95% CI 1.16–2.91, p=0.009). Conclusion In spite of an apparent better clinical profile, in the current large series of unselected STEMI patients, the presence of RBBB is associated with the worst in-hospital outcome. RBBB doubles the risk of death, being an independent predictor of in-hospital mortality. Funding Acknowledgement Type of funding source: None

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.