Left Bundle Branch Block Morphology Research Articles

A patient with obstructive hypertrophic cardiomyopathy: a case report

Background: Hypertrophic cardiomyopathy (HCM) is a left ventricle hypertrophic condition related to genetic disorders involving the gene encoding protein from the cardiac sarcomere apparatus. The prevalence of this disease is relatively low, but various clinical presentations make underrecognized and underdiagnosed. We reported obstructive hypertrophy cardiomyopathy patients with an episode of unexplained syncope and malignant arrhythmia.Case Report: A 44 years old man came with the chief complaint of shortness of breathing. The patient felt the chief complaint since two years ago with getting worse during mild physical activity. The symptom got better during rest or slept with one pillow without complaining of dyspnea. One year ago, the patient started to feel palpitation disappear and arise with shortness of breathing. The patient got syncope two weeks ago during mild activities after a short period of breathlessness. For the vital sign, blood pressure was at 90/60 mmHg, blood pulse was 67 bpm irregular, breath frequency was 17x/min, and oxygen saturation was 99% room air. The electrocardiogram (ECG) showed atrial fibrillation with regular ventricular rate and left bundle branch block morphology of the QRS complex with Q wave at anterior precordial. The patient also checked for electrocardiography and ambulatory ECG monitoring using Holter. The patient was diagnosed with obstructive hypertrophy cardiomyopathy (OHCM), atrial fibrillation with regular ventricular rate and given Dabigatran 110 mg twice daily, metoprolol XL 12,5 mg once daily, and furosemide 10mg once daily for his medication.Conclusion: Theoretically, myectomy is the best option for this case; however, due to limited high-volume hospitals in Indonesia doing myectomy for hypertrophic obstructive cardiomyopathy, alcohol septal ablation may be an alternative option if the medication was no longer adequate to improve symptoms.

Mechanisms of left ventricular dyssynchrony: A multinational SPECT study of patients with bundle branch block

BackgroundTo better understand the mechanisms of left ventricular (LV) mechanical dyssynchrony (LVMD), we explored the relative contributions of QRS duration (QRSd), LV ejection fraction (EF), volumes and scar to LVMD measured by gated single-photon emission tomography in a population of consecutive patients with left bundle branch block (LBBB) and right bundle branch block (RBBB) compared to controls. MethodsMyocardial perfusion imaging studies of 275 LBBB and 83 RBBB patients from three centers were analyzed. LVMD was defined as an abnormal phase bandwidth or phase standard deviation. Hospital and gender-specific normal values were obtained from 172 controls. ResultsThe prevalence of LVMD was 85 and 40% in LBBB and RBBB, respectively. Ejection fraction, scar severity, and LBBB morphology independently explained 70% of variance seen in PhaseBW. Ejection fraction had the highest area under the curve (AUC 0.918) in the receiver operating characteristics analysis of LVMD with an optimal cut-off of 47% (sensitivity 73% and specificity 98%). Notably, QRSd was not predictive. ConclusionLV mechanical dysfunction plays a greater role than conduction abnormality in the genesis of LVMD, a finding that is intriguing in the context of contemporary literature which suggests that QRSd is the parameter that is most predictive of CRT response.

Short Term Predictors of Success after Cardiac Resynchronization Therapy

AbstractBackground: In patients with symptomatic Heart Failure (HF) and wide QRS duration, cardiac resynchronization therapy (CRT) causes reduction of morbidity and mortality. However, it's unclear which patient features predict short‐term response to this device therapy. Aim of the Work: The research aimed to study which cases characteristics could expect short-term clinical and echocardiographic response to CRT. Subjects and methods: This prospective cohort study involved 40 patients indicated for CRT device. The study was conducted in the cardiology departments, faculty of medicine, Zagazig University, and Police hospital at the period from October 2018 to October 2020. Clinical, laboratory, electrocardiographic, and echocardiographic assessments were performed pre and six months after implantation. Results: Forty patients undergoing CRT implantation were included among which, 30 (75%) patients were considered responders after six months. From the present study, the responders to CRT were more frequently to be females with younger age than non -responders. Non-ischemic HF, left bundle branch block (LBBB) morphology and New York Heart Association (NYHA) functional class III were significantly more frequent in responders. Furthermore, responders had significantly wider baseline QRS duration, smaller baseline LV diastolic and systolic dimension and volumes, greater ejection fraction, lower levels of brain natriuretic peptide (BNP), and more baseline intra-ventricular dyssynchrony. Conclusion: We concluded that pre-implantation independent Predictors of good CRT response are LBBB morphology, septal to posterior wall mechanical delay, wide QRS duration, interventricular mechanical delay, NYHA functional class III, and lower levels of BNP. Large scale study is recommended for further verification of study results.

Right Bundle Branch Block Morphology After Right Ventricular Endocardial Pacing – When Should a Cardiologist Begin to Worry ?

Even though the left bundle branch block (LBBB) morphology in the surface electrocardiogram (ECG) is expected after right ventricular endocardial pacing, the right bundle branch block (RBBB) morphology may be paradoxically seen in around 8 to 10% of patients. The paced RBBB morphology should be given special attention in terms of safe RV pacing or septal and free wall perforation. Simple techniques such as moving the leads V1-2 to one interspace lower than standard (Klein maneuver) and combining frontal QRS axis between -30° to -90°, precordial transition point at or within V3, and absence of S wave in lead I as an algorithmic approach may correctly identify the pacemaker lead in right ventricle with high sensitivity, specificity, and positive predictive value.

Clinical profile and therapeutic strategies in patients with arrhythmogenic cardiomyopathy treated in a national reference institute

To determine the epidemiological, clinical, electrocardiographic, imaging characteristics and main therapeutic strategies performed in patients with arrhythmogenic cardiomyopathy treated in a national reference cardiovascular institute. Observational, descriptive and retrospective study that attempts to identify the clinical characteristics, complementary tests and therapeutic strategies performed in patients with arrhythmogenic cardiomyopathy treated at the Instituto Nacional Cardiovascular - INCOR EsSalud in Lima, Peru. Thirteen patients were found with arrhythmogenic cardiomyopathy. The median age at which the diagnosis was made was 38.2 years and 69.3% were male. The most frequent clinical manifestations were tachycardic palpitations (92.3%), presyncope (84.6%) and heart failure (69.2%). 23% of the patients suffered a cardiac arrest. All the patients presented at least one episode of ventricular tachycardia, 92.3% with complete left bundle branch block morphology and upper axis. 76.9% received an implantable cardioverter defibrillator (ICD), 15.3% underwent ablation and 15.3% received a heart transplant. 84.6% of the patients live to this day. Arrhythmogenic cardiomyopathy predominantly affected the young and male population. All the patients had a potentially fatal ventricular arrhythmia. Biventricular disease by echocardiography and cardiac magnetic resonance occurred in 69.2% and 100% of the cases, respectively. The therapeutic strategies used were antiarrhythmic medical treatment, placement of an ICD as secondary prevention, ablation, and heart transplantation. To date, 84.6% of patients survive.

Alternating wide complex tachycardia after surgical aortic valve replacement

A 51-year-old male developed recurrent episodes of palpitations and pre-syncope after surgical aortic valve replacement. Electrocardiograms after surgery revealed a wide complex tachycardia with alternating left bundle branch and right bundle branch block morphologies. An electrophysiology study (EPS) demonstrated typical bundle branch reentry ventricular tachycardia (BBRVT) treated successfully with right bundle ablation. We demonstrate the key diagnostic features of BBRVT on EPS, describe the circuit of BBRVT with explanation of the HV pseudointerval, and highlight the association of BBRVT and valve replacement.

Segment length in cine (SLICE) strain analysis: a practical approach to estimate potential benefit from cardiac resynchronization therapy

BackgroundSegment length in cine (SLICE) strain analysis on standard cardiovascular magnetic resonance (CMR) cine images was recently validated against gold standard myocardial tagging. The present study aims to explore predictive value of SLICE for cardiac resynchronization therapy (CRT) response.Methods and resultsFifty-seven patients with heart failure and left bundle branch block (LBBB) were prospectively enrolled in this multi-center study and underwent CMR examination before CRT implantation. Circumferential strains of the septal and lateral wall were measured by SLICE on short-axis cine images. In addition, timing and strain pattern parameters were assessed. After twelve months, CRT response was quantified by the echocardiographic change in left ventricular (LV) end-systolic volume (LVESV). In contrast to timing parameters, strain pattern parameters being systolic rebound stretch of the septum (SRSsep), systolic stretch index (SSIsep-lat), and internal stretch factor (ISFsep-lat) all correlated significantly with LVESV change (R − 0.56; R − 0.53; and R − 0.58, respectively). Of all strain parameters, end-systolic septal strain (ESSsep) showed strongest correlation with LVESV change (R − 0.63). Multivariable analysis showed ESSsep to be independently related to LVESV change together with age and QRSAREA.ConclusionThe practicable SLICE strain technique may help the clinician to estimate potential benefit from CRT by analyzing standard CMR cine images without the need for commercial software. Of all strain parameters, end-systolic septal strain (ESSsep) demonstrates the strongest correlation with reverse remodeling after CRT. This parameter may be of special interest in patients with non-strict LBBB morphology for whom CRT benefit is doubted.

A Computer Simulation Research of Two Types of Cardiac Physiological Pacing

This manuscript adopted the cardiac modeling and simulation method to study the problems of physiological pacing in clinical application. A multiscale rabbit ventricular electrophysiological model was constructed. We simulated His-bundle pacing (HBP) treatment for left bundle branch block (LBBB) and atrioventricular block (AVB), and left bundle branch pacing (LBBP) treatment for LBBB by setting various moments of the stimulus. The synthetic ECGs and detailed electrical activities were analyzed. Our electrophysiological model accurately simulated the normal state, HBP, and LBBP. The synthetic ECG showed that QRS duration was narrowed by 30% after HBP correction for LBBB. For LBBB correction with LBBP, the synthetic ECGs of LBBP starting before 30 ms (if the end of atrial excitation is set as 0 ms) presented right bundle branch block (RBBB), and those of LBBP starting at 30–38 ms were synchronous, while those of LBBP starting after 42 ms possessed LBBB morphologies. The best pacing results were obtained when LBBP started at 34 ms. This manuscript verified the feasibility of the constructed ventricular model, and studied the physiological pacing mechanism. The results showed that HBP realized correction for AVB and high LBBB. The performance of LBBP can be improved by applying the stimulus within a specific period of time (0–8 ms) after atrial excitation.

Role of an extensive diagnostic work-up in the detection of concealed cardiomyopathies in athletes with premature ventricular complexes and implications for sports' eligibility assessment

Abstract Background Premature ventricular complexes (PVCs) are a common clinical problem and a critical issue with regard to sports eligibility in sportsmen. Although PVCs can be considered a benign feature of the athlete's heart adaptive phenotype, they may also be the only clinical manifestation of a concealed cardiomyopathy, potentially heralding sudden cardiac death (SCD) during sports activity. The optimal diagnostic evaluation of athletes with PVCs is currently uncertain. Purpose To evaluate the diagnostic contribution and the implications for sports eligibility assessment of a thorough non-invasive and invasive work-up including electroanatomical mapping (EAM) and endomyocardial biopsy (EMB) in athletes with PVCs. Methods We conducted a prospective, single-arm, open-label double center study. All consecutive athletes presenting for evaluation at our institution after being disqualified from participating in sports due to PVCs were included in our study. These athletes underwent a baseline non-invasive diagnostic protocol with transthoracic echocardiogram and gadolinium enhanced cardiac magnetic resonance imaging (cMRI). Subsequently, an invasive diagnostic work-up was performed, including EPS with programmed electrical stimulation, EAM and EAM-guided EMB if deemed necessary. When clinically indicated, catheter ablation was performed. Sports eligibility status was re-assessed at six months' follow-up according to Italian sports medicine guidelines. Results After diagnostic evaluation, 20 subjects out of 107 (19%) had a diagnosis of heart disease, most commonly myocarditis (n=8), arrhythmogenic right ventricular cardiomyopathy (ARVC, n=7) or dilated cardiomyopathy (DCM, n=2). On multivariate logistic-regression analysis, QRS complex/T wave abnormalities on ECG (OR 23), non left bundle branch block and inferior axis PVC morphology (OR 13), echocardiogram abnormalities (OR 24) and low-voltage areas on EAM (OR 33) were significantly associated with diagnosis of a concealed cardiac disease. Nondiagnostic abnormalities on cMRI were common in this population of athletes, prevalently involving the right ventricle. EAM-guided EMB was performed in 12 subjects (11%) and catheter ablation in 56 (52.3%). After six months, 63 athletes (59%) were judged eligible to participate in competitive sports and 23 subjects (21%) were deemed eligible to participate in non-competitive sports. Conclusions Almost one fifth of sportsmen presenting with PVCs have a concealed heart disease, most commonly myocarditis or ARVC. Non-outflow tract PVCs' morphology and abnormalities on ECG, echocardiogram and EAM are predictive of structural heart disease's detection, whereas nondiagnostic findings on cMRI can be misleading in athletes. Invasive diagnostic tests, including EAM and EAM-guided EMB, play a critical role in case of diagnostic uncertainty. More than ¾ of subjects were judged eligible to participate in sports at 6 months' follow-up. Funding Acknowledgement Type of funding source: None

Sustained ventricular tachycardia of left, right or both bundle branch block morphology in patients with Arrhythmogenic Cardiomyopathy

Abstract Aims In arrhythmogenic cardiomyopathy (ACM) sustained monomorphic ventricular tachycardia (VT) typically displays left bundle branch block (LBBB) morphology. Sustained VT with right bundle branch block (RBBB) morphology is very rare despite the frequent left ventricular involvement. The present study sought to assess the prevalence of spontaneous sustained LBBB-VT, RBBB-VT or both as well as clinical and genetic differences associated with these VT types. Methods and results Twenty-six centers from 11 European countries provided information on 952 patients with ACM and >1 episode of sustained VT observed during the patients' clinical course. VT was classified as: LBBB-VT; RBBB-VT or LBBB+RBBB-VT. Among 952 patients, 881 (92.5%) had LBBB-VT alone, 71 (7.5%) had RBBB-VT [alone in 42 (4.4%) patients or with LBBB-VT in 29 (3.0%) patients]. Male prevalence was 90.5%, 79.2% and 55.9% in the RBBB-VT, LBBB-VT and LBBB+RBBB-VT groups, respectively (P=0.001). Patients' age at first VT did not differ amongst the 3 VT groups. ICD implantation was more frequent for the RBBB-VT and the LBBB+RBBB groups (≈90% each) vs. 67.9% for the LBBB-VT group (P=0.001). Death incidence (9.5%–17.2%) was not significantly different between the 3 groups (P=0.425). Plakophylin-2 mutations predominated in the LBBB-VT and LBBB-VT+RBBB-VT groups (47.2% and 27.3%, respectively) and Desmoplakin mutations in the RBBB-VT group (36.7%). Conclusion This large European survey demonstrates: 1) Sustained RBBB-VT is documented in 7.5% patients with ACM; 2) Males markedly predominate in the RBBB-VT and LBBB-VT groups but not in the LBBB+RBBB VT group; 3) Distribution of desmosomal mutations appears to be different in the 3 VT groups. Funding Acknowledgement Type of funding source: None

Lateral left ventricular lead position is superior to posterior position in long-term outcome of patients who underwent cardiac resynchronization therapy.

AimsPreferring side branch of coronary sinus during cardiac resynchronization therapy (CRT) implantation has been empirical due to the limited data on the association of left ventricular (LV) lead position and long‐term clinical outcome. We evaluated the long‐term all‐cause mortality by LV lead non‐apical positions and further characterized them by interlead electrical delay (IED).Methods and resultsIn our retrospective database, 2087 patients who underwent CRT implantation were registered between 2000 and 2018. Those with non‐apical LV lead locations were classified into anterior (n = 108), posterior (n = 643), and lateral (n = 1336) groups. All‐cause mortality was assessed by Kaplan–Meier and Cox analyses. Echocardiographic response was measured 6 months after CRT implantation. During the median follow‐up time of 3.7 years, 1150 (55.1%) patients died—710 (53.1%) with lateral, 78 (72.2%) with anterior, and 362 (56.3%) with posterior positions. When we investigated the risk of all‐cause mortality, there was a significantly lower rate of death in patients with lateral LV lead location when compared with those with an anterior (P < 0.01) or posterior (P < 0.01) position. Multivariate analysis after adjustment for relevant clinical covariates such as age, sex, ischaemic aetiology, left bundle branch block morphology, atrial fibrillation, and device type revealed consistent results that lateral position is associated with a significant risk reduction of all‐cause mortality when compared with anterior [hazard ratio 0.69; 95% confidence interval (CI) 0.55–0.87; P < 0.01] or posterior (hazard ratio 0.84; 95% CI 0.74–0.96; P < 0.01) position. When echocardiographic response was evaluated within the lateral group, patients with an IED longer than 110 ms (area under the receiver operating characteristic curve, 0.63; 95% CI 0.53–0.73; P = 0.012) showed 2.1 times higher odds of improvement in echocardiographic response 6 months after the implantation.ConclusionsIn this study, we proved in a real‐world patient population that after CRT implantation, lateral LV lead location was associated with long‐term mortality benefit and is superior to both anterior and posterior positions. Moreover, patients with this position showed the greatest echocardiographic response over 110 ms IED.

P320Prevalence of QRS 120 to 150 ms and QRS more than or equal to 150 ms from patients with left ventricular ejection fraction less than or equal to 35% in sinus rhythm and left bundle branch block

Abstract Introduction To date, no study in published literature has investigated the prevalence of patients with QRS ≥120 ms (ESC/EHRA Guidelines) and QRS ≥150 ms (ACC/AHA/HRS Guidelines) from patients with left ventricular ejection fraction (LVEF) ≤35% in sinus rhythm (SR) with left bundle branch block (LBBB) morphology, both said QRS durations were included in the criteria of Class I indication for cardiac resynchronization therapy (CRT) implantation. Purpose To determine the prevalence of patients with QRS 120-150 ms and QRS ≥150 ms from patients with LVEF ≤35% in SR and LBBB, to classify these patients to ischaemic cardiomyopathy (ICM) and nonischaemic cardiomyopathy (NICM), and to determine their demographics in terms of age, sex, and comorbidities Methods This is a cross-sectional study performed from January to September 2016. Data collection was performed which consists of 2-D echocardiogram with LVEF ≤35% in SR and LBBB, from which 2 groups of QRS 120-150 ms and ≥150 ms with their demographic profiles such as age, sex, and comorbidities will be identified and analyzed using percentage or proportion. Results The sample size in the study period was composed of 10,113 patients, of whom 1% (135) had LVEF ≤35% in SR. From 135 patients, 11% (15) had LBBB with QRS ≥120 ms. From 135 patients, 7% (9) had QRS 120-150 ms and also 7% (9) had QRS ≥150 ms. All patients who had QRS 120-150 ms were ICM while those with QRS ≥150 ms, 56% (5) were ICM and 44% (4) were NICM. Among patients with QRS 120-150 ms, youngest age was 50, median age was 67, and oldest age was 84, while among patients with QRS ≥150 ms, youngest age was 50, median age was 66, and oldest age was 82. Among those with QRS 120-150 ms, 67% (6) were males and 33% (3) were females whereas those with QRS ≥150 ms, 78% (7) were males and 22% (2) were females. Both groups of QRS 120-150 ms and ≥150 ms had the same identified comorbidities: coronary artery disease (CAD), hypertension (HTN), diabetes mellitus (DM), dyslipidemia and end stage renal disease (ESRD). Those with QRS 120-150 ms, 67% (6) had both CAD and DM, 56% (5) had HTN, 22% (2) had dyslipidemia and 11% (1) had ESRD, whereas those with QRS ≥150 ms, 78% (7) had CAD, 56% (5) had HTN, 44% (4) had DM, and 11% (1) had both dyslipidemia and ESRD. Conclusions There was both 7% prevalence of patients with QRS 120-150 ms and QRS ≥150 ms from patients with LVEF ≤35% in SR and LBBB. All patients with QRS 120-150 ms were ICM while majority of those with QRS ≥150 ms were ICM. In both groups of QRS duration, youngest age was 50; median age of QRS 120-150 ms was 67 whereas QRS ≥150 ms was 66; and with QRS 120-150 ms, patients who were affected were older (84 years old vs 82 years old). Both QRS 120-150 ms and ≥150 ms were predominantly males with CAD, HTN, and DM as identified important risk factors.

Wide and narrow QRS tachycardias: What is the mechanism?

A 50-year-old lady was referred for radiofrequency catheter ablation of narrow QRS tachycardia that was terminated with intravenous adenosine. Twelve-lead Electrocardiogram (ECG) was normal during sinus rhythm. The electrophysiological study showed an Atrio-Hisian (AH) interval of 104 ms and Hisio-Ventricular (HV) interval of 45 ms during sinus rhythm. Atrial pacing reproducibly induced regular broad (left bundle branch block morphology) and narrow QRS tachycardias. A spontaneous premature ventricular ectopic from right ventricular apex has resulted in transition of the tachycardia from wide to narrow. What are the likely mechanisms?

COMPARATIVE ANALYSIS OF MORPHOLOGICAL CRITERIA FOR DIFFERENTIAL DIAGNOSTICS OF WIDE QRS COMPLEX ARRHYTHMIAS WITH LEFT BUNDLE BRANCH BLOCK MORPHOLOGY

Introduction. Determination of ventricular and supraventricular arrhythmias with left bundle branch block morphology (LBBB) seems to be one of the most complex diagnostic tasks when P waves are not clearly identifiable on 12-lead ECG. Previously described criteria for differential diagnosis of wide QRS arrhythmias had low accuracy especially for patients from various clinical groups and also those taking antiarrhythmic drugs. When patient’s clinical data, medical history or physical examination results are not available the number of misdiagnosis may increase leading to improper treatment. Therefore, development of new temporal and amplitude based characteristics of wide QRS complex arrhythmias with LBBB morphology in patients of any clinical groups is an important task.Methods. Twenty-eight consecutive patients with wide QRS premature beats and LBBB morphology identified by 24-hour and long-term ECG monitoring (ZAO “INCART”, Russia) were enrolled in the study. Fourteen patients had premature atrial contractions (PAC) and fourteen patients had premature ventricular contractions (PVC) during sinus rhythm. For each patient 10 typical single wide QRS complexes in 12 ECG leads were analyzed. The duration of QRS complexes, time intrinsic deflection (TID) and electrical axis of the heart were determined automatically in 12 leads ECG using KT Result 3 software (ZAO “INCART”, Russia). The experts assessed morphology of the QRS complexes and transition zone location in leads V1-V6. ROC analysis with optimal cut-off value level evaluation as well as calculation of sensitivity (SV), specificity (SP) and diagnostic accuracy (ACC) were performed for qualitative and quantitative assessment of diagnostic value of PAC and PVC amplitude and temporal characteristics. Comparison of diagnostic values of wide QRS complex morphological and temporal criteria was performed based on the AUC difference and the corresponding p-value assessment.Results. The results of study found out that V5, V1 leads were more informative for assessment of QRS complex morphology and duration while V1 and V4 leads were more informative for TID calculation in differential diagnosis of wide QRS complexes arrhythmias with LBBB morphology. PAC with aberrant conduction had the following characteristics: TID &lt; 68 ms in V1 lead and TID &lt; 62 ms in V4 lead; QRS &lt; 136 ms; transition zone in the leads V5, V6; QS, rS or RS complexes (with S&gt; R) with low-amplitude r/R waves in leads V1-V4; electric axis of the heart less than 80° in standard leads. In all cases PVCs were characterized by QRS &gt; 160 ms and TID &gt; 88 ms in V1-V6 leads.Conclusions. New various criteria which can improve differential diagnosis of wide QRS complexes with LBBB morphology were identified in this study. These criteria should be tested in a larger group of patients with various forms of wide QRS complex arrhythmias and different PVC localizations including information of structural heart diseases due to the small sample size in this study.Conflicts of Interest: Viktor M. Tikhonenko - CEO (Director General) of the Institute of Cardiology Technics (INCART), Saint-Petersburg, Russia.

P644 A not so innocent athlete"s heart

Abstract We report the case of a 17 years old athlete who resorted to the emergency service for palpitations and dizziness during exercising. He mentioned two episodes of syncope associated with exercise in the last 6 months. He was tachycardic (200 bpm) and hypotensive (85/56 mmHg). The electrocardiogram showed regular wide complex tachycardia with left bundle branch block morphology with superior axis restored to sinus rhythm after electrical cardioversion. In sinus rhythm, it showed T-wave inversion in V1-V5. Patient was admitted for study. Transthoracic echocardiography demonstrated mild enlargement and dysfunction of the right ventricle (RV) with global hypocontractility (FAC of 29%). The cardiac magnetic resonance (CMR revealed a RV end-diastolic volume indexed to surface body area of 180 mL/m2, global hypocinesia and RV dyssynchrony, subepicardial late enhancement in the distal septum and in the middle segment of the infero-septal wall. The patient underwent genetic study which showed a mutation in the gene that encodes the desmocolin-2 protein (DSC-2) involved in the pathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC). According to the 2010 modified Task Force criteria for this diagnosis, the patient presented 4 major criteria for ARVC (characteristic ventricular tachycardia, repolarization and morphofunctional changes and the presence of pathogenic mutation) and the diagnosis was made. Thus, given the clinical presentation, it was implanted a subcutaneous cardioverter and patient is currently in follow-up at the Cardiology service. ARVC is present in 1 to 1000-5000 people and is responsible for 20% of all sudden cardiac deaths, especially in athletes. Diagnosis is based on structural, functional, electrophysiological and genetic criteria reflecting underlying histological changes. This case shows and reviews the essential characteristics to the disease recognition and, therefore, to the prevention of its most feared complication: sudden cardiac death.

P1733 Late onset of arrhytmogenic cardiomyopathy, unmasked by myocarditis - when multimodality imaging solves the puzzle

Abstract Introduction Arrhythmogenic cardiomyopathy (AC) is a genetic disease, associated with arrhythmic sudden death in young people. Since inflammation might be also present, differential diagnosis with myocarditis is necessary. We present a challenging case, initially diagnosed with ventricular tachycardia (VT) and acute myocardial infarction (AMI), in which multimodality imaging changed the initial diagnosis. Clinical case. A 68-year old woman with dyslipidaemia and hypertension was admitted with chest pain, negative T waves in anterior leads, epsilon wave in V1, V2 (Fig. A, B), negative troponin I (TpI), and elevated NT-proBNP (342 ng/ml). One month before, she was hospitalized for a monomorphic VT with left bundle branch block (LBBB) pattern, with hemodynamic instability, cardioverted electrically to sinus rhythm. Increased TpI suggested an AMI. She recalls an episode of flu with high fever (39°C) before admission. At current admission, transthoracic echo (TTE) revealed LVEF 52%, severe lateral wall hypokinesia, severe RV dysfunction with fractional area change 23%, and TAPSE 15 mm. Coronary angiography excluded significant lesions. Speckle tracking echo(STE) revealed patchy areas of decreased LV myocardial deformation (Fig. C), and decreased basal deformation in RV free wall(Fig. D). Cardiac magnetic resonance (CMR) revealed LVEF 59%, lateral and septal wall hypokinesia, late gadolinium enhancement (LGE) in mid-ventricular lateral wall and interventricular septum (Fig. F), with correspondent increased extracellular volume (ECV) &amp;gt;30%, increased native T1 time, increased T2 mapping, and small pericardial effusion (7 mm); RV was dilated (diastolic volume 107 ml/m2 and systolic volume 69 ml/m2), with severely decreased RV ejection fraction (RVEF) of 35%, hypokinesia of free wall, dyssynchronous contractions, and microaneurysms (Fig. E, F). Diagnosis was concluded for AC with delayed onset, revealed by an acute myocarditis. Betablocker, ACEI, and implantable cardioverter defibrillator (ICD) in secondary prevention were decided. Relatives were screened for the presence of AC. Patient`s daughter presented 8000 isolated monomorphic ventricular ectopic heart beats with LV origin, no echo signs, but incipient signs of AC on CMR (increased ECV on T1 mapping in 7 LV myocardial segments, without LGE). Discussion We presented a rare case of late arrhythmic onset of AC in a patient, in which the first aetiology of VT was considered to be ischaemic. VT with LBBB morphology can be caused by myocarditis, AMI, or AC. Similarly, epsilon wave with negative T waves in precordial leads may have multiple aetiologies. In our case, multimodality imaging approach excluded AMI and suggested an inflammatory cause for VT. CMR allowed the identification of morphologic condition AC and the trigger condition of myocarditis. Conclusions Our case highlights the importance of a multimodality imaging approach in diagnosing AC and myocarditis, for a correct and complete management. Abstract P1733 Figure.

Evaluating Electrocardiography-Based Identification of Cardiac Resynchronization Therapy Responders Beyond Current LeftBundle Branch Block Definitions.

This study aimed to evaluate the association of 4 left bundle branch block (LBBB) definitions and their individual ECG characteristics with clinical outcome. Furthermore, it aimed to combine relevant outcome-associated electrocardiographic (ECG) characteristics into a novel outcome-based definition. LBBB morphology is associated with positive response to cardiac resynchronization therapy. However, there are multiple LBBB definitions. Associations with outcomes may differ between definitions and depend on varying contributions of the individual ECG characteristics that these LBBB definitions are composed of. A retrospective multicenter study was conducted in 1,492 cardiac resynchronization therapy patients. Patients were classified as LBBB or non-LBBB according to definitions provided by the European Society of Cardiology, American Heart Association, MADIT-CRT (Multicenter Automatic Defibrillator Implantation with Cardiac Resynchronization Therapy) trial, and according to Strauss et al., the primary endpoint was left ventricular assist device implantation, cardiac transplantation, and all-cause mortality. LBBB classification differed significantly between the 4 definitions (kappa coefficients ranging from 0.09 to 0.92). The American Heart Association definition correlated the least (0.09 to 0.12) with the other definitions. Only 13.8% of patients were classified as LBBB by all definitions. During a follow-up period of 3.4 ± 2.4 years, 472 (32%) patients experienced the primary endpoint. For each LBBB definition survival analysis showed a significant association of LBBB with outcome, with relative risk reduction ranging from 39% to 43%. Each LBBB definition included characteristics that were not associated with outcome. Combining outcome-associated ECG characteristics into a novel prediction model did not significantly improve diagnostic performance (relative risk reduction 43%). The classification of LBBB is highly dependent on the LBBB definition used. However, each LBBB definition provides a comparable difference in risk of adverse clinical events between LBBB and non-LBBB patients. Combining individual outcome-associated ECG-characteristics into a novel prediction model does not improve association with outcome.

P2568Larger vectorcardiographic QRS area is associated with increased risk of heart failure development among left bundle branch block patients: a register-based cohort study

Abstract Background QRS morphology including left bundle branch block (LBBB) and duration remain the most widely used surrogate markers in the 12-lead electrocardiogram (ECG) for assessing ventricular dyssynchrony and predicting future burden of heart failure (HF) and cardiovascular mortality. However, the vectorcardiographic QRS area has recently been proposed and evidence suggest that this marker may more accurately predict HF development. Purpose The aim of this study was to investigate the association between vectorcardiographic QRS area and risk of HF development in LBBB patients. Methods From 2001–2015, the Copenhagen General Practitioners' Laboratory was used to identify patients with a first-time LBBB ECG (QRS&gt;120 ms; LBBB morphology), from which QRS area was derived using the Kors transformation method and grouped into quartiles. Outcome was a composite of HF diagnosis, redeemed prescriptions of loop diuretics, or death from HF. Death from other causes was accounted for as a competing risk. Results We included a total of 2843 LBBB patients who were free of heart failure (median age, 70 years; female, 58%; ischemic heart disease, 9%). QRS area quartiles comprised Q1, 67–158 μVs; Q2, 159–189 μVs; Q3, 190–228 μVs; and Q4, 229–739 μVs. During 6-month, 1-year, and 5-year follow-up, 9%, 12%, and 28% of patients reached the combined HF endpoint, and 1%, 2%, and 8% of patients died from other causes, respectively (Figure 1). After multivariable adjustment, the highest QRS area quartile, Q4, was associated with increased HF risk (adjusted hazard ratio, 1.64; 95% confidence interval, 1.35–2.00) compared with the lowest quartile, Q1. We did not observe any significant increase in HF risk for remaining quartiles (Q2 or Q3 vs. Q1). Figure 1 Conclusions Among primary care patients with newly discovered LBBB, a large vectorcardiographic QRS area (229–739 μVs) is associated with increased risk of developing the incident, combined HF endpoint. This indicates that the QRS area derived using the Kors method may serve as a valuable prognostic marker when assessing risk of HF in patients with LBBB.

Catheter Ablation of Ventricular Arrhythmias Originating From the Pulmonary Sinus Cusp in Pediatric Patients: A Single-Center Retrospective Study.

Objective: There are few reports of ventricular arrhythmias (VAs) originating from the pulmonary sinus cusp (PSC) in pediatric patients. Thus, we investigated the ablation of PSC-VAs in pediatric patients.Study Design: Clinical, echocardiographic, and ablation data were reviewed in 10 consecutive symptomatic children who underwent successful ablation of VAs of PSC origin at our center between March 2014 and June 2018.Results: The 10 patients' weights ranged from 29 to 63.5 kg, and all had structurally normal hearts and VAs with left bundle branch block (LBBB) morphologies and inferior axes. The initial ablation was performed in the right ventricular outflow tract (RVOT) or the aortic sinus cusp, which failed to terminate the VAs in nine patients. The successful ablation site was in the right cusp (RC) in seven patients, the anterior cusp in two patients, and the left cusp (LC) in one patient. The earliest potential recorded at the PSC ablation site preceded the onset of the QRS complex during VAs by 29.4 ± 4.9 ms.Conclusions: VAs with a LBBB morphologies and inferior axes may originate within the PSC of children. Ablation was effective and safe for the eradication of VAs originating from the PSCs in children. Due to the particularity of ablations in pediatric patients, mapping of PSCs should be considered when ablation fails in the RVOT.

Clinical and electrophysiological characteristics of idiopathic ventricular arrhythmias originating from the slow pathway region

The slow pathway region (SPR) is commonly targeted during ablation of atrioventricular nodal reentrant tachycardia. However, its role in idiopathic ventricular arrhythmias (IVAs) remains unknown. The purpose of this study was to describe the electrocardiographic and electrophysiological characteristics of IVAs that were successfully ablated from the SPR. Medical records of consecutive patients undergoing ablation of IVAs in the para-Hisian region between 2010 and 2018 were reviewed to identify subjects whose ventricular arrhythmias were targeted from the SPR. Among 63 patients with para-Hisian IVAs undergoing ablation, the SPR was targeted in 12 (20%; mean age 64 ± 7 years; 9 men). All patients presented with ventricular premature depolarizations manifesting left bundle branch block morphology with variable precordial transition (leads V2-V5) and a mean QRS duration of 131 ± 11 ms. In all cases, leads I and aVL had positive forces (R or Rs) and lead aVR had negative forces (QS or Qr). In the majority of cases, lead II had positive forces (R or Rs; n = 9 [75%]) and lead III had negative forces (rS or QS; n = 9 [75%]). Mean activation at the SPR was 31 ± 5 ms pre-QRS. All patients had initial ablation with radiofrequency, resulting in junctional rhythm in 9 (75%); 3 (25%) patients required additional cryoablation. Ablation was successful in 11 patients (92%). One patient required a permanent pacemaker for heart block but subsequently recovered intrinsic conduction. The SPR can be a source of IVAs, which can be safely and successfully ablated in most cases using radiofrequency energy. IVAs arising from this location manifest unique electrocardiographic features.