The QRS frontal plane axis changes during left bundle branch block after transcatheter aortic valve replacement

BACKGROUND AND AIMS

Left bundle branch block (LBBB) is common after transcatheter aortic valve replacement (TAVR) and associated with a left or normal QRS axis. We aim to assess the QRS frontal plane axis shift changes during LBBB after TAVR and determine if the risk of procedure-related high degree atrioventricular block (AVB) is affected by QRS axis shift changes.

METHODS AND RESULTS

In a retrospective single-center study of 720 consecutive patients who underwent TAVR, 141 (19.6%) with normal baseline QRS duration developed a new LBBB after TAVR and constituted the study group. Most patients (59.6%) were females and the mean age of the cohort was 81.2 ± 6 years.

RESULTS

As compared with the baseline QRS axis before TAVR, the occurrence of LBBB was associated with a leftward QRS axis shift (by 40 ± 28.3°) in 73% of the study patients and a rightward (by 18.6 ± 19.4°) or no change in QRS axis in 25.6% and 1.4% of the study patients, respectively. A left QRS axis (-30°) was observed in 14.9% and 38.3% of the study patients before and after TAVR, respectively. The group of patients exhibiting a rightward or no QRS axis shift had a greater incidence of high degree AVB than the group of patients exhibiting a leftward QRS axis shift (18.4% vs. 6.8%, p = .056).

CONCLUSION

Although post TAVR-LBBB is associated with a leftward QRS axis shift in most patients, a non-negligible proportion of patients (27%) exhibited a rightward or no QRS axis shift. The latter group tend to have a higher risk of developing high degree AVB.

The R-wave amplitude in V1 on baseline electrocardiogram correlates with the occurrence of high-degree atrioventricular block following left bundle branch block after transcatheter aortic valve replacement

AIMS

Several procedural and electrocardiogram (ECG) parameters have been associated with the occurrence of high-degree atrioventricular block (AVB) requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement (TAVR). We hereunder sought to assess if the baseline R-wave amplitude in V1 ECG lead of patients with normal QRS duration undergoing TAVR is associated with a higher patient's risk for developing high-degree AVB following left bundle branch block (LBBB).

METHODS AND RESULTS

In this retrospective single-centre study in 720 consecutive patients who underwent TAVR, 141 (19.6%) patients with normal QRS duration developed a new LBBB after TAVR. The 24 (17%) patients who underwent PPI for reasons other than high-degree AVB were excluded from further analysis. In the remaining 117 study patients, 14 (12%) developed high-degree AVB requiring PPI (Group 1) while the remaining 103 (88%) patients did not (Group 2). There were no significant differences in baseline demographic or procedural characteristics nor in PR interval, QRS duration, and QRS axis between these two groups. The incidence of left anterior hemiblock was higher in Group 1 (3 of 14, 21.4%) than that in Group 2 (9 of 103, 8.7%), but the difference was not statistically significant (P = 0.156). The R-wave amplitude in V1 was smaller in Group 1 than that in Group 2 (0.029 ± 0.04 mV vs. 0.11 ± 0.14 mV, P = 0.0316). In the receiver-operating characteristics analysis, the cutoff for R-wave amplitude pre-TAVR was 0.03 mV, area under the curve = 0.7219 (P = 0.0002).

CONCLUSION

The R-wave amplitude in lead V1 during baseline ECG in patients with normal QRS duration may predict the occurrence of high-degree AVB following new LBBB after TAVR.

Novel Approaches for the Diagnosis of Concealed Nodo-Ventricular and His-Ventricular Pathways

BACKGROUND

Confirming the presence and participation of concealed nodo-ventricular (cNV) or His-ventricular (cHV) pathways in tachyarrhythmias is challenging. We describe novel observations to aid in diagnosing cNV or cHV pathways.

METHODS

We present 7 cases of cNV and cHV pathway-mediated arrhythmias and focus on several laboratory observations: (1) differential ventricular overdrive pacing (VOD) from the base versus apex, (2) response to His refractory premature ventricular complexes, (3) paradoxical atriohisian response (shorter atriohisian interval during tachycardia than that during sinus rhythm) in long RP tachycardia, and (4) the role of adenosine to aid in the diagnosis.

RESULTS

Three cases underwent differential VOD during tachycardia. All demonstrated a shorter postpacing interval minus tachycardia cycle length during basal pacing than apical pacing with one case exhibiting apical VOD results compatible with atrioventricular nodal reentrant tachycardia. Basal VOD was useful for localizing the ventricular connection in a case with cHV pathway. In 3 cases, His refractory premature ventricular complexes reset the tachycardia without conduction to the atrium, which excluded the involvement of an atrioventricular pathway or atrial tachycardia, or atrioventricular nodal reentrant tachycardia alone. One case had His refractory premature ventricular complexes followed by subsequent constant AA interval and then tachycardia termination, suggesting a bystander cNV pathway involvement. Two cNV pathway cases presented with long RP tachycardia had paradoxical atriohisian shortening of >15 ms, suggesting parallel activation of the atrium and the atrioventricular node. Adenosine terminated the tachycardia with retrograde block in 2 cases with cNV pathways but had no response on a cHV pathway.

CONCLUSIONS

cNV and cHV pathways mediated tachyarrhythmias can present with variable clinical presentations. We emphasize the important role of differential VOD sites, His refractory premature ventricular complexes that reset or terminate the tachycardia without conduction to the atrium, paradoxical atriohisian response in long RP tachycardia, and the use of adenosine for diagnosing cNV and cHV pathways.

Electrocardiographic findings in patients with arrhythmogenic cardiomyopathy and right bundle branch block ventricular tachycardia

AIMS

Little is known about patients with right bundle branch block (RBBB)-ventricular tachycardia (VT) and arrhythmogenic cardiomyopathy (ACM). Our aims were: (i) to describe electrocardiogram (ECG) characteristics of sinus rhythm (SR) and VT; (ii) to correlate SR with RBBB-VT ECGs; and (iii) to compare VT ECGs with electro-anatomic mapping (EAM) data.

METHODS AND RESULTS

From the European Survey on ACM, 70 patients with spontaneous RBBB-VT were included. Putative left ventricular (LV) sites of origin (SOOs) were estimated with a VT-axis-derived methodology and confirmed by EAM data when available.  Overall, 49 (70%) patients met definite Task Force Criteria. Low QRS voltage predominated in lateral leads (n = 37, 55%), but QRS fragmentation was more frequent in inferior leads (n = 15, 23%). T-wave inversion (TWI) was equally frequent in inferior (n = 28, 42%) and lateral (n = 27, 40%) leads. TWI in inferior leads was associated with reduced LV ejection fraction (LVEF; 46 ± 10 vs. 53 ± 8, P = 0.02). Regarding SOOs, the inferior wall harboured 31 (46%) SOOs, followed by the lateral wall (n = 17, 25%), the anterior wall (n = 15, 22%), and the septum (n = 4, 6%). EAM data were available for 16 patients and showed good concordance with the putative SOOs. In all patients with superior-axis RBBB-VT who underwent endo-epicardial VT activation mapping, VT originated from the LV.

CONCLUSIONS

In patients with ACM and RBBB-VT, RBBB-VTs originated mainly from the inferior and lateral LV walls. SR depolarization and repolarization abnormalities were frequent and associated with underlying variants.

Red Flags in Syncope: Clues for the Diagnosis of Idiopathic Ventricular Fibrillation

Idiopathic ventricular fibrillation is responsible for ≈5%-7% of aborted cardiac arrest, mainly striking subjects in their forties. Syncope caused by short-coupled rapid polymorphic ventricular tachycardia is frequently noted in a patient's past history. However, a diagnosis of neurally mediated syncope, the most frequent cause of syncope in the young, is often erroneously made. Clinical clues suggest that syncope has an arrhythmic rather than a neurally mediated origin. In addition, the presence of premature ventricular contractions on an electrocardiogram recorded shortly after a syncopal event has utmost importance in establishing the cause of syncope. Although such extrasystoles are frequently benign, especially when associated with a long coupling interval, they also may suggest a malignant origin when closely coupled to the preceding complex with short coupling intervals (usually <350 ms). These arrhythmias mainly originate from the Purkinje system (usually the right ventricle in men and the left ventricle in women) and favorably respond to quinidine as well as to ablation therapy targeting Purkinje-fibers ectopic activity.

Clinical characteristics, therapy and long-term outcome of short-coupled idiopathic ventricular fibrillation. A systematic review of published case reports with new extended long-term follow-up

Funding Acknowledgements

Type of funding sources: None.

Background

Short-coupled idiopathic ventricular fibrillation (SC-IVF) is a rare, potentially lethal arrhythmia, initiated by SC-PVCs. Only small series have been published.

Purpose

To assess the clinical characteristics, therapies and long-term outcomes of patients (pts) with SC-IVF.

Methods

Data from all published case reports on SC-IVF/Polymorphic VT were collected. Inclusion criteria were normal cardiac work-up including during follow-up (FU), and documented SC-PVC-VF available for our analysis and ruling out early repolarization syndromes and CPVT at VF onset. Updated information was provided by 82% of authors contacted, with 22 additional ECG tracings provided.

Results

A total of 100 pts’ cases were identified, including 82 who met inclusion criteria. Mean FU increased from 2.75+3.6 years in the original publications to 10.5+7.9 years (p&lt;0.0001). There were 42 (51%) males, aged 39.6+13.5 years at the time of SC-IVF diagnosis. Pts presented with syncope (40%), aborted cardiac arrest (ACA) (16%), ACA + arrhythmic storm (13%), arrhythmic storm (10%), ICD shocks (8%) or palpitations (1%). Prior history included syncope in 32 (39%) pts. Mean coupling interval of the SC-PVC was 293.6+50.7ms. Presumed sites of PVC origin were the RV, LV and RVOT in 54%, 21% and 5% of pts, respectively. A total of 69 (84%) pts had an ICD implanted before or after SC-IVF documentation. During long-term treatment with quinidine (n=11) or verapamil (n=32), SC-IVF did not recur in 82% and 50% of pts, respectively (p=0.08). Ablation was performed in 43 (92%) of the 47 pts in whom it was attempted. Ablation sites were the Purkinje RV (43%) or LV (23%), and the non-Purkinje RV (19%) or LV (2%). Acute and late success rates after a first ablation were 83% and 61.7%, respectively. A second ablation in 7 pts yielded a 74.5% total success rate. No difference was found in the success rate of quinidine compared with ablation procedures (p=0.6). During FU, 4 pts died including 2 from sudden cardiac death; both pts were treated with verapamil and refused ICD implantation or replacement.

Conclusion

SC-IVF mainly presents following syncope. Quinidine and ablation procedures have comparable long-term high efficacy in arrhythmia control. The commonest sites of successful ablation are the RV and LV Purkinje fibers.

Short-Coupled Idiopathic Ventricular Fibrillation: A Literature Review With Extended Follow-Up

Idiopathic ventricular fibrillation is responsible for approximately 10% of cases of aborted cardiac arrest. Recent studies have shown that short-coupled ventricular premature complexes are present at the onset of idiopathic ventricular fibrillation in 6.6%-17% of patients. The present review provided information on 86 patients with short-coupled malignant ventricular arrhythmias that were reported as case reports or small patient series during the last 70 years. In 75% of the 81 cases published during the last 40 years, extended information and follow-up (from 2.63 ± 4.5 to 10.67 ± 7.8 years; P < 0.001, between the original publication to the latest update) could be obtained from the authors. The review shows that short-coupled malignant ventricular arrhythmias occurred almost equally in males and females, at the mean age of 40 years. A tendency for later occurrence of the arrhythmia by 4 years was observed in females. A prior history of syncope was noted in 45.3% of the patients, whereas arrhythmic storm occurred in 42% at presentation. The most common mode of revelation of short-coupled malignant ventricular arrhythmias was syncope (53.5%), followed by aborted cardiac arrest (26.7%) and recurrent arrhythmic event after prior implantable-cardioverter defibrillator implantation for idiopathic ventricular fibrillation (17.4%). For the first time, short-coupled malignant arrhythmias exhibiting "not-so-short" coupling intervals (≥350 ms) were found in a significant proportion of patients (17.4%). During long-term follow-up, quinidine yielded a slightly higher success rate in arrhythmia control than ablation. Larger studies are necessary to assess the best strategy for the management of this potentially lethal arrhythmia.

Implantation of cardiac electronic devices in active COVID-19 patients: Results from an international survey

BACKGROUND

Cardiac implantable electronic device (CIED) implantation rates as well as the clinical and procedural characteristics and outcomes in patients with known active coronavirus disease 2019 (COVID-19) are unknown.

OBJECTIVE

The purpose of this study was to gather information regarding CIED procedures during active COVID-19, performed with personal protective equipment, based on an international survey.

METHODS

Fifty-three centers from 13 countries across 4 continents provided information on 166 patients with known active COVID-19 who underwent a CIED procedure.

RESULTS

The CIED procedure rate in 133,655 hospitalized COVID-19 patients ranged from 0 to 16.2 per 1000 patients (P <.001). Most devices were implanted due to high-degree/complete atrioventricular block (112 [67.5%]) or sick sinus syndrome (31 [18.7%]). Of the 166 patients in the study survey, the 30-day complication rate was 13.9% and the 180-day mortality rate was 9.6%. One patient had a fatal outcome as a direct result of the procedure. Differences in patient and procedural characteristics and outcomes were found between Europe and North America. An older population (76.6 vs 66 years; P <.001) with a nonsignificant higher complication rate (16.5% vs 7.7%; P = .2) was observed in Europe vs North America, whereas higher rates of critically ill patients (33.3% vs 3.3%; P <.001) and mortality (26.9% vs 5%; P = .002) were observed in North America vs Europe.

CONCLUSION

CIED procedure rates during known active COVID-19 disease varied greatly, from 0 to 16.2 per 1000 hospitalized COVID-19 patients worldwide. Patients with active COVID-19 infection who underwent CIED implantation had high complication and mortality rates. Operators should take these risks into consideration before proceeding with CIED implantation in active COVID-19 patients.

Genotype-Phenotype Correlation of SCN5A Genotype in Patients With Brugada Syndrome and Arrhythmic Events: Insights From the SABRUS in 392 Probands

BACKGROUND

Brugada syndrome (BrS) is associated with mutations in the cardiac sodium channel gene, SCN5A. However, genetic studies of patients with BrS with arrhythmic events have been limited. We sought to compare various clinical, ECG, and electrophysiological parameters according to SCN5A genotype in a large cohort of BrS probands with first arrhythmic event.

METHODS

Survey on Arrhythmic Events in Brugada Syndrome is a survey of 10 Western and 4 Asian countries, gathering 678 patients with BrS with first arrhythmic event. Only probands were included, and SCN5A genotype adjudicated. Patients without appropriate genetic data were excluded. Associations of genotype with clinical features were analyzed.

RESULTS

The study group comprised 392 probands: 92 (23.5%) SCN5A+(44 pathogenic/likely pathogenic [P/LP] and 48 variants of unknown significance) and 300 (76.5%) SCN5A-.SCN5A missense variants and the patients hosting them were similar regardless of adjudication. A higher proportion of patients with P/LP were pediatric (<16 years) compared with SCN5A- (11.4% versus 3%, P=0.023). The proportion of females was higher among patients with P/LP compared with SCN5A- (18.2% versus 6.3%, P=0.013). P/LP probands were more likely to have a family history of sudden cardiac death compared with SCN5A- (41.9% versus 16.8%, P<0.001). A higher proportion of patients with P/LP were White compared with SCN5A- (87.5% versus 47%, P<0.001). Ethnicity (odds ratio, 5.41 [2.8-11.19], P<0.001) and family history of sudden cardiac death (odds ratio, 2.73 [1.28-5.82], P=0.009) were independent variables associated with P/LP genotype following logistic regression.

CONCLUSIONS

The genetic basis of BrS has a complex relationship with gender, ethnicity, and age. Probands hosting a P/LP variant tended to experience their first arrhythmic event at a younger age and to have events triggered by fever compared with patients with SCN5A-. In addition, they were more likely to be White and to have family history of sudden cardiac death. Among females, a P/LP variant suggests an increased risk of being symptomatic. This association should be further studied on an ethnically specific basis in large prospectively collected international cohorts.

The prevalence of left and right bundle branch block morphology ventricular tachycardia amongst patients with arrhythmogenic cardiomyopathy and sustained ventricular tachycardia: insights from the European Survey on Arrhythmogenic Cardiomyopathy

AIMS

In arrhythmogenic cardiomyopathy (ACM), sustained ventricular tachycardia (VT) typically displays a left bundle branch block (LBBB) morphology while a right bundle branch block (RBBB) morphology is rare. The present study assesses the VT morphology in ACM patients with sustained VT and their clinical and genetic characteristics.

METHODS AND RESULTS

Twenty-six centres from 11 European countries provided information on 954 ACM patients who had ≥1 episode of sustained VT spontaneously documented during patients' clinical course. Arrhythmogenic cardiomyopathy was defined according to the 2010 Task Force Criteria, and VT morphology according to the QRS pattern in V1. Overall, 882 (92.5%) patients displayed LBBB-VT alone and 72 (7.5%) RBBB-VT [alone in 42 (4.4%) or in combination with LBBB-VT in 30 (3.1%)]. Male sex prevalence was 79.3%, 88.1%, and 56.7% in the LBBB-VT, RBBB-VT, and LBBB + RBBB-VT groups, respectively (P = 0.007). First RBBB-VT occurred 5 years after the first LBBB-VT (46.5 ± 14.4 vs 41.1 ± 15.8 years, P = 0.011). An implanted cardioverter-defibrillator was more frequently implanted in the RBBB-VT (92.9%) and the LBBB + RBBB-VT groups (90%) than in the LBBB-VT group (68.1%) (P < 0.001). Mutations in PKP2 predominated in the LBBB-VT (65.2%) and the LBBB + RBBB-VT (41.7%) groups while DSP mutations predominated in the RBBB-VT group (45.5%). By multivariable analysis, female sex was associated with LBBB + RBBB-VT (P = 0.011) while DSP mutations were associated with RBBB-VT (P < 0.001). After a median follow-up of 103 (51-185) months, death occurred in 106 (11.1%) patients with no intergroup difference (P = 0.176).

CONCLUSION

RBBB-VT accounts for a significant proportion of sustained VTs in ACM. Sex and type of pathogenic mutations were associated with VT type, female sex with LBBB + RBBB-VT, and DSP mutation with RBBB-VT.

Asymptomatic Athlete With Short-Coupled Premature Ventricular Contractions

We present an asymptomatic 26-year-old athlete, with no family history of sudden cardiac death and no structural heart disease, who displayed short-coupled premature ventricular contractions on exercise test and Holter monitoring. The rarity of the case as well as management dilemmas are discussed. (Level of Difficulty: Intermediate.)

Arrhythmias Utilizing Concealed Nodoventricular or His-Ventricular Pathways: A Structured Approach to Diagnosis and Management

OBJECTIVES

This study sought to describe the electrophysiologic characteristics, diagnostic maneuvers, and treatment of a series of arrhythmias using concealed nodoventricular (cNV) or His-ventricular (cHV) pathways.

BACKGROUND

Confirming the presence and participation of cNV or cHV pathways in tachyarrhythmias is challenging.

METHODS

We present 4 cases of tachycardias with a participatory cNV or cHV pathway.

RESULTS

The first patient had a narrow complex tachycardia with ventriculoatrial dissociation. Findings of an entrainment pacing from the right ventricle and fused premature ventricular complexes suggested cNV pathway involvement. The second patient had nonsustained narrow complex tachycardia with more ventricular than atrial complexes. The tachycardia exhibited an anterograde His-right bundle (RB) activation sequence and normal His-ventricular (HV) interval and consistently terminated with fused ventricular extra stimuli, suggesting cNV pathway participation. The third patient had a wide complex tachycardia (WCT) with either a right or left bundle branch block pattern. The WCT showed an eccentric His-RB activation sequence and short HV interval and terminated with fused premature ventricular complexes, suggesting a cHV (or concealed fasciculoventricular) pathway involvement. The fourth patient had a WCT with alternating bundle branch block morphologies with a short HV interval. Entrainment from the basal right ventricle demonstrated fusion and a short postpacing interval, suggesting cHV (or fasciculoventricular) pathway involvement. Ablation at the proximal RB rendered the tachycardia noninducible.

CONCLUSIONS

A structured approach can help diagnose and treat cNV or cHV pathways. We emphasize the importance of evaluating both the His-RB activation pattern and HV interval during sinus rhythm and tachycardia as well as the ventricular pacing study.

Out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation in patients with normal electrocardiograms: results from a multicentre long-term registry

AIMS 

To define the clinical characteristics and long-term clinical outcomes of a large cohort of patients with idiopathic ventricular fibrillation (IVF) and normal 12-lead electrocardiograms (ECGs).

METHODS AND RESULTS

Patients with ventricular fibrillation as the presenting rhythm, normal baseline, and follow-up ECGs with no signs of cardiac channelopathy including early repolarization or atrioventricular conduction abnormalities, and without structural heart disease were included in a registry. A total of 245 patients (median age: 38 years; males 59%) were recruited from 25 centres. An implantable cardioverter-defibrillator (ICD) was implanted in 226 patients (92%), while 18 patients (8%) were treated with drug therapy only. Over a median follow-up of 63 months (interquartile range: 25-110 months), 12 patients died (5%); in four of them (1.6%) the lethal event was of cardiac origin. Patients treated with antiarrhythmic drugs only had a higher rate of cardiovascular death compared to patients who received an ICD (16% vs. 0.4%, P = 0.001). Fifty-two patients (21%) experienced an arrhythmic recurrence. Age ≤16 years at the time of the first ventricular arrhythmia was the only predictor of arrhythmic recurrence on multivariable analysis [hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.18-0.92; P = 0.03].

CONCLUSION 

Patients with IVF and persistently normal ECGs frequently have arrhythmic recurrences, but a good prognosis when treated with an ICD. Children are a category of IVF patients at higher risk of arrhythmic recurrences.

Complex Re-Entrant Arrhythmias Involving the His-Purkinje System: A Structured Approach to Diagnosis and Management

OBJECTIVES

This study sought to characterize the presentations, electrophysiological features and diagnostic maneuvers for a series of unique arrhythmias involving the HPS.

BACKGROUND

By virtue of its unique anatomy and ion channel composition, the His-Purkinje system (HPS) is prone to a variety of arrhythmic perturbations.

METHODS

The authors present a collaborative multicenter case series of 6 patients with HPS-related arrhythmias. All patients underwent electrophysiological studies using standard multipolar catheters.

RESULTS

In 3 patients, both typical and reverse bundle branch re-entry were seen, with 1 patient demonstrating "figure of 8" re-entry likely involving the septal fascicle. One patient presented with systolic dysfunction associated with a high premature ventricular complex burden, with the mechanism being bundle-to-bundle re-entrant beats masquerading as dual response to a single sinus impulse. Two patients were diagnosed with interfascicular re-entry. Diagnosis was aided by careful assessment of HV interval in sinus rhythm and ventricular tachycardia, multipolar catheters to assess the activation sequence of the His-right bundle branch, and fascicles and entrainment of different components of the HPS. Cure of the arrhythmia was achieved by ablation of the right bundle branch block in 3 patients, the left septal fascicle in 2 patients, and the left posterior fascicle in 1 patient.

CONCLUSIONS

Proper diagnosis of re-entrant arrhythmias involving the HPS may prove challenging. We emphasize a structured approach for diagnosis and effective therapy.

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

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 &gt;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

Use of Electrophysiological Studies in Transcatheter Aortic Valve Implantation

New conduction disturbances requiring permanent pacemaker implantation remain common complications following transcatheter aortic valve implantation (TAVI). It has been suggested that electrophysiological studies could help identify patients who will require permanent pacemaker implantation after TAVI. This article summarises contemporary data on the use of electrophysiological studies in patients undergoing TAVI.

A case report of arrhythmogenic ventricular cardiomyopathy presenting with sustained ventricular tachycardia arising from the right and the left ventricles before structural changes are documented

Background

Arrhythmogenic ventricular cardiomyopathy (AC) is a genetic progressive disease characterized by fibro-fatty replacement of either ventricles in isolation or in combination. Arrhythmogenic ventricular cardiomyopathy is frequently associated with ventricular tachycardia (VT) having a left bundle branch block (LBBB) morphology and much more rarely with VT having right bundle branch block (RBBB) morphology even when the left ventricle is involved. Cardiac magnetic resonance (CMR) imaging plays a key role in the diagnosis of AC. Sustained VT in AC may occur in the concealed stage of the disease before the manifestation of morphological abnormalities on echocardiogram; however, they almost always are accompanied by structural abnormalities of the ventricles on CMR.

Case summary

A 54-year-old man presented with sustained VT of LBBB configuration consistent with the diagnosis of AC but with no right ventricular (RV) anomalies at repeat CMR. Ten years later, he developed sustained VT with RBBB morphology and structural changes at CMR compatible with RV involvement in the setting of AC. Two years later, he suffered from recurrent identical sustained RBBB-VT with typical CMR signs of left ventricular involvement. Genetic analysis was negative for any known mutation.

Discussion

In the present report, we describe a patient with AC who first exhibited LBBB- and 10 years later RBBB-sustained VT. Contrasting with what is usually observed in patients with AC, documentations of the VT's arising from either ventricle were found to precede the structural anomalies in the respective cardiac chambers. This case highlights that normal CMR does not exclude underlying AC contrary to the perceptions of many clinicians. In addition, it strongly encourages repeating CMR after 1-2 years when the diagnosis of AC is highly suspected.

Quinidine-responsive out-of-hospital polymorphic ventricular tachycardia in patients with coronary heart disease

Aims

We recently reported that patients with coronary artery disease (CAD) who develop polymorphic ventricular tachycardia (VT) during the healing phase of an acute coronary event, generally fail to respond to revascularization or standard antiarrhythmic therapy but respond immediately to quinidine therapy. Here, we describe that CAD patients presenting with out-of-hospital polymorphic VT without a recent coronary event or an obvious precipitating factor, also respond uniquely to quinidine therapy.

Methods and results

Retrospective study of patients with unheralded, mainly out-of-hospital, polymorphic VT related to CAD but without evidence of acute myocardial ischaemia. We identified 20 patients who developed polymorphic VT without precipitating factors. The polymorphic VT events were triggered by extrasystoles with short (376 ± 49 ms) coupling interval. Arrhythmic storms occurred in 70% patients. These arrhythmic storms were generally refractory to conventional antiarrhythmic therapy but invariably responded to quinidine therapy. Revascularization was antiarrhythmic in 3 patients despite the absent clinical or ECG signs of ischaemia. During long-term follow-up (range 2 months to 11 years), 3 (15%) of patients not receiving quinidine developed recurrent polymorphic VT. There were no recurrent arrhythmias during long-term quinidine therapy.

Conclusions

Patients with CAD may develop polymorphic VT in the absence of obvious acute ischaemia or apparent precipitating factors, presenting as out-of-hospital polymorphic VT with high risk of arrhythmic storms that respond uniquely to quinidine therapy.

Characterization and Management of Arrhythmic Events in Young Patients With Brugada Syndrome

BACKGROUND

Information on young patients with Brugada syndrome (BrS) and arrhythmic events (AEs) is limited.

OBJECTIVES

The purpose of this study was to describe their characteristics and management as well as risk factors for AE recurrence.

METHODS

A total of 57 patients (age ≤20 years), all with BrS and AEs, were divided into pediatric (age ≤12 years; n = 26) and adolescents (age 13 to 20 years; n = 31).

RESULTS

Patients' median age at time of first AE was 14 years, with a majority of males (74%), Caucasians (70%), and probands (79%) who presented as aborted cardiac arrest (84%). A significant proportion of patients (28%) exhibited fever-related AE. Family history of sudden cardiac death (SCD), prior syncope, spontaneous type 1 Brugada electrocardiogram (ECG), inducible ventricular fibrillation at electrophysiological study, and SCN5A mutations were present in 26%, 49%, 65%, 28%, and 58% of patients, respectively. The pediatric group differed from the adolescents, with a greater proportion of females, Caucasians, fever-related AEs, and spontaneous type-1 ECG. During follow-up, 68% of pediatric and 64% of adolescents had recurrent AE, with median time of 9.9 and 27.0 months, respectively. Approximately one-third of recurrent AEs occurred on quinidine therapy, and among the pediatric group, 60% of recurrent AEs were fever-related. Risk factors for recurrent AE included sinus node dysfunction, atrial arrhythmias, intraventricular conduction delay, or large S-wave on ECG lead I in the pediatric group and the presence of SCN5A mutation among adolescents.

CONCLUSIONS

Young BrS patients with AE represent a very arrhythmogenic group. Current management after first arrhythmia episode is associated with high recurrence rate. Alternative therapies, besides defibrillator implantation, should be considered.

New Insights on Verapamil-Sensitive Idiopathic Left Fascicular Tachycardia

Verapamil-sensitive left fascicular monomorphic ventricular tachycardia (LF-VT) was first described ~4 decades ago. Our knowledge regarding this arrhythmia is evolving continuously. The current review aims to highlight up to date aspects of this arrhythmia focusing on its ECG recognition, new considerations of the reentrant circuit, ablation targets in inducible and non-inducible patients and the approach to LF-VT with multiform morphology.