Pre-excitation Pattern Research Articles

Successful elimination of double accessory pathways: a rare case of co-existence between right inferoseptal WPW and left lateral AVRT

Background: Managing double accessory pathways (APs) in the clinical setting presents significant challenges, primarily due to the rarity of this condition and the complexities involved in both diagnosis and treatment. Case Presentation: A 51-year-old male presented with recurrent episodes of palpitation. Electrocardiography (ECG) revealed a sinus rhythm with a pre-excitation pattern that was characterized by a delta wave morphology. This pattern showed a negative deflection in V1, a transitional zone in V2, and negativity in lead III and aVF, which indicated an accessory pathway through the right infero-septal pathway. Further evaluation with electrophysiology study (EPS) confirmed the presence of accessory pathways, with the right infero-septal pathway exhibiting pre-excitation during sinus rhythm. Radiofrequency ablation (RFA) successfully eliminated the right infero-septal accessory pathway. Subsequently, coronary sinus propagation shifted from a concentric to an eccentric pattern, indicating another accessory pathway from the left lateral region. Another mapping was performed retrogradely at the mitral annulus, revealing ventriculoatrial (VA) fusion at the left lateral area and demonstrating inducible atrioventricular reentrant tachycardia (AVRT). RFA successfully eliminated the left lateral accessory pathway, resulting retrograde block. Conclusion: This case highlights the importance of thorough diagnostics and tailored treatment strategies in managing dual APs, emphasizing the effectiveness of EPS-guided RFA for complex arrhythmias. Keyword: atrioventricular reentrant tachycardia, double accessory pathway, radiofrequency ablation, wolf-parkinson-white syndrome

Atypical Pre-excitation Pattern in Asymptomatic Wolff-Parkinson-White—A Hallmark for High Risk?

Abstract Introduction Delta wave morphology during sinus rhythm on 12 lead ECG usually allows for a relatively precise prediction of the anatomic location of an accessory pathway (AP) provided that the rhythm is fully pre-excited. However, the pre-excitation pattern during sinus rhythm usually offers little information about sudden cardiac death (SCD) risk in adult patients with asymptomatic Wolf-Parkinson-White (WPW). Case Presentation A 42-year-old policeman was referred for an asymptomatic WPW pattern with an unusual delta wave. Initial mapping showed that atrio-ventricular (A-V) fusion on the lateral mitral annulus and radiofrequency (RF) ablation induced a shift in the pre-excitation pattern. Re-mapping identified A-V fusion on the left postero-septal area. Another RF application eliminated pre-excitation. Re-mapping identified A-V fusion on the postero-septal aspect of the mitral annulus and another RF application almost instantaneously induced an A-V split and loss of pre-excitation. Post-ablation testing proved normal anterograde A-V conduction without pre-excitation and no ventriculo-atrial conduction. Serial ECGs proved the persistent loss of pre-excitation at one-month of follow-up. Conclusion This case highlights the diagnostic challenges associated with atypical pre-excitation patterns and the importance of a thorough evaluation in asymptomatic individuals. Patients with atypical pre-excitation may harbor multiple accessory pathways (MAPs) and should be carefully assessed to mitigate the risk of SCD.

Utility of Right-Electrocardiogram Chest Leads in Localization of Accessory Pathways in Patients with Wolf-Parkinson-White Syndrome

Abstract Background Prediction of the precise location of an Accessory Pathway (AP) prior to the ablation procedure is of clinical importance. Several algorithms have been published to localize the AP on a surface 12-lead electrocardiogram (ECG). Most of them are based on analysis of delta wave morphology or QRS polarity. However, they are somewhat complicated, and an accurate determination of the delta wave morphology or QRS polarity are occasionally difficult, and their accuracy are still limited. Recently a new published algorithm using right-sided ECG chest leads for the prediction site of an AP is figured out and still under study for measuring its accuracy. Aim of the Work The aim of this study is to evaluate the accuracy of the utility of rightsided ECG Chest leads in the localization of APs in patients with manifest pre-excitation pattern in 12-lead ECG in prospective manner. Patients and Methods This study included 35 patients in whom successful ablation of manifest Wolff-Parkinson-White (WPW) syndrome was performed in prospective manner. Standard 12-lead ECG and right-sided chest ECG waveforms were recorded before the procedure. Results There were 13, 10, and 12 patients with left, right, and septal APs, respectively. All left AP patients had type A (RS morphology) in V1 and 12 of them in V4R leads, only 1 had type B in V4R lead. Of the 10 right AP patients, 5 had type B (rS morphology) in V1 while all 10 patients had type B in V4R. Of the 12 septal AP patients, 9 had type C (QS or Qr morphology) in V1, while 2 of the 12 patients had type B, and 1 of 12 patients had type A. All the 12 septal AP patients had type C in V4R. Conclusions The QRS morphology of V1 and V4R leads could predict the site of AP in patients with WPW syndrome with overall accuracy of 85.7% and 98%, respectively. Abbreviations AP: Accessory Pathway; ECG: Electrocardiogram; EPS: Electrophysiology study; RF: Radiofrequency; WPW: Wolff-Parkinson-White

Electrocardiographic patterns of ventricular pre-excitation in dogs with right-sided accessory pathways.

The aim of the study was to describe the electrocardiographic features of ventricular pre-excitation (VPE) patterns characterized by the presence of delta (δ) wave, short P-δQRS interval, wide δQRS complexes in dogs with right-sided accessory pathways. Twenty-six dogs with a confirmed accessory pathways (AP) via electrophysiological mapping were included. All dogs underwent a complete physical examination, 12-lead ECG, thoracic radiography, echocardiographic examination and electrophysiologic mapping. The AP were located in the following regions: right anterior, right posteroseptal, right posterior. The following parameters were determined: P-δQRS interval, δQRS duration, δQRS axis, δQRS morphology, δ-wave polarity, Q-wave, R-wave, R'-wave, S-wave amplitude, and R/S ratio. In lead II, the median δQRS complex duration was 82.4 (IQR 7.2) and the median P-δQRS interval duration was 54.6 (IQR 4.2) msec. The median δQRS complex axis in the frontal plane was: + 68° (IQR 52.5) for right anterior APs, - 24 ° (IQR 24) for right postero-septal APs, - 43.5 ° (IQR 27.25) for right posterior APs (P = 0.007). In lead II, the polarity of the δ wave was positive in 5/5 right anterior APs and negative in 7/11 postero-septal APs and 8/10 in right posterior APs. In precordial leads of all dogs, R/S was ≤ 1 in V1 and > 1 in all leads from V2 to V6. Surface electrocardiogram can be used to distinguish right anterior APs from right posterior and right postero-septal ahead of an invasive electrophysiological study.

Abstract 14091: Severe Hypothyroidism Revealing Hidden Tracts

Discussion: Atrioventricular reciprocating tachycardia (AVRT) is a type of Supraventricular tachycardia (SVT) caused by an accessory pathway can result in symptomatic and also life-threatening arrhythmias. Supraventricular tachycardias are less commonly seen in hypothyroidism than hyperthyroidism. We present a case of a 41 year old gentleman who presented with chest pain and SVT was found to have severe hypothyroidism with pre-excitation pattern on his EKG. Case: 41-year-old Caucasian gentleman with history of untreated Hashimoto’s thyroiditis presented with palpitations and acute onset left-sided chest pain. His symptoms were aggravated with movement and improved with rest. When EMS found him, his vitals were significant for tachycardia with a heart rate (HR) of 200 beats per minute (bpm). EKG showed supraventricular tachycardia. Vagal maneuvers were attempted followed by adenosine. This resulted in conversion to sinus rhythm and improvement in HR to 88 bpm. His chest pain completely resolved. He was then brought to the emergency room where he had normal vitals. Examination revealed thyroid gland was palpable and noted to be diffusely enlarged. Laboratory data was significant for an elevated thyroid-stimulating hormone (TSH) of 373 mIU/ml and undetectable free thyroxine (fT4) levels. His creatinine kinase (CK) was high at 16260, and troponin was elevated at 0.220 ng/ml (reference:<0.04 ng/ml). TPO antibodies were >600 IU/ml. EKG demonstrated sinus rhythm with pre-excitation and incomplete left bundle-branch block. He had normal chest x-ray. An echocardiogram showed an ejection fraction of 55% with mild LV diastolic dysfunction. He later underwent a stress myocardial perfusion scan which showed no definite evidence of inducible ischemia. Follow up: He was started on thyroxine replacement therapy. He is due for an EP study to evaluate for an accessory pathway causing pre-excitation with repolarization pattern on his ECG. Conclusion: This case suggests that severe hypothyroidism can also cause supraventricular tachycardias (SVT) by metabolic and conduction derangements revealing concealed bypass tracts in patients with accessory pathways. In most cases these arrhythmias are reversible once the underlying thyroid disorder is treated.

Shortened PQ interval in the differential diagnosis of Anderson-Fabry disease: a case report

In this article, we present a case of a patient with a late diagnosis of Fabry disease caused by a pathogenic variant in the GLA gene (p.1287_1288dup), who repeatedly attempted interventional treatment of Wolff-Parkinson-White Syndrome due to characteristic electrocardiographic pattern of ventricular preexcitation and paroxysmal arrhythmias. The proposed pathognomonic signs of the disease will ensure timely diagnosis and the appointment of specific treatment.

INTERMITTENT WOLFF-PARKINSON-WHITE SYNDROME: A CASE REPORT WITH LITERATURE REVIEW

TOPIC: Cardiovascular Disease TYPE: Medical Student/Resident Case Reports INTRODUCTION: An uncommon form of cardiac preexcitation, Wolff-Parkinson-White (WPW) syndrome results in an abnormal QRS complex that is generated as a result of normal conduction over the atrioventricular conduction pathway in conjunction with the accessory conduction pathway. WPW is classically characterized by the presence of short P-R interval (<120 ms), widened QRS interval (>110 ms) with slurred upstroke known as the delta wave on EKG and symptomatic tachycardia(1). Among patients in the United States less than 50 years of age there is a prevalence of 0.36/1000(2). Intermittent preexcitation in WPW is described as the loss of delta waves with prolongation of the P-R interval. The following case report presents a rare form of intermittent preexcitation with WPW syndrome. CASE PRESENTATION: A healthy 34-year-old man presented with a complaint of 1-2 episodes per week of palpitations, each lasting a few seconds. Initial EKG was remarkable for classic findings of WPW syndrome. His cardiac workup was relatively unremarkable, except for the exercise stress test which showed the disappearance of delta waves with HR >144 bpm in Stage 4 of the Bruce protocol. Serial EKGs revealed a pattern of intermittent preexcitation with WPW syndrome. DISCUSSION: Individuals with intermittent preexcitation may have a longer refractory period of the accessory pathway with poor conduction(3). Such unpredictable conduction in intermittent preexcitation via the accessory pathway is clinically relevant in asymptomatic to minimally symptomatic patients. The accessory pathway of WPW syndrome is also associated with reentrant supraventricular tachycardia and sudden cardiac death depending on the characteristics of conduction across the accessory pathway. Current treatment guidelines for WPW syndrome with intermittent preexcitation recommends no intervention in asymptomatic patients with an unremarkable diagnostic workup. With persistent preexcitation, pharmacologic therapy to slow the ventricular heart rate or to prevent the arrhythmia and the non-pharmacological therapy of catheter ablation of the accessory pathway are available. CONCLUSIONS: Cases of WPW syndrome with intermittent preexcitation range from asymptomatic to life-threatening. Such cases dictate careful review of electrocardiograms and close monitoring with ambulatory follow-ups. This case with low-risk features exemplifies the lack of need for further invasive testing in asymptomatic clinical scenarios of WPW syndrome with intermittent preexcitation. REFERENCE #1: 1. Iqbal AM, Ghazni MS, Mubarik A, Zubair N, Jamal SF. The Conversion of Wolff-Parkinson-White (WPW) Pattern into WPW Syndrome in the Presence of Ischemia: A Case Report. Cureus. 2019;11(2):e4147. Published 2019 Feb 27. doi:10.7759/cureus.4147 REFERENCE #2: 2. Lu CW, Wu MH, Chen HC, Kao FY, Huang SK. Epidemiological profile of Wolff-Parkinson-White syndrome in a general population younger than 50 years of age in an era of radiofrequency catheter ablation. Int J Cardiol. 2014;174(3):530-534. doi:10.1016/j.ijcard.2014.04.134 REFERENCE #3: 3. Klein GJ, Gulamhusein SS. Intermittent preexcitation in the Wolff-Parkinson-White syndrome. The American Journal of Cardiology. 1983 Aug;52(3):292-296. DOI: 10.1016/0002-9149(83)90125-x. DISCLOSURES: No relevant relationships by Ajay Agarwal, source=Web Response No relevant relationships by Akruti Patel, source=Web Response

Assessing and Managing Asymptomatic Ventricular Preexcitation in the Young Athlete

Assessing and Managing Asymptomatic Ventricular Preexcitation in the Young Athlete

Charge Syndrome Hallmarked with Wolff-Parkinson-White Syndrome and Patent Ductus Arteriosus; 20 Years Post-Repairing; An Extreme Combination

Rationale: CHARGE syndrome or Hall-Hittner syndrome is a pleiotropic disorder, in which the name is derived from the abbreviation epitomizing its six clinical criteria: ocular coloboma, cardiac defects, choanal atresia, growth or developmental retardation, genital hypoplasia, and ear anomalies or deafness. Wolff-Parkinson-White syndrome is the most frequent pattern of ventricular pre-excitation. Patent ductus arteriosus is one of the most frequent congenital heart diseases due to failure of closure of the ductus arteriosus within 72 hours of birth. CHARGE syndrome, Wolff-Parkinson-White syndrome, and patent ductus arteriosus are so difficult to be present in a single entity. Patient concerns: A young female girl patient presented to the physician’s outpatient clinic with acute confusion status with a past repaired patent ductus arteriosus. Diagnosis: CHARGE syndrome hallmarked with Wolff-Parkinson-White syndrome and patent ductus arteriosus; 20 years post-repairing. Interventions: Plain chest x-ray, electrocardiography, oxygenation, and echocardiography. Outcomes: A dramatic clinical improvement post-oxygenation had happened. Lessons: CHARGE syndrome with Wolff-Parkinson-White syndrome and repaired patent ductus arteriosus is an extreme combination. The existence of infantile electrocardiographic Tee-Pee sign of hypocalcemia and adult low ionized calcium with CHARGE syndrome is highly suggestive of associated DiGeorge phenotype syndrome. An absence of tachycardia post- repairing of patent ductus arteriosus from 11 mo until the 20th-year-old is a good prognostic sign. The presence of an infantile T-wave alternance will strengthen both the risk of serious arrhythmia and the efficacy of patent ductus arteriosus repairing.

Non-algorithmic approach to accessory pathway localization based on a mobile app

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Polish Cardiac Society - Section of Non-invasive Electrocardiology and Telemonitoring (PTK SENIT) Background. Electrocardiographical localization of accessory pathways (AP) in WPW syndrome remains an elusive goal. Despite several, often very complex algorithms that were developed over the last three decades, none of them is very accurate - as demonstrated by several independent validation studies. Moreover, algorithms are difficult to remember, which further limits their usefulness. The accessory pathway regions are arbitrary and transitions between them are smooth, not binary. The same applies to ECG features such as QRS polarity – they are not binary. Moreover, even the most careful ECG lead placement cannot compensate for the variability in heart position within the chest. Therefore, it is unrealistic to expect that any ECG feature or feature set will precisely identify a particular location in a 0 vs. 1 fashion. Aim We intend to create a mobile app / web based localizing application, that would support a novel method for AP localization: a colour density map generator - based on actual distribution of a sizable number of accessory pathway with a particular QRS features. Methods A total of 881 consecutive AP ablation procedures were reviewed and patients with successful ablation of an overt accessory pathway were included. ECG with baseline and full preexcitation obtained during incremental atrial pacing were obtained. AP localization was based on stored fluoroscopic images in several projections and procedure description. Each AP localization, as well as QRS polarity in all 12 leads, separately for full and baseline preexcitation patterns, were coded and introduced into the application database. An application web-based, optimized for mobile devices was developed. This application enabled to graphically show changing localization of AP with regard to the introduced, at each step, QRS polarity in a particular ECG lead. User can choose his/her own steps or criteria; there is no need to adhere to the proposed steps. Results A total of 604 patients/ ECGs were available for density map generation. With each additional lead QRS information introduced into the application the user can appreciate more and more precise localization of the AP. This quickly enables to pinpoint the area of maximum probability, i.e. the most likely/frequent location, followed by the immediate adjacent locations. Representative screen shots of to typical inital steps for left- and right-sided APs are provided below (Figure 1 and Figure 2). Limited prospective assessment was very favourable. Conclusions A novel method, easy to use, not requiring to remember any algorithmic steps, and based on an analysis of by far the largest cohort of over accessory pathways (in comparison with published algorithms) was developed. Prospective validation of the localization application seems warranted. Abstract Figure.

Beck's Quadrad? A Rare Case of Pericardial Tamponade Presenting as Transient Pre-Excitation Early after Cardiac Transplantation

<h3>Introduction</h3> Cardiac tamponade is a potentially fatal complication after cardiac surgery. An acute accumulation of fluid generally presents as Beck's triad, however, a slowly accumulating pericardial effusion can have variable clinical presentations. We report a case of transient pre-excitation on post-operative electrocardiogram (ECG) after cardiac transplantation with resolution of aberrant conduction following pericardiocentesis for cardiac tamponade. <h3>Case Report</h3> A 46-year-old African American male with NICM HFrEF (EF 18%) presented in cardiogenic shock, COVID pneumonia requiring milrinone infusion and intra-aortic balloon pump support for stabilization. After clearance of his viral replicon, he underwent orthotopic heart transplantation. His postoperative course was complicated by monomorphic non-sustained ventricular tachycardia. His ECGs revealed a right bundle branch block with prominent delta waves concerning for pre-excitation through an accessory pathway. Electrophysiology was consulted and confirmed an accessory pathway localized to the right superior paraseptal region. He subsequently developed atrial fibrillation and his mean blood pressure dropped from 80 to 60mmHg. A bedside echocardiogram showed a large, circumferential pericardial effusion concerning for cardiac tamponade. He was emergently taken to the catheterization lab for pericardiocentesis with drainage of 500cc of serosanguinous fluid. Post-pericardiocentesis ECG revealed resolution of his atrial fibrillation, and unexpectedly, his wide QRS and pre-excitation pattern was replaced by narrow complex sinus rhythm. <h3>Summary</h3> This case illustrates the atypical presentation of cardiac tamponade in patients who have undergone orthotopic heart transplantation. The pre-excitation and wide QRS pattern may be secondary to pericardial irritation from the effusion leading to changes in the conduction properties of a previously concealed accessory cardiac pathway.

Ventricular Preexcitation: An Anomalous Wave Interfering with the Ordered Ventricular Activation.

Ventricular preexcitation is a depolarization of the ventricles that occurs before the conventional sequence, and the electrocardiogram is the specific test for diagnosis. A Kent bundle is the paradigm of ventricular preexcitation, and it is associated with short PR, wide QRS and delta wave. This finding is not always very evident, as it can have different degrees of pre-eccitazione; therefore great diagnostic care must be taken in this field. If not properly identified, the pattern of ventricular preexcitation may lead to an incorrect diagnosis. The methodology of precision electrocardiology is able to confront all these aspects.

Wolff Parkinson white pattern in Danon disease: When preexcitation is not what it seems

Danondisease is a rare genetic disorder with an X-linked dominant inheritance affecting both skeletal and cardiac muscle. Its characteristic cardiac phenotype consists on a severe, non-obstructive and concentric hypertrophic cardiomyopathy (HCM) usually associated with a Wolff-Parkinson-White (WPW) type preexcitation pattern. Whether this corresponds to the presence of an AV or another type of accessory pathways, such as fasciculoventricular pathways (FVP) remains controversial in the literature. However, we describe the case of a teenager with Danon disease and preexcitation who develops a first degree AV block without any change in his QRS morphology, fact that favors the hypothesis of the presence of a FVP. This finding has important clinical implications in the management and prognosis of these complex patients. The absence of an AV accessory pathway decreases their risk of potential SCD in the context of a fast atrial arrhythmia and their chances of having a reentrant AV tachycardia.

P1443Accuracy of three algorithms in predicting accessory pathway localization in a pediatric population with ventricular pre-excitation

Abstract BACKGROUND Prediction of accessory pathway location is extremely important before scheduling ablation, even more in paediatric patients. Given the absence in the literature of conclusive and recent studies that established the best algorithm to predict location in these patients, especially after the introduction of 3D mapping systems, we designed a study to compare three previously published algorithms. AIM The aim of this study is to assess and compare the accuracy in predicting accessory pathway location of the algorithm by Arruda, Boersma and Chiang. METHODS This is a multicenter, observational, retrospective clinical study based on the analysis of the resting 12-leads ECGs of children (aged 0-18 years) with ventricular pre-excitation pattern. The study lasts from January 2013 to June 2019. We analyzed the accuracy (defined as percentage of true positive values) of predicted location by each algorithm, which could include one or more than one of 13 regions around mitral and tricuspid annuli. RESULTS Study population was composed by 120 patients, mean age was 12.7 +/- 3.6 years (height 155.6 +/-19.3 cm and weight 48.3 +/- 17.1 kg). The algorithm by Boersma has the highest percentage of predicted pathway locations that are found to be concordant with the site of successful AP ablation (see table). When we corrected for pre-test probability, the algorithm by Arruda makes the possibility of one specific location 8 times higher, the one by Boersma 6.4 times higher and the one by Chiang 6.9 times higher than by chance. CONCLUSIONS The algorithm by Boersma showed the highest accuracy in accessory pathway location, on the other hand the one by Arruda seems to have the highest corrected accuracy in accessory pathway among children. table 1 Arruda Boersma Chiang Number of locations 13 9 13 Total accuracy 0,617 0,717 0,533 Corrected accuracy per locations 8,0158 6,4494 6,929 Abstract Figure. picture 1

P1262 If anything can go wrong, it will: management of a pericardial effusion in a young patient

Abstract Case Report A 25 year-old male patient with an unremarkable past medical history presented to the Emergency Department due to a hemodynamically stable wide complex tachycardia at 260bpm with no response to adenosine, which was successfully treated with synchronized electrical cardioversion. Post cardioversion EKG revealed a pre excitation pattern and the transthoracic echocardiogram showed a large pericardial effusion with diastolic right atrial collapse. The patient was admitted in the Cardiology Department for emergent pericardiocentesis and further investigation. A total of 800 mL of bloody pericardial fluid was removed, compatible with an exudate, but fluid culture and cytology were inconclusive. Due to a rapid reaccumulation of pericardial fluid, the patient underwent a pericardial window, after which he developed an intractable pleuritic thoracalgia, refractory to the combination of ibuprofen, colchicine and oral steroid, despite the resolution of the pericardial effusion. He was also submitted to an electrophysiologic study with successful ablation of a right sided accessory pathway. Analysis of the pericardial fluid and biopsy were inconclusive once again, including a low level of adenosine deaminase and negative acid-fast bacilli test and nucleic acid amplification test for Mycobacterium tuberculosis. The patient was afebrile and denied any constitutional symptoms or relevant epidemiological context. The remainder etiological study was unremarkable, with the exception of fluctuating antibody titers for adenovirus, Borrelia burgdorferi and Mycoplasma pneumoniae, which were interpreted as a result of cross-reactivity. Nevertheless, a course of 21 days of doxycycline was tried without any significant improvement. Thoracic-abdominal-pelvic CT and PET scan were normal. Direct inoculation in guinea pig led to positive results for Mycobacterium tuberculosis and antituberculous therapy was started. Despite pathogen directed antibiotic treatment, there was no clinical improvement and the pericardial effusion gradually relapsed, evolving to cardiac tamponade requiring emergent drainage. Histologic examination of pericardial fragments finally revealed massive infiltration by an undifferentiated malignant tumor compatible with a malignant epithelioid hemangioendothelioma. Due to the patient’s poor performance status and rapidly deteriorating clinical course, it was decided not to start chemotherapy. The patient eventually died, 6 months after his admission to the ED and 2 weeks after the neoplasm’s diagnosis. Conclusion In regions with a high Tuberculosis incidence, there should be a high degree of suspicion for tuberculous pericarditis, especially in cases of recurrent pericardial effusion. Immunosuppressed individuals, such as oncologic patients, are at an increased risk for tuberculosis. The management of relapsing pericardial effusion remains a diagnostic challenge as described in this clinical case.

Danon disease: Two patients with atrial fibrillation in a single family and review of the literature.

The present study reports on a family with two members affected by Danon disease but having different phenotypes. The clinical manifestations of Danon disease include cardiomyopathy, skeletal myopathy and different degrees of intellectual disability that varies greatly among patients. The present case study reports on two siblings, an older sister and a younger brother, with Danon disease from an affected pedigree, presenting with distinctly different phenotypes. The sister was diagnosed with dilated cardiomyopathy at the age of 26 years with an unfavorable outcome, while her younger brother presented with hypertrophic cardiomyopathy in a relatively stable state. The two probands shared the same mutation, c.974delTinsAA in exon 8, in the lysosomal-associated membrane protein-2 gene. Of note, the two patients had a pre-excitation pattern in the electrocardiogram on initial presentation and later developed atrial fibrillation (AF), which markedly aggravated heart failure. To the best of our knowledge, AF has not been widely reported in patients with Danon disease. The development of AF may have a prognostic value under these circumstances.

Arrhythmias and fasciculoventricular pathways in patients with Danon disease: A single center experience.

Danon disease is a rare X-linked storage disorder characterized by hypertrophic cardiomyopathy leading to arrhythmias and heart failure. A preexcitation pattern on electrocardiogram (ECG) has been described in these patients, however, invasive studies to distinguish between Wolff-Parkinson-White syndrome syndrome and fasciculoventricular pathways (FVP) are limited. The purpose of this study was to delineate the electrophysiological cardiac abnormalities in patients with Danon disease and to describe the presence of FVP in this population. We performed a retrospective study of all patients with a confirmed diagnosis of Danon disease presenting to a single center from May 2005 to May 2018. Baseline demographics, clinical characteristics, ECG findings, and electrophysiology study (EPS) results were collected. Ten patients with Danon disease (30% male, average age 17.4 years) were identified. Seven patients (70%) had tachyarrhythmias including five with atrial arrhythmias and six with nonsustained ventricular tachycardia. Preexcitation pattern on ECG was found in four (40%) patients. Of these, two underwent an EPS which confirmed the presence of an FVP. One patient underwent an adenosine challenge which supported a FVP. Implantable cardioverter defibrillator was placed in five patients for primary prevention with no patients receiving an appropriate discharge. Over a follow-up of 5.3 years, five underwent heart transplantation. This study reports a high incidence of FVP in patients with Danon disease and preexcitation. It underscores an alternate etiology of preexcitation in this population which can potentially be diagnosed without invasive EPS testing. Future multicenter studies are needed to expand this experience.

Differentiation of fasciculoventricular fibers from anteroseptal accessory pathways using the surface electrocardiogram

Fasciculoventricular fibers (FVFs) are responsible for 1%-5% of cases of asymptomatic preexcitation on the surface electrocardiogram (ECG). Unlike ventricular preexcitation seen in Wolff-Parkinson-White (WPW) syndrome, FVFs are not associated with sudden cardiac death from preexcited atrial fibrillation. The purpose of this study was to identify surface ECG variables that differentiate FVFs from true WPW syndrome. This is a retrospective case-control study comparing surface ECG characteristics of patients diagnosed with FVFs (cases) with those of patients with WPW syndrome and anteroseptal accessory pathways (controls) via intracardiac electrophysiology testing at a single institution from 2005 to2017. Twenty-four cases of FVFs confirmed by intracardiac electrophysiology testing were identified and compared with 48 consecutive controls with WPW syndrome and anteroseptal accessory pathways. Patients with WPW syndrome were found to have significantly higher delta wave amplitudes (4.8 ± 2.0 mm vs 1.9 ± 1.3 mm; P < .001), shorter PR intervals (94.6 ± 12.5 ms vs 106.8 ± 13.2 ms; P < .001), and longer QRS intervals (133.6 ± 19.0 ms vs 118.7 ± 24.7 ms; P = .006) than did those with FVFs. Multivariable logistic regression analysis identified the delta wave amplitude as the only independent predictor of WPW syndrome (odds ratio 3.1 per 1-mm increase; bootstrapped 95% confidence interval 1.5-6.4; c statistic 0.90; P = .002). The etiology of preexcitation in patients with an anteroseptal preexcitation pattern, whether because of a benign FVF or because of potentially serious WPW syndrome, can be noninvasively deduced using the surface ECG. A higher delta wave amplitude is an independent risk factor for the presence of WPW syndrome and can accurately distinguish WPW syndrome from a FVF with good test accuracy characteristics.

Mitochondrial DNA mutation "m.3243A>G"-Heterogeneous clinical picture for cardiologists ("m.3243A>G": A phenotypic chameleon).

In general, a mitochondrial disorder is diagnosed on the basis of symptom combinations and confirmed by genetic findings. However, patients carrying the m.3243A>G mutation in the mitochondrial tRNA leucine 1 (MT-TL1) do not always meet all the proposed criteria for the most frequently encountered mitochondrial syndrome "MELAS," an acronym for Mitochondrial Encephalomyopathy, Lactic Acidosis, and at least one Stroke-like episode. We here present various phenotypic characteristics of the mitochondrial mutation m.3243A>G with particular focus on cardiac manifestations. We followed nine patients (1month to 68years old; median 42years; four female and five male) from nine different families with this m.3243A>G mutation in the MT-TL1. The classical "MELAS" criteria are met by only three of these patients. Electrocardiography (ECG) shows preexcitation pattern with short PR intervals and delta waves (Wolff-Parkinson-White) in three patients and sick sinus syndrome plus atrioventricular block I in one patient. Hypertrophic cardiomyopathy was found in eight patients with moderate to severe regurgitation of various valves. Cardiac manifestation can encompass hypertrophic or dilated cardiomyopathy, as well as preexcitation syndromes or conduction delay. In general, the clinical presentation to meet the "MELAS" criteria varies due to heteroplasmy. Thus, cardiologists should screen patients with unexplained cardiac features in the context of deafness, short stature and learning disabilities for mtDNA mutations, especially the m.3243A>G mutation. A clear diagnosis is essential as a basis for prognostic advice concerning the disease course and clinical impact on family testing.

Atypical bypass tracts: can they be recognized during sinus rhythm?

Atypical bypass tracts or variants of ventricular pre-excitation are rare anatomic structures often with rate-dependent slowing in conduction, called decremental conduction. During sinus rhythm, electrocardiographic recognition of those structures may be difficult because unlike in the Wolff-Parkinson-White syndrome where usually overt ventricular pre-excitation is present, the electrocardiogram (ECG) often shows a subtle pre-excitation pattern because of less contribution to ventricular activation over the slow and decrementally conducting bypass. Following the structure described by Ivan Mahaim and Benatt corresponding to a fasciculoventricular pathway, several other new variants of ventricular pre-excitation were reported. In this review, we aim to discuss the electrocardiographic pattern of the different subtypes of variants of ventricular pre-excitation, including the atriofascicular pathway, long and short decrementally conducting atrioventricular pathways, fasciculoventricular pathway, the atrio-Hisian bypass tract, and nodoventricular and nodofascicular fibres. Emphasis will be on the ECG findings during sinus rhythm.