Torsades de Pointes electrical storm in children with KCNH2 mutations.

Congenital long QT syndrome (LQTS) is a genetic heart disorder, which may lead to life-threatening arrhythmias, especially in children. Here, we reported two children who were initially misdiagnosed with epilepsy and experienced Torsades de Pointes (TdP) cardiac electrical storm (ES). Through whole exome sequencing (WES), we identified two Potassium voltage-gated channel subfamily H member 2 (KCHN2) mutations (c.1841 C > T and c.1838 C > T) respectively in a 6-year-old boy and a 13-year-old girl. Clinical data indicated that the QT interval was significantly prolonged, the T-wave pattern of chest V5-V6 leads and limb leads were inverted. Our study suggests that patients with epilepsy, especially those refractory epilepsy with atypical features, need comprehensive evaluation of cardiovascular function. KCNH2 mutation in pore region, QT interval prolongation and T wave inversion are high risk factors for ES. For LQT2 patients with ES, Nadolol and left cardiac sympathetic denervation are indicated, sometimes with an ICD.

Non-specific myocardial fibrosis in young competitive athletes: clinical significance and risk prediction by a powerful machine learning-based model.

BACKGROUND: Non-specific myocardial fibrosis (NSMF) is a heterogeneous entity. We aimed to evaluate young athletes with and without NSMF to establish potentially clinically significance. METHODS: We analysed data from 328 young athletes. We identified 61 with NSMF and compared them with 75 matched controls. Athletes with NSMF were divided into Group 1 (n = 28) with 'minor' fibrosis and Group 2 (n = 33) with non-insertion point fibrosis, defined as 'major'. Athletes were followed-up for adverse events. Finally, we tested various machine learning (ML) algorithms to create a prediction model for 'major' fibrosis. We created 4 different classifiers. RESULTS: Athletes of black ethnicity were more likely to have a subepicardial pattern (OR: 5.0, p = 0.004). Athletes with 'major' fibrosis demonstrated a higher prevalence of lateral T-wave inversion (TWI) ( < 0.001) and ventricular arrhythmias (VEs > 500/24 h, p = 0.046; non-sustained VT, p = 0.043). Athletes with 'minor' fibrosis demonstrated higher right ventricular volumes (p = 0.013), maximum Watts (p = 0.022) and maximum VO2 (p = 0.005). Lateral TWI (p = 0.026) and VO2 < 44 mL/min/Kg (p = 0.040) remained the only significant predictors for 'major' fibrosis. During follow up, athletes with 'major' fibrosis were 9.1 times more likely to exhibit adverse events (OR 13.4, p = 0.041). All ML models outperformed the benchmark method in predicting significant MF, best accuracy achieved by the random forest classifier (90%). CONCLUSIONS: Lateral TWI and reduced exercise performance are associated with higher burden of fibrosis. Fibrosis was associated with increased ventricular arrhythmia and adverse events. A comprehensive assessment can help develop a ML-based model for significant fibrosis, which could also guide clinical practice and appropriate CMR referrals.

T Wave Inversion: A Screening Tool for Rapidly Differentiating Acute Coronary Syndrome and Pulmonary Embolism.

Introduction Acute coronary syndrome (ACS) and acute pulmonary embolism (PE) are life-threatening conditions with similar clinical presentations. As current diagnostic tools, such as computed tomography pulmonary angiography, for distinguishing between these two conditions are time-consuming and may not be available in all settings, we tried in this study to devise a diagnostic tool based on electrocardiography to distinguish between ACS and acute PE based on T wave features. Methods Medical records of patients with diagnoses of ACS and acute PE, who were referred to three hospitals affiliated with Shiraz University of Medical Sciences, Shiraz, Iran, from March 2019 to March 2021, were evaluated. One expert cardiologist read patients' electrocardiograms (ECGs). All ECGs were recorded at the standard 25 mm/s and 10 mm/mV. The sum of T wave inversion or TWI (mV) in consecutive leads, including anterior leads (V1, V2, V3, and V4), inferior leads (II, III, aVF), and lateral leads (I, aVL, V5, and V6) were calculated to estimate the cut-off points used to differentiate ACS versus acute PE. The receiver operating characteristic (ROC) curve was used to estimate the diagnostic accuracy of T wave changes. The Youden index was used to calculate the optimum cut-offs for sensitivity and specificity. Results Of 151 patients with a mean age of 55.44±12.88 years, 74 were in the acute PE and 77 were in the ACS groups. The results showed that the TWI sum in anterior leads >1.2 mV (P<0.001), in lateral leads >0.9 mV (P<0.001), in anterior-to-inferior leads ratio >12 (P<0.001), and V4/V1 leads ratio >4 (P<0.001) rules out acute PE. Anterior-to-lateral TWI ratio (AUC=0.807, sensitivity=70.3%, specificity=10%) was significantly distinctive among ACS and acute PE patients. Conclusion TWI sum in anterior leads >1.2 mV, in lateral leads >0.9 mV, in anterior-to-inferior leads ratio >12, and in V4/V1 leads ratio >4 rules out acute PE. The anterior-to-lateral TWI ratio obtained from patients' ECG was significantly distinctive among the patients and can be used as a screening tool.

A right ventricular bulge: A clinical dilemma in diagnosis.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease characterized by progressive fibrofatty tissue replacement of the myocardium. Asymptomatic individuals can often present for the first time with acute cardiac symptoms, such as syncope and ventricular arrhythmias or sudden cardiac death (SCD), which can occur in young and athletic populations. In the field of inherited cardiomyopathies, ARVC is one of the most challenging to diagnose due to its variable expressivity, incomplete penetrance, and lack of specific, unique diagnostic criteria. Without additional clinical findings or context, current imaging modalities are unable to definitively distinguish ARVC from other disease entities. Right ventricular (RV) structural changes can lead to prominent ARVC features. An important component of the 2010 revised task force criteria (TFC) is the assessment of RV wall motion contraction by echocardiography; however, this can be difficult to assess. This case report explores the diagnostic criteria used for ARVC and the role of RV wall motion contraction in the diagnosis.

Stroke on ECG: a cerebral T-wave change secondary to acute carbon monoxide poisoning.

In clinical management of carbon monoxide (CO) poisoning, serum cardiac enzyme biomarkers and electrocardiogram (ECG) are both highly recommended emergency check-ups to evaluate myocardial injuries. Medical imaging - including head CT or MRI - are not routine for CO poisoning emergency management. We herein report on a comatose patient who was diagnosed with cerebral infarction secondary to 24 hours previous acute CO poisoning, warned by a typical cerebral-type T waves on ECG in advance, and confirmed by a head MRI. Fortunately, the patient made a full recovery based on a timely treatment with medications and hyperbaric oxygen (HBO2) therapy. We would like to propose that a vital, stable, conscious CO poisoning patient who remains a higher risk for hemorrhagic or ischemic stroke should be closely monitored for potential neurological abnormalities, and a continuous ECG monitoring should be reinforced throughout the treatment. A head MRI or CT is a priority in evaluating the secondary cerebral stroke and should be arranged immediately in the event of an abnormal ECG or if unusual new symptoms are apparent.

The role of Italian pre-participation screening in early detection of cardiomyopathies: what is the meaning of T wave inversion in young athletes?

INTRODUCTION: The presence of T wave inversion on screening electrocardiogram may represent an early sign of cardiomyopathies in athletes. This finding even in very young athletes can generate some suspicion and may determine a contraindication to practice competitive sport. The aim of this study is to evaluate the prevalence of T wave inversion in a population of young competitive athletes and determine whether they can be associated with the occurrence of cardiomyopathies in the absence of other pathological features. METHODS: A prospective cross-sectional study was carried out and 581 subjects were screened for competitive sport eligibility. Based on inclusion/exclusion criteria, 53 athletes showed T wave inversion and they were selected to undergo further investigations. RESULTS: In 32,1% of cases, we have identified the cause of T wave inversions and we suspended them from competition. In particular, in 15% of athletes who showed T wave inversions, we found cardiomyopathies. DISCUSSION: Prevalence of T wave inversion in this population of athletes was 9,1%. At the end of second and third-level evaluations, eight athletes with T wave inversion showed an early form of cardiomyopathy and were suspended from competitive sport. Most of them showed T wave inversion in infero-lateral leads on electrocardiogram. CONCLUSION: The probability that competitive athletes have a concealed cardiomyopathy is low, but not negligible. Pre-participation screening for competitive sport activity represents an excellent opportunity to early identify cardiomyopathies and other pathologies that increase the risk of sudden death in apparently healthy young athletes.

Recurrent ventricular arrhythmias and heart failure induced by osimertinib- a case report.

Background: Osimertinib is a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor that has become the first-line treatment for non-small cell lung cancer harboring EGFR mutations, with the potential risk of QT prolongation and heart failure. However, few cases have reported malignant ventricular arrhythmias. Here, we report a case of recurrent ventricular fibrillation (VF) and Torsade de Pointes (TdP) secondary to QT prolongation and heart failure induced by osimertinib. Case summary: A 70-year-old woman presented with chest tightness and dyspnea for 1 week and ventricular fibrillation upon admission, with a medical history of lung adenocarcinoma harboring an EGFR exon 21 p.L858R mutation. She was under osimertinib for 3 months. Electrocardiography after defibrillation suggested QTc prolongation (655 ms) and T wave alternans. Ultrasound cardiography displayed left ventricular ejection fraction (LVEF) of 29% and severe mitral regurgitation. Laboratory tests indicated elevated N-terminal pro-B-type natriuretic peptide and hypokalemia. Genetic testing suggested no pathogenic mutations. We considered acquired long QT syndrome and heart failure with reduced ejection fraction induced by osimertinib as the chief causes of ventricular arrhythmia and hypokalemia as an important trigger. Despite intubation, sedation, and the administration intravenous magnesium and potassium and lidocaine, the patient presented with recurrent TdP, which was managed by a low dose of isoproterenol (ISO, 0.17 ug/min). An implantable cardioverter defibrillator was declined. The patient is surviving without any relapse, with QTc of 490 ms and LVEF of 42% after a 6-month follow up. Conclusion: Regular monitoring is required during osimertinib administration, considering the risk of life-threatening cardiac events, such as malignant arrhythmias and heart failure. ISO, with an individual dose and target heart rate, may be beneficial for terminating TdP during poor response to other therapies.

The Epileptic Heart Syndrome: Epidemiology, pathophysiology and clinical detection.

Population studies report elevated incidence of cardiovascular events in patients with chronic epilepsy. Multiple pathophysiologic processes have been implicated, including accelerated atherosclerosis, myocardial infarction, altered autonomic tone, heart failure, atrial and ventricular arrhythmias, and hyperlipidemia. These deleterious influences on the cardiovascular system have been attributed to seizure-induced surges in catecholamines and hypoxemic damage to the heart and coronary vasculature. Certain antiseizure medications can accelerate heart disease through enzyme-inducing increases in plasma lipids and/or increasing risk for life-threatening ventricular arrhythmias as a result of sodium channel blockade. In this review, we propose that this suite of pathophysiologic processes constitutes "The Epileptic Heart Syndrome." We further propose that this condition can be diagnosed using standard electrocardiography, echocardiography, and lipid panels. The ultimate goal of this syndromic approach is to evaluate cardiac risk in patients with chronic epilepsy and to promote improved diagnostic strategies to reduce premature cardiac death.

Implantable loop recorder uncovered torsades de pointes in long-QT syndrome type 1 with multi cause of syncope.

An implantable loop recorder (ILR) is now widely used for differential diagnosis of unexplained syncope or recurrent syncope with unknown causes. In the inherited arrhythmia syndromes, ILR may be useful for management of the therapeutic strategies; however, there is no obvious evidence to uncover arrhythmic syncope by ILR in long-QT syndrome (LQTS) patients. Here we experienced a 19-year-old female patient with LQTS type 1 who had recurrent syncope even after beta-blocker therapy but no arrhythmias were documented, and some episodes might be due to non-cardiogenic causes. Implantable cardioverter defibrillator (ICD) therapy was also recommended; however, she could not accept ICD but was implanted with ILR for further continuous monitoring. Two years later, she suffered syncope during a brief run, and ILR recorded an electrocardiogram at that moment. Thus a marked QT interval prolongation as well as T-wave alternance resulting in development of torsades de pointes could be detected. Although ILR is just a diagnostic tool but does not prevent sudden cardiac death, most arrhythmic events in LQTS are transient and sometimes hard to be diagnosed as arrhythmic syncope. ILR may provide direct supportive evidence to select the optimal therapeutic strategy in cases where syncope is difficult to diagnose. Learning objective: Long-QT syndrome (LQTS) patients often suffer recurrent syncope even after beta-blocker therapy, but torsades de pointes (TdP) is not always detected by standard 12­lead electrocardiogram or Holter monitoring, and some syncope might be non-cardiogenic. In this case, implantable loop recorder (ILR) documented the evidence of QT interval prolongation and beat-by-beat T-wave alternance subsequent TdP. Thus, ILR may provide useful evidence for the optimal treatment strategy in LQTS cases where syncope is difficult to diagnose.

Apicolateral bulge: A potential mimic of arrhythmogenic right ventricular cardiomyopathy in a professional athlete-A case report and literature review.

Soccer is the most popular sport in the world, with over 265 million active players and approximately 0.05% professional players worldwide. The Fédération Internationale de Football Association (FIFA) has made preparticipation screening recommendations which involve electrocardiography and echocardiography being performed prior to international competition. The aim of preparticipation cardiovascular screening in young athletes is to detect asymptomatic individuals with cardiovascular disease at risk of sudden cardiac death (SCD). The incidence of SCD in young athletes (age≤ 35 years) is 0.6-3.6 in 100,000 persons/year, with most deaths due to cardiovascular causes. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is one of the leading causes of SCD in young athletes. It is a genetic disease characterized by progressive fibrofatty replacement of the myocardium with variable phenotypic expression. Exercise-induced cardiac remodeling in conjunction with extensive T-wave inversion raises concern for ARVC. This case report and literature review explores a potential mimic for ARVC, the role of cardiovascular screening in sport, and the use of a multimodality approach for risk stratification and management.

A young woman presenting with dyspnoea and diffuse T-wave inversions: a case report.

Background: T-wave inversions on electrocardiograms (ECGs) indicate a variety of conditions, such as coronary artery disease, myocarditis, and cardiomyopathy. Pulmonary artery stenosis (PAS) and pulmonary hypertension (PH) may cause right ventricular enlargement and ischaemia, which are reflected as T-wave inversions on ECGs. Continuous ECG monitoring is crucial for detecting dynamic changes indicative of PAS progression and reversal in right heart remodelling. Case summary: This report presents the case of a young woman who experienced exertional dyspnoea for 5 years with ECG findings showing T-wave inversions across multiple leads. The patient was diagnosed with PAS and PH caused by Takayasu arteritis (TA). Following three successful balloon pulmonary angioplasty sessions, the patient exhibited significant clinical improvement, including the remission of PAS and PH. Throughout a 59-month cumulative follow-up period, the sustained effectiveness of the treatment was evidenced by the regression of right heart remodelling, as manifested in the normalization of the initially inverted T-waves on the ECG. Discussion: Electrocardiogram changes, including right axis deviation, right bundle branch block, a deep S wave in lead I (R/S < 1), and a prominent R wave in lead aVR (R/Q > 1), have been termed PAS syndrome, often linked to TA-associated PAS, especially in young East Asian females. Early diagnosis is crucial but challenging due to atypical symptoms. The non-invasive ECG is vital for detection, with balloon pulmonary angioplasty serving as an effective treatment for TA-induced PAS when surgery is not an option, improving outcomes and potentially reversing right heart remodelling.

T-Wave Alternans Measured by 24-Hour Ambulatory Recordings Rather Than Exercise Stress Tests as a Risk Stratification Marker in Patients With Long QT Syndrome.

BACKGROUND: Few small-sample studies have quantified the T-wave alternans (TWA) value by 24-hour ambulatory recordings or exercise stress tests in patients with long QT syndrome (LQTS). The cutoff point of TWA ≥47 µV was based on patients with myocardial infarction. In our study, we aimed to (1) evaluate the association of TWA with life-threatening arrhythmic events (LAEs); (2) compare the predictive model of LAEs according to the TWA value measured by 24-hour ambulatory recordings and exercise stress tests; and (3) propose a cutoff point for the high risk of LAEs in patients with LQTS. METHODS AND RESULTS: The study cohort included 110 patients with LQTS referred to our hospital, and the primary outcome was LAEs. Thirty-one patients with LQTS (31/110 [28.2%]) developed LAEs during the following 24 (12-47) months. Peak TWA value quantified from 12 leads by 24-hour ambulatory recordings in patients with LQTS with LAEs (LQTS-LAEs group) was significantly higher than LQTS without LAEs (LQTS-non-LAEs group) (64.0 [42.0-86.0] µV versus 43.0 [36.0-53.0] µV; P<0.01). There was no statistical difference in TWA value measured by exercise stress tests between the 2 groups (69.0 [54.5-127.5] µV versus 68.5 [53.3-99.8] µV; P=0.871). The new cutoff point of the peak TWA value measured by 24-hour ambulatory recordings was 55.5 µV, with a sensitivity of 75.0% and a specificity of 78.6%. A univariate Cox regression analysis revealed that TWA value ≥55.5 µV was a strong predictor of LAEs (hazard ratio [HR], 4.5 [2.1-9.6]; P<0.001]. A multivariate Cox regression analysis indicated that TWA value ≥55.5 µV remained significant (HR, 2.7 [1.1-6.8]; P=0.034). CONCLUSIONS: Peak TWA measured by 24-hour ambulatory recordings was a more favorable risk stratification marker than exercise stress tests for patients with LQTS.

Cardiac repolarisation indices are associated with oxygen consumption during maximal exercise test in highly-trained cross-country skiers.

The objective of this study was to test the vectorelectrocardiographic T-wave characteristics for their associations with oxygen consumption (VO2) and physical performance during a maximal cardiopulmonary exercise test (CPET) in highly trained cross-country skiers. Male highly trained cross-country skiers (n = 30) performed the maximal CPET on the bicycle ergospirometric "Oxycon Pro" system with simultaneous oxygen consumption (VO2) and electrocardiogram recording. The measurements were done at rest; the stage preceding anaerobic threshold (preAnT); peak load; and recovery. The anaerobic threshold was estimated by respiratory exchange ratio. Physical performance was estimated by maximal oxygen consumption (VO2max/kg). VECG characteristics were calculated using Kors transformation procedure. During the test, the magnitudes of T-vector, Tx and Ty components decreased until preAnT, then stayed relatively stable until peak load, and reversed during recovery. In univariate linear regression analysis, T-vector amplitude and Tx, Ty and Tz magnitudes were associated with VO2/kg during the test (p < 0.010). The baseline T-vector characteristics were not associated with physical performance. At the preAnT stage, Tx and T-vector amplitude were associated with VO2max/kg (RC 12.70, 95% CI 0.68-24.73, p = 0.039 and RC 10.64, 95% CI 1.62-19.67, p = 0.023, respectively).

Repositioning of the Insertable Cardiac Monitor Through the Same Incision to Avoid T-wave Oversensing.

Insertable cardiac monitor (ICM), used for long-term heart rhythm monitoring, often experiences diagnostic challenges such as T-wave oversensing, leading to false positives. This case report presents a novel approach to rectifying T-wave oversensing in ICM implantations. In this case, we are sharing a 38-year-old female with recurrent syncopal episodes who underwent ICM implantation (LUX-Dx™, ICM-Boston Scientific, Marlborough, United States). Post-implantation, T-wave oversensing was detected. Instead of the usual readjustment or reinsertion, we employed a non-invasive method of repositioning the ICM at a 45-degree angle toward the right side of the heart through the existing incision. This effectively resolved the oversensing issue without complications or the need for a new incision. ICMs are vital in linking symptoms to arrhythmias, especially in cases where standard diagnostic tools fall short. Despite their utility, ICMs are susceptible to T-wave oversensing due to subcutaneous placement. Our case demonstrates a successful alternative approach to address this, enhancing ICM's diagnostic accuracy without invasive procedures. This case highlights the potential of repositioning ICMs as a simple, non-invasive solution to overcome T-wave oversensing issues. It calls for further research and discussion within the medical community to explore its wider applicability, thereby improving ICM efficacy in clinical practice. The patient experienced no complications following the procedure during the three-month visit with appropriate sensing, validating this approach as a feasible option in similar cases.

Methodological identification of anomalies episodes in ECG streams: a systematic mapping study.

An electrocardiogram is a medical examination tool for measuring different patterns of heart blood flow circle either in the form of usual or non-invasive patterns. These patterns are useful for the identification of morbidity condition of the heart especially in certain conditions of heart abnormality and arrhythmia. Myocardial infarction (MI) is one of them that happened due to sudden blockage of blood by the cause of malfunction of heart. In electrocardiography (ECG) intensity of MI is highlighted on the basis of unusual patterns of T wave changes. Various studies have contributed for MI through T wave's classification, but more to the point of T wave has always attracted the ECG researchers. Methodology. This Study is primarily designed for proposing the combination of latest methods that are worked for the solutions of pre-defined research questions. Such solutions are designed in the form of the systematic review process (SLR) by following the Kitchen ham guidance. The literature survey is a two phase's process, at first phase collect the articles that were published in IEEE Xplore, Scopus, science direct and Springer from 2008 to 2023. It consist of steps; the first level is executed by filtrating the articles on the basis of keyword phase of title and abstract filter. Similarly, at two level the manuscripts are scanned through filter of eligibility criteria of articles selection. The last level belongs to the quality assessment of articles, in such level articles are rectified through evaluation of domain experts. Results. Finally, the selected articles are addressed with research questions and briefly discuss these selected state-of-the-art methods that are worked for the T wave classification. These address units behave as solutions to research problems that are highlighted in the form of research questions. Conclusion and future directions. During the survey process for these solutions, we got some critical observations in the form of gaps that reflected the other directions for researchers. In which feature engineering, different dependencies of ECG features and dimensional reduction of ECG for the better ECG analysis are reflection of future directions.

Empagliflozin's role in reducing ventricular repolarization heterogeneity: insights into cardiovascular mortality decline from the EMPATHY-HEART trial.

BACKGROUND: The incidence of myocardial infarction (MI) and sudden cardiac death (SCD) is significantly higher in individuals with Type 2 Diabetes Mellitus (T2DM) than in the general population. Strategies for the prevention of fatal arrhythmias are often insufficient, highlighting the need for additional non-invasive diagnostic tools. The T-wave heterogeneity (TWH) index measures variations in ventricular repolarization and has emerged as a promising predictor for severe ventricular arrhythmias. Although the EMPA-REG trial reported reduced cardiovascular mortality with empagliflozin, the underlying mechanisms remain unclear. This study investigates the potential of empagliflozin in mitigating cardiac electrical instability in patients with T2DM and coronary heart disease (CHD) by examining changes in TWH. METHODS: Participants were adult outpatients with T2DM and CHD who exhibited TWH > 80 µV at baseline. They received a 25 mg daily dose of empagliflozin and were evaluated clinically including electrocardiogram (ECG) measurements at baseline and after 4 weeks. TWH was computed from leads V4, V5, and V6 using a validated technique. The primary study outcome was a significant (p < 0.05) change in TWH following empagliflozin administration. RESULTS: An initial review of 6,000 medical records pinpointed 800 patients for TWH evaluation. Of these, 412 exhibited TWH above 80 µV, with 97 completing clinical assessments and 90 meeting the criteria for high cardiovascular risk enrollment. Empagliflozin adherence exceeded 80%, resulting in notable reductions in blood pressure without affecting heart rate. Side effects were generally mild, with 13.3% experiencing Level 1 hypoglycemia, alongside infrequent urinary and genital infections. The treatment consistently reduced mean TWH from 116 to 103 µV (p = 0.01). CONCLUSIONS: The EMPATHY-HEART trial preliminarily suggests that empagliflozin decreases heterogeneity in ventricular repolarization among patients with T2DM and CHD. This reduction in TWH may provide insight into the mechanism behind the decreased cardiovascular mortality observed in previous trials, potentially offering a therapeutic pathway to mitigate the risk of severe arrhythmias in this population. TRIAL REGISTRATION: NCT: 04117763.

Evaluation of T-wave memory after accessory pathway ablation in pediatric patients with Wolff-Parkinson-White syndrome.

BACKGROUND: T-wave memory (TWM) is a rare cause of T-wave inversion (TWI). Alterations in ventricular activation due to abnormal depolarization may cause repolarization abnormalities on the ECG, even if myocardial conduction returns to normal. These repolarization changes are defined as TWM. In our study, we aimed to determine the frequency of TWM development and the predictors affecting it in the pediatric population who underwent accessory pathway (AP) ablation due to Wolff-Parkinson-White (WPW) syndrome. METHODS: The data of patients with manifest AP who underwent electrophysiological studies and ablation between 2015 and 2021 were retrospectively analyzed. The study included 180 patients who were under 21 years of age and had at least one year of follow-up after ablation. Patients with structural heart disease, intermittent WPWs, recurrent ablation, other arrhythmia substrates, and those with less than one-year follow-up were excluded from the study. The ECG data of the patients before the procedure, in the first 24 h after the procedure, three months, and in the first year were recorded. The standard ablation technique was used in all patients. RESULTS: Postprocedure TWM was observed in 116 (64.4%) patients. Ninety-three patients (51.7%) had a right-sided AP, and 87 patients (48.3%) had a left-sided AP. The presence of posteroseptal AP was found to be significantly higher in the group that developed TWM. Of these patients, 107 (93.1%) patients showed improvement at the end of the first year. Preprocedural absolute QRS-T angle, postprocedural PR interval, and right posteroseptal pathway location were identified as predictors of TWM. CONCLUSION: The development of TWM is particularly associated with the right-sided pathway location, especially the right posteroseptal pathway location. The predictors of TWM are the preprocedural QRS-T angle, the postprocedural PR interval, and the presence of the right posteroseptal AP.

Giant T waves and QT interval prolongation associated with guanfacine toxicity.

INTRODUCTION: Guanfacine is a central α2-adrenergic receptor agonist that produces drowsiness, bradycardia, hypotension, and occasionally QT interval prolongation. We discuss giant T waves associated with guanfacine toxicity. CASE SUMMARIES: Three patients presented to the hospital with histories and physical findings compatible with guanfacine toxicity. Supratherapeutic concentrations were confirmed in two of them. All three developed QT interval prolongation and giant T waves on the electrocardiogram. Giant T waves occur commonly in patients with acute myocardial infarct and hyperkalemia, as well as rarely with a number of other cardiac and non-cardiac causes. CONCLUSION: Guanfacine toxicity may cause the novel electrocardiographic finding of 'giant T wave with QT interval prolongation'. Further studies are warranted to investigate the association between the novel electrocardiographic finding and guanfacine toxicity, as well as its diagnostic utility in such cases.