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Background: Patients with Barth syndrome (BTHS) can present with cardiomyopathy. BTHS subjects are at risk for cardiac adverse outcomes throughout life, including malignant arrhythmias and death. Electrocardiogram (ECG) parameters have never been assessed as a tool to predict adverse outcomes in individuals with BTHS. Objectives: The purpose of this study was to identify any ECG parameters including QRS fragmentation, presence of arrhythmia, or abnormal intervals that could predict adverse outcomes and cardiac death among the BTHS population. Methods: We performed a retrospective case referent study on subjects with BTHS (n=43), and compared them with our reference group, subjects with idiopathic dilated cardiomyopathy (DCM) from a single institution (n=53) from 2007-2021. BTHS data was obtained from subjects attending the biennial Barth Syndrome Foundation International Scientific, Medical, and Family Conferences (BSFISMFC) from 2002-2018. ECG data from first and last available ECG's prior to an adverse event or cardiac death was analyzed, and then multivariable regression was performed to determine odd ratios between ECG characteristics and adverse events/cardiac death. Results: No ECG variables were statistically significant predictors of adverse events or cardiac death in the BTHS group. Last ECG QRS fragmentation trended to statistically significance (OR 13.3, p=0.12) in predicting adverse events in the DCM group. Conclusion: No ECG parameters, including QRS fragmentation, presence of arrhythmia, or abnormal interval values predict adverse events or cardiac death among BTHS patients. QRS fragmentation may be a predictor of adverse events in the DCM population.

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Background: Barium, as a heavy divalent alkaline earth metal, can be found in various products such as rodenticides, insecticides, depilatories, and fireworks. Barium can be highly toxic upon both acute and chronic exposure. The toxicity of barium compounds is dependent on their solubility. Both suicidal and accidental exposures to soluble barium can cause toxicity. Case summary: We report a case characterized by two different wide QRS complex tachycardia in a patient with acute barium poisoning, one due to barium-induced ventricular tachycardia (VT) under hypokalemia and, subsequently, sino-ventricular conduction with intraventricular conduction delay due to hyperkalemia after aggressive potassium supplementation. The latter may be misdiagnosed as VT for the history of acute barium poisoning and the absence of peaked T wave in hyperkalemia. Of note, another hemodynamically unstable VT and profound hypokalemia occurred during the potassium-lowering therapy, which, in addition to barium poisoning, may also be due to the iatrogenic hypokalemia. We also observed the prominent T-U waves at serum potassium of 4.6 mM 12 hours after admission, which may indicate that barium had not been completely cleared from the plasma at that moment. There are some parallels to the Andersen-Tawil syndrome with prominent T-U waves and risk of ventricular tachycardias. To our knowledge, this is the first case report of conversion from hypokalemia to hyperkalemia, and in a short moment, from hyperkalemia to hypokalemia, in acute barium poisoning. Conclusion: In addition to profound hypokalemia secondary to acute barium poisoning, hyperkalemia may also occur after aggressive potassium supplementation. A more careful rather than too aggressive potassium supplementation may be suitable in these cases of hypokalemia due to an intracellular shift of potassium. And a iatrogenic hypokalemia risk in the treatment of rebound hyperkalemia in barium poisoning must be considered.

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Clinical suspicion, clinical presentation, and electrocardiogram can help clinicians diagnose flecainide toxicity. Currently, there are no guidelines for the management of patients with flecainide toxicity. Sodium bicarbonate, lipid emulsion therapy, and extracorporeal life support have been used in this setting. Amiodarone and lidocaine can be used for the management of wide QRS complex tachycardias in hemodynamically stable patients with flecainide toxicity.

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INTRODUCTION: Tricyclic antidepressants often cause drug-induced QRS complex prolongation in overdose but are now less commonly prescribed. We sought to determine, among a contemporary cohort of patients, the pharmaceuticals independently associated with QRS complex prolongation in acute overdose. METHODS: We performed secondary analysis of data from the Toxicology Investigators Consortium (ToxIC) Core Registry. We included adult patients presenting from January 2016 through March 2023 with acute or acute-on-chronic pharmaceutical exposures. The primary outcome was QRS complex prolongation >0.12 s. Secondary outcomes included cardiac arrest, death, ventricular dysrhythmia, intensive care unit admission, initiation of vasopressors, and treatment with sodium bicarbonate. We used a multivariable logistic regression model with QRS complex prolongation as the outcome and individual pharmaceuticals of interest as independent variables. We assessed yearly trends of the contribution of relevant pharmaceuticals to QRS complex prolongation since 2016. RESULTS: Of 11,945 patients in the total cohort (median age 37 years, 6,652 [55.7%] female), 366 (3.1%) developed QRS complex prolongation. Of 9,417 patients included in the model, 290 (3.1%) developed QRS complex prolongation. Amitriptyline, nortriptyline, doxepin, imipramine, noxiptiline, bupropion, flecainide, carvedilol, propranolol, diphenhydramine, and lamotrigine poisonings were independent predictors of QRS complex prolongation. Flecainide poisoning conferred the greatest odds of QRS complex prolongation (OR 574.1; 95% CI: 88.3-12,747). The contribution of tricyclic antidepressants to QRS complex prolongation decreased from 38.8% to 17.6% of all patients with QRS complex prolongation from 2016 to 2022. In 2022, the proportion of QRS complex prolongation from diphenhydramine (20.6%) surpassed that of tricyclic antidepressants. DISCUSSION: This study provides insights into contemporary pharmaceutical poisoning associated with QRS complex prolongation. Tricyclic antidepressants remain clinically relevant exposures but are no longer the most common cause of drug-induced QRS complex prolongation. CONCLUSIONS: Bupropion, diphenhydramine, and antidysrhythmics are increasingly common causes of QRS complex prolongation, each associated with numerous severe outcomes in poisoning. Greater safety measures to protect patients from cardiovascular toxicity from these pharmaceuticals are warranted.

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BACKGROUND: Although output-dependent QRS transition is a specific indicator that confirms left bundle branch (LBB) capture during left bundle branch area pacing (LBBAP), its durability remains unclear. OBJECTIVE: The purpose of this study was to evaluate the presence of output-dependent QRS transition and capture thresholds of the LBB and left ventricular septal myocardium immediately and up to 1 year after the LBBAP procedure. METHODS: We enrolled 129 patients with successful LBBAP who were available for 1-year follow-up postoperatively. Threshold testing was performed immediately after LBBAP on postoperative day 0 (POD-0) and after 3 days (POD-3), 6 months (POD-180), and 1 year (POD-360). RESULTS: Output-dependent QRS transition persisted in 64 patients (88%) on POD-360, from among the 73 patients with output-dependent QRS transition on POD-0. In contrast, 55 of 56 patients without QRS transition on POD-0 (98%) did not exhibit QRS transition thereafter. LBB thresholds were slightly elevated on POD-360, albeit without statistical significance, compared with those on POD-0 (1.22 ± 1.00 V vs 1.43 ± 1.29 V at 0.4 ms; P = .26). The LBB thresholds increased by ≥1.5 V in 7 patients (11%). However, in 93% of patients with an LBB threshold of ≤2.5 V on POD-0, LBB capture was maintained at 2.5 V on POD-360. Left ventricular septal thresholds were similar on POD-0 and POD-360 (0.81 ± 0.36 V vs 0.83 ± 0.24 V; P = 1.0) and did not increase by ≥1.5 V in any patient. CONCLUSION: Output-dependent QRS transitions were highly reproducible after implantation. Furthermore, LBB thresholds remained stable in most cases during the first postoperative year.

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Objective: To assess the changes in QRS duration (△QRSd) before and after primary percutaneous coronary intervention(PPCI) regarding the relation of left ventricular ejection fraction (LVEF) in patients after a first acute ST segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PPCI). Methods: A total of 244 patients with STEMI were enrolled, and clinical, biochemical, and angiographic parameters were compared between two groups based on LVEF at 6 months post-discharge. QRS duration (QRSd) was analyzed in relation to LVEF, and feature selection using least absolute shrinkage and selection operator(LASSO) regression was performed. Logistic regression analysis and receiver operating characteristic (ROC) curve evaluation were conducted to identify predictors and assess model efficacy. Results: Significant differences were observed between the two groups in terms of various parameters, including age, time from symptom onset to balloon dilation (STB), N-terminal pro B-type natriuretic peptide (NT-proBNP) levels, Left ventricular end-diastolic volume(LVEDV) at baseline, left ventricular end-systolic volume(LVESV)at baseline, left ventricular end-diastolic diameter (LVDD)at baseline and six months, hospital length of stay(days), ST-segment resolution (STR), the left anterior descending artery as the infarction-related artery (IRA-LAD), frequency of TIMI 3 flow post PPCI, thrombus aspiration and/or intracoronary thrombolysis, the use of tirofiban, and the number of implanted stents(stents).In addition, postoperative QRSd and △QRSd were significantly higher in patients with left ventricular systolic dysfunction(LVSD). LASSO regression selected six variables as predictors of postoperative LVEF. Logistic regression analysis identified age, STB, NT-proBNP, LVESV at baseline,△QRSd, and stents, as independent factors associated with LVSD within six months for patients with a first occurrence of STEMI. The models achieved AUC values of 0.906 (using ΔQRSd),0.922(using 6 variables excluding ΔQRSd) and 0.962 (using 6 variables). Conclusion: This study identified ΔQRSd as a potential predictor of LVSD in patients with STEMI. The developed models showed good efficacy in predicting postoperative LVEF changes. These findings may contribute to risk stratification and individualized management strategies for STEMI patients.

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The case of a 72-year-old female patient with arrhythmogenic syncope associated with a combination therapy of flecainide and lacosamide is presented. The authors believe in an additive effect of both drugs on myocardial voltage-gated sodium channels with extraordinary QRS widening, exit block with temporary pacing and complete reversibility through infusion of sodium bicarbonate as bail-out therapy.

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Background: Celiac Disease (CD) is characterized by small intestine involvement. However, cardiac manifestations may also be seen in the clinical course. The significance of the QRS prolongation and the presence of QRS fragmentation (fQRS) has been previously studied in many chronic inflammatory disorders as an independent predictor of cardiac manifestations. The study aimed to evaluate the QRS duration and presence of fQRS in patients with CD. Methods: 164 patients with CD and 162 healthy controls were included in the present study. QRS duration and presence of fQRS were calculated from the 12-lead electrocardiogram and compared between groups. The association between these parameters and disease duration was also evaluated. Results: QRS duration was found to be higher in the CD group compared to the control group (83 (76.8-93) vs. 91 (84-94), p<0.001). The presence of fQRS was demonstrated to be higher in the CD group (n=68 (41.5%) vs n=42 (25.9%), p=0.003). Notably, QRS duration was positively correlated with disease duration (Spearman's Rho= 0.47, p<0.001). In addition, disease duration was significantly higher in the fQRS (+) group (60 (23,5-144) vs. 28,5 (15-71,5), p=0.002). Conclusion: This study revealed that QRS prolongation and the presence of fQRS were higher in patients with CD. The presence of these findings may be an indicator of early subclinical cardiac involvement, especially in those with long disease duration. Thus, patients with these ECG findings can be considered for further cardiac evaluation.

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Background: Wide QRS complex (QRS) tachycardia in patients with atrial fibrillation (AF) or atrial flutter treated with antiarrhythmic drugs can occur for a variety of reasons and needs careful evaluation for appropriate management of the patient. Case summary: We report a case of wide QRS complex tachycardia in a patient with AF treated with Flecainide who received multiple external cardioversion attempts for a presumed diagnosis of ventricular tachycardia. Intravenous Diltiazem and an oral beta-blocker led to the resolution of wide QRS complex tachycardia. Discussion: Wide QRS tachycardia due to pro-arrhythmic effect or rate-dependency phenomenon of antiarrhythmic agents should be included in the differentials. In this brief report, we discuss the differential diagnosis and outline a practical approach for acute and long-term management of these patients.

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Anamorelin, a ghrelin receptor agonist, is used for cancer-related cachexia but can induce life-threatening arrhythmias. A case study illustrates an extremely wide QRS tachycardia, posing diagnostic challenges. Anamorelin cessation led to normalization, highlighting the importance of ECG monitoring, particularly in liver-compromised patients, and hemodynamic support are crucial during suspected toxicity.

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BACKGROUND: QRS morphology can change during ventricular arrhythmias (VAs) with the appearance of bundle branch block (BBB). METHODS: We retrospectively investigated 195 consecutive patients who underwent an initial ablation of VA. The study inclusion criteria were VAs that were successfully ablated in the outflow tract (OT) and in whom right bundle branch block (RBBB) was induced by catheter manipulation close to the His bundle area during sinus rhythm, before any radiofrequency application. We analyzed the QRS morphology of the VAs with and without RBBB during sinus beats. RESULTS: Twenty-four patients (age 59 ± 17 years, female 14) developed RBBB at some point during their procedure. The successful ablation sites of the VAs were the right ventricular outflow tract (RVOT) in 12 patients, pulmonary artery in one, left coronary cusp in five, right coronary cusp in three, right-left cusp junction in two, and great cardiac vein in two. QRS-morphology change was observed in five (20%) cases. The successful ablation sites in that group were the left coronary cusp in three cases, right coronary cusp in one, and RVOT septum in one. The QRS duration of the VAs increased during RBBB. CONCLUSIONS: There are some cases of OT-VAs in which the QRS waveform changes with the appearance of catheter induced RBBB. We need to be aware that when QRS morphology changes during an OT-VA ablation, it does not necessarily mean that the origin or exit of the VA has changed.

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Background and objectives: The frontal QRS-T angle is a novel parameter of myocardial repolarization. Weight gain during pregnancy and physiological changes during a cesarian section may affect the frontal QRS-T angle. We aimed to assess the effect of body mass index (BMI) on the frontal QRS-T angle in pregnant women undergoing cesarean section with spinal anesthesia. Method and materials: This study included 90 pregnant women. BMI was calculated for all pregnant women. The study population was divided into two groups: BMI < 30 (n = 66) and BMI ≥ 30 (n = 24). QT interval measurements and the frontal QRS-T angle were obtained from the report of an electrocardiography machine. Results: It was found that the pre-operative and post-operative frontal QRS-T angle (p = 0.045 and p = 0.007) and QTc interval (p = 0.037 and p < 0.001) were higher in pregnant women with a BMI ≥ 30 than in pregnant women with a BMI < 30. In addition, when compared to pre-operative values, the post-operative frontal QRS-T angle (from 24.0 [20.0-41.5] to 34.5 [19.5-50.0], p = 0.031) and QTc interval (from 420.6 ± 13.3 to 431.7 ± 18.3, p = 0.010) were increased in the BMI ≥ 30 group, whereas no significant post-operative increase was observed in the BMI < 30 group. In correlation analysis, BMI was positively correlated with the frontal QRS-T angle and QTc interval. Conclusions: The frontal QRS-T angle and QTc interval were importantly increased in pregnant women with a BMI ≥ 30 than in pregnant women with a BMI < 30. Also, after cesarean section operation with spinal anesthesia, the frontal QRS-T angle and QTc were increased significantly in the BMI ≥ 30 group, whereas no significant change was observed in the BMI < 30 group. Therefore, it is suggested to perform close post-operative monitoring in pregnant women with a BMI ≥ 30 undergoing cesarean section with spinal anesthesia.

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Aim: to assess the evolution of fragmented QRS (fQRS) and NT-proBNP levels during myocardial infarction (MI).Methods: Among 511 patients, 205 (40.1%) had fQRS, with 54 (26.3%) developing de novo fragmentation during hospitalization.Results: NT-proBNP levels were significantly higher in the fQRS+ group compared with the fQRS- group (1555 vs. 796 pg/ml, p < 0.001). NT-proBNP levels were higher in patients with de novo fragmentation than in those without (2852 vs. 1370 pg/ml, p = 0.011). The incidence of major adverse cardiovascular events was notably higher in fQRS+ patients compared with fQRS- patients (p = 0.001).Conclusion: In acute MI, there was a significant association between fQRS and NT-proBNP levels, with higher NT-proBNP levels observed in those with de novo fQRS compared with those without.

[Box: see text].

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Objective: The cause of syncope is generally determined based on clinical manifestations. There has been little discussion about the value of electrocardiograms for diagnosing neurally mediated syncope. The aim of this study was to test the predictive value of the isolated very low QRS voltage in tilt-table testing for suspected neurally mediated syncope in a Chinese population. Methods: This retrospective study enrolled patients with suspected neurally mediated syncope. Tilt-table testing was a part of the diagnostic examination. Each patient underwent echocardiography and electrocardiogram. isolated very low QRS voltage referred to a voltage of ⩽0.3 mV for the QRS complex in an isolated frontal lead or ⩽0.7 mV for the QRS complex in an isolated precordial lead. Results: In total, 157 patients were included in the tilt-table testing positive group, and 242 patients were included in the tilt-table testing negative group. Compared with the testing negative group, the testing positive group had more patients with isolated very low QRS voltage in the frontal leads (p < 0.001). Moreover, for patients with isolated very low QRS voltage in the precordial leads, no significant difference was noted between the testing positive group and testing negative group (p = 0.289). Isolated very low QRS voltage in the frontal leads demonstrated 84.08% sensitivity and 74.38% specificity for a positive tilt-table testing response. The area under the curve of isolated very low QRS voltage for a positive tilt-table testing response in frontal leads was 0.806 (p < 0.0001). Conclusion: In patients with suspected neurally mediated syncope, isolated very low QRS voltage in the frontal leads is a parameter that can predict a positive tilt-table testing response. The presence of isolated very low QRS voltage in frontal leads can serve as a parameter for evaluating syncope patients.

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BACKGROUND: Premature ventricular contractions (PVCs) are common arrhythmias with diverse clinical implications. This retrospective study aimed to evaluate the efficacy of medical treatments using various clinical, imaging, and electrocardiographic parameters in patients with idiopathic PVCs. METHODS: A total of 1051 patients with idiopathic PVCs were retrospectively analyzed. Patients were categorized into three groups based on treatment response: beta-blocker (BB) responders (479 patients), calcium-channel blocker (CCB) responders (335 patients), and class 1c antiarrhythmic (AA) responders (237 patients). Clinical, imaging, and electrocardiographic data were collected and analyzed to assess the factors influencing treatment response. RESULTS: Age, left ventricular ejection fraction (LVEF), PVC QRS duration, CI variability, and multiple PVC morphologies were identified as significant factors affecting treatment response. Older age and lower LVEF were associated with better response to BB treatment, whereas CCB responders showed narrower QRS complexes. BB responders also exhibited higher CI variability, possibly linked to automaticity mechanisms. Moreover, the BB responder group had a higher frequency of multiple PVC morphologies. CONCLUSION: These findings emphasize the importance of tailored treatment approaches based on individual patient characteristics.

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An electrocardiogram of an uncommon congenital heart disease is presented to highlight the unique findings in diagnosis with its clinical implications and predictive value.

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INTRODUCTION: Abnormal QRS-T angles are prognostic markers for cardiovascular deaths including sudden cardiac death. They occur in ∼5-6% of population-based cohorts but in ∼20% of patients with diabetes. The mechanistic background, electrical activation and/or recovery disturbances, is not known and the topic of this study. METHODS: Applying Frank vectorcardiography (VCG) and simultaneously recorded scalar 12­lead ECG, electrical activation and recovery of abnormal QRS-T angles were studied in 311 participants (5.4%) from a population-based cohort of 5796 women and men in the main Swedish CArdio-Pulmonary bio-Imaging Study (SCAPIS) in Gothenburg. Cut-off values for the peak and mean QRS-T angles were > 124° and > 119°, based on the >95th percentile among all 1080 participants in the pilot SCAPIS and reference values for normal directions (Q1-Q3) from 319 apparently healthy (30%) of them. RESULTS: Of 311 cases 17% had known cardiac disease. Deviations of QRS and QRSarea-vectors from reference limits (90%) were significantly more common than deviations of T- and Tarea-vectors (65%). Standard ECG signs suggested pathophysiology in 20%; left bundle branch block (LBBB) and voltage criteria for left ventricular hypertrophy being most frequent (9-10%) each. Sub-group analysis of the 30 with LBBB showed very large variability in vector directions. CONCLUSIONS: Our observations provide mechanistic insights about abnormal QRS-T angles of potential value for future prognostic and interventional studies. The results also have potential implications for LBB area pacing and the approach to left ventricular hypertrophy.

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