The evaluation of the short-term and long-term hydroxychloroquine therapy on ECG parameters.

Amidst the COVID-19 pandemic, hydroxychloroquine (HCQ) was widely administered despite limited data on its safety and efficacy. This study assesses the acute and chronic impacts of HCQ on electrocardiography (ECG) parameters alongside the effects of azithromycin and levofloxacin coadministration in patients with COVID-19. A comprehensive analysis was conducted on 109 COVID-19 patients receiving HCQ, with or without Azithromycin and/or Levofloxacin, and 51 long-term HCQ-treated Sjogren's syndrome (SS) patients. ECG parameters, including QTc interval, were meticulously evaluated against a control group of 109 COVID-19 patients without HCQ treatment. HCQ monotherapy, in combination with Levofloxacin, significantly prolonged the QTc interval in COVID-19 patients compared to controls. Notably, the combination of HCQ and Azithromycin demonstrated a mitigated impact on QTc prolongation. Long-term HCQ use in SS patients did not significantly affect QTc intervals, illustrating a distinct safety profile from short-term use in COVID-19 treatment. HCQ's impact on QTc prolongation is influenced by therapeutic context, coadministered drugs, and patient demographics. The findings underscore the necessity of cautious HCQ use, particularly in acute settings like COVID-19, where monitoring and consideration of drug interactions and patient-specific factors are critical.

Drug-induced QT interval prolongation in patients with heart failure with preserved ejection fraction.

Heart failure (HF) with reduced ejection fraction (HFrEF) is a risk factor for drug-induced QT interval prolongation. It is unknown if HF with preserved ejection fraction (HFpEF) is also associated with an increased risk. Dofetilide and sotalol are potent QT interval-prolonging agents that are frequently used in patients with HFpEF, in whom atrial fibrillation is a common comorbidity. We tested the hypothesis that the risk of QT interval prolongation associated with dofetilide and sotalol is increased in patients with HFpEF. We conducted a retrospective cohort study conducted using electronic health records from the Indiana Network for Patient Care (January 31, 2010 -May 3, 2021). After removing patients with overlapping diagnoses of HFpEF and HFrEF, no diagnosis code, and absence of QT interval records, we identified patients taking dofetilide or sotalol among three groups: HFrEF (n = 138), HFpEF (n = 109), and no HF (n = 729). QT prolongation was defined as heart rate-corrected QT (QTc) > 500 ms during dofetilide/sotalol therapy. Unadjusted odds ratios (OR) for QT prolongation were determined by univariate analysis. Adjusted ORs were determined by generalized estimating equations (GEE) with logit link to account for an individual cluster with different times of hospitalization and covariates. QTc prolongation associated with dofetilide or sotalol occurred in 53.2%, 71.7% and 30.0% of patients with HFpEF, HFrEF, and patients with no HF, respectively. After adjusting for age, sex, race, serum potassium and magnesium concentrations, kidney function, concomitant drug therapy, and comorbid conditions, the adjusted odds of QTc prolongation were significantly higher in patients with HFpEF [OR = 1.98 (95% CI 1.17-3.33)], and in those with HFrEF [OR = 5.23, (3.15-8.67)], compared to those with no evidence of HF. The odds of QT prolongation among inpatients receiving dofetilide or sotalol were increased in patients with HFpEF and HFrEF compared to those who did not have HF.

[Genetic and clinical characteristics of single and compound types of patients with long QT syndrome type 3].

Objective: To explore the genetic background and clinical features of patients with long QT syndrome type 3 (LQT3). Methods: This retrospective cohort included patients diagnosed with LQT3 at the Department of Cardiology, Renmin Hospital of Wuhan University from January 1998 to December 2022. Patients were categorized into compound type group and single type group based on the presence of a single SCN5A mutation. The two groups were followed up and the differences in baseline characteristics, electrocardiograms, and clinical events between the two groups and probands were compared. Kaplan-Meier curves were used for survival analysis, and the log-rank test was employed to compare the event-free survival rates of first cardiac events between the groups and probands. Results: A total of 97 LQT3 patients were enrolled, including 59 probands. The age at diagnosis was (23.45±19.86) years, with 46 patients (47.4%) being male. Among them, 89 patients were classified as single type group, while 8 patients were classified as compound type group. Genetic testing identified 49 SCN5A mutations, with missense mutations being the majority (91.8%), primarily located in transmembrane regions (40.8%, n=20), interdomain linker regions (28.6%, n=14), and C-terminus (22.4%, n=11). The first cardiac event occurred in 44 patients (45.4%), with an onset age of (13.82±12.50) years. The main trigger was identified as rest or sleep (54.5%, n=24). Compared with patients in single type group, patients in compound type group were younger at diagnosis ((10.35±10.28) years vs. (24.63±20.13) years, P=0.040), had a significantly higher proportion of syncope (87.5% (7/8) vs. 33.7% (30/89), P=0.009), aborted cardiac arrest (62.5% (5/8) vs. 11.2% (10/89), P=0.001), and a lower incidence of event-free survival rates of first cardiac events (12.5% (1/8) vs.58.4% (52/89), log-rank P=0.001). The probands in compound type group had a significantly higher proportion of aborted cardiac arrest comparing to probands in single type group (62.5% (5/8) vs. 17.6% (9/51), P=0.020), while the difference in the incidence rate of event-free survival rates of first cardiac events between the probands in two groups was not statistically significant (12.5% (1/8) vs. 39.2% (20/51), log-rank P=0.08). Conclusion: Compound type LQT3 patients are not uncommon. Such patients are diagnosed at a younger age and exhibit more severe phenotypes, requiring close follow-up and proactive intervention strategies.

Vigorous Exercise in Patients With Congenital Long QT Syndrome: Results of the Prospective, Observational, Multinational LIVE-LQTS Study.

BACKGROUND: Whether vigorous exercise increases risk of ventricular arrhythmias for individuals diagnosed and treated for congenital long QT syndrome (LQTS) remains unknown. METHODS: The National Institutes of Health-funded LIVE-LQTS study (Lifestyle and Exercise in the Long QT Syndrome) prospectively enrolled individuals 8 to 60 years of age with phenotypic and/or genotypic LQTS from 37 sites in 5 countries from May 2015 to February 2019. Participants (or parents) answered physical activity and clinical events surveys every 6 months for 3 years with follow-up completed in February 2022. Vigorous exercise was defined as ≥6 metabolic equivalents for >60 hours per year. A blinded Clinical Events Committee adjudicated the composite end point of sudden death, sudden cardiac arrest, ventricular arrhythmia treated by an implantable cardioverter defibrillator, and likely arrhythmic syncope. A National Death Index search ascertained vital status for those with incomplete follow-up. A noninferiority hypothesis (boundary of 1.5) between vigorous exercisers and others was tested with multivariable Cox regression analysis. RESULTS: Among the 1413 participants (13% <18 years of age, 35% 18-25 years of age, 67% female, 25% with implantable cardioverter defibrillators, 90% genotype positive, 49% with LQT1, 91% were treated with beta-blockers, left cardiac sympathetic denervation, and/or implantable cardioverter defibrillator), 52% participated in vigorous exercise (55% of these competitively). Thirty-seven individuals experienced the composite end point (including one sudden cardiac arrest and one sudden death in the nonvigorous group, one sudden cardiac arrest in the vigorous group) with overall event rates at 3 years of 2.6% in the vigorous and 2.7% in the nonvigorous exercise groups. The unadjusted hazard ratio for experience of events for the vigorous group compared with the nonvigorous group was 0.97 (90% CI, 0.57-1.67), with an adjusted hazard ratio of 1.17 (90% CI, 0.67-2.04). The upper 95% one-sided confidence level extended beyond the 1.5 boundary. Neither vigorous or nonvigorous exercise was found to be superior in any group or subgroup. CONCLUSIONS: Among individuals diagnosed with phenotypic and/or genotypic LQTS who were risk assessed and treated in experienced centers, LQTS-associated cardiac event rates were low and similar between those exercising vigorously and those not exercising vigorously. Consistent with the low event rate, CIs are wide, and noninferiority was not demonstrated. These data further inform shared decision-making discussions between patient and physician about exercise and competitive sports participation. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02549664.

Thorough QT/QTc study to evaluate the effect of a single supratherapeutic dose of islatravir on QTc interval prolongation in healthy adults.

Islatravir is a deoxynucleoside analog being developed for the treatment of HIV-1 infection. Clinical studies are being conducted to evaluate islatravir, administered in combination with other antiretroviral therapies, at doses of 0.25 mg once daily and 2 mg once weekly. In multiple previous clinical studies, islatravir was generally well tolerated, with no clear trend in cardiac adverse events. A trial was conducted to evaluate the effect of islatravir on cardiac repolarization. A randomized, double-blind, active- and placebo-controlled phase 1 trial was conducted, in which a single dose of islatravir 0.75 mg, islatravir 240 mg (supratherapeutic dose), moxifloxacin 400 mg (active control), or placebo was administered. Continuous 12-lead electrocardiogram monitoring was performed before dosing through 24 hours after dosing. QT interval measurements were collected, and safety and pharmacokinetics were evaluated. Sixty-three participants were enrolled, and 59 completed the study. Fridericia's QT correction for heart rate was inadequate; therefore, a population-specific correction was applied (QTcP). The placebo-corrected change from baseline in QTcP (ΔΔQTcP) interval at the observed geometric mean maximum plasma concentration associated with islatravir 0.75 mg and islatravir 240 mg was <10 ms at all time points. Assay sensitivity was confirmed because the use of moxifloxacin 400 mg led to a ΔΔQTcP >10 ms. The pharmacokinetic profile of islatravir was consistent with that of previous studies, and islatravir was generally well tolerated. Results from the current trial suggest that single doses of islatravir as high as 240 mg do not lead to QTc interval prolongation.

Variant patterns of electrical activation and recovery in normal human hearts revealed by noninvasive electrocardiographic imaging.

AIMS: Although electrical activity of the normal human heart is well characterized by the electrocardiogram, detailed insights into within-subject and between-subject variations of ventricular activation and recovery by noninvasive electroanatomic mapping are lacking. We characterized human epicardial activation and recovery within and between normal subjects using non-invasive electrocardiographic imaging (ECGI) as a basis to better understand pathology. METHODS AND RESULTS: Epicardial activation and recovery were assessed by ECGI in 22 normal subjects, 4 subjects with bundle branch block (BBB) and 4 with long-QT syndrome (LQTS). We compared characteristics between the ventricles [left ventricle (LV) and right ventricle (RV)], sexes, and age groups (<50/≥50years). Pearson's correlation coefficient (CC) was used for within-subject and between-subject comparisons. Age of normal subjects averaged 49 ± 14 years, 6/22 were male, and no structural/electrical heart disease was present. The average activation time was longer in LV than in RV, but not different by sex or age. Electrical recovery was similar for the ventricles, but started earlier and was on average shorter in males. Median CCs of between-subject comparisons of the ECG signals, activation, and recovery patterns were 0.61, 0.32, and 0.19, respectively. Within-subject beat-to-beat comparisons yielded higher CCs (0.98, 0.89, and 0.82, respectively). Activation and/or recovery patterns of patients with BBB or LQTS contrasted significantly with those found in the normal population. CONCLUSION: Activation and recovery patterns vary profoundly between normal subjects, but are stable individually beat to beat, with a male preponderance to shorter recovery. Individual characterization by ECGI at baseline serves as reference to better understand the emergence, progression, and treatment of electrical heart disease.

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.

Establishment of human embryonic stem cell lines carrying LQT1 mutations by CRISPR base editing.

The KCNQ1 gene encodes a voltage-gated potassium channel required for cardiac action potentials. Mutations in this gene have been associated with hereditary long QT syndrome 1, Jervell and Lange-Nielsen syndromes, and familial atrial fibrillation. The NM_000218.3(KCNQ1): c.604 + 2T > C mutation has been categorized as the causative variant leading to LQT1. In this study, we generated a KCNQ1 (c.644 + 2T > C) mutation human embryonic stem cell line WAe009-A-1L based on CRISPR base editing system. WAe009-A-1L cell has the potential to differentiate cardiomyocytes and would be used as an in vitro disease model for mechanism exploration and drug screening.

Single Construct Suppression and Replacement Gene Therapy for the Treatment of All CALM1-, CALM2-, and CALM3-Mediated Arrhythmia Disorders.

BACKGROUND: CaM (calmodulin)-mediated long-QT syndrome is a genetic arrhythmia disorder (calmodulinopathies) characterized by a high prevalence of life-threatening ventricular arrhythmias occurring early in life. Three distinct genes (CALM1, CALM2, and CALM3) encode for the identical CaM protein. Conventional pharmacotherapies fail to adequately protect against potentially lethal cardiac events in patients with calmodulinopathy. METHODS: Five custom-designed CALM1-, CALM2-, and CALM3-targeting short hairpin RNAs (shRNAs) were tested for knockdown (KD) efficiency using TSA201 cells and reverse transcription-quantitative polymerase chain reaction. A dual-component suppression and replacement (SupRep) CALM gene therapy (CALM-SupRep) was created by cloning into a single construct CALM1-, CALM2-, and CALM3-specific shRNAs that produce KD (suppression) of each respective gene and a shRNA-immune CALM1 cDNA (replacement). CALM1-F142L, CALM2-D130G, and CALM3-D130G induced pluripotent stem cell-derived CMs were generated from patients with CaM-mediated long-QT syndrome. A voltage-sensing dye was used to measure action potential duration at 90% repolarization (APD90). RESULTS: Following shRNA KD efficiency testing, a candidate shRNA was identified for CALM1 (86% KD), CALM2 (71% KD), and CALM3 (94% KD). The APD90 was significantly prolonged in CALM2-D130G (647±9 ms) compared with CALM2-WT (359±12 ms; P<0.0001). Transfection with CALM-SupRep shortened the average APD90 of CALM2-D130G to 457±19 ms (66% attenuation; P<0.0001). Additionally, transfection with CALM-SupRep shortened the APD90 of CALM1-F142L (665±9 to 410±15 ms; P<0.0001) and CALM3-D130G (978±81 to 446±6 ms; P<0.001). CONCLUSIONS: We provide the first proof-of-principle suppression-replacement gene therapy for CaM-mediated long-QT syndrome. The CALM-SupRep gene therapy shortened the pathologically prolonged APD90 in CALM1-, CALM2-, and CALM3-variant CaM-mediated long-QT syndrome induced pluripotent stem cell-derived CM lines. The single CALM-SupRep construct may be able to treat all calmodulinopathies, regardless of which of the 3 CaM-encoding genes are affected.

Generating a human induced pluripotent stem cell line (XACHi018-A) from a Timothy syndrome infant carrying heterozygous CACNA1C c.1216G>A (p.G406R) mutation.

Timothy syndrome, an extremely rare disease, is closely associated with a mutation in CACNA1C gene, which encodes the cardiac L-type voltage-gated calcium channel (Cav1.2). In this study, we generated a human induced pluripotent stem cell (iPSC) line from a Timothy syndrome infant carrying heterozygous CACNA1C mutation (transcript variant NM_000719.7c.1216G>A: p.G406R). The generated iPSC line showed typical stem cell morphology, positively expressed pluripotency and proliferation markers, normal karyotype, and trilineage differentiation potential. Therefore, this patient-specific iPSC can be of great significance in investigating the mechanisms underlying Timothy syndrome, and hence establishing effective intervention strategies.

The Use of Drugs that Should be Avoided or Used with Caution in Patients Hospitalized for Acute Decompensated Heart Failure.

BACKGROUND: Heart failure (HF) is a pervasive global health concern, with acute decompensated heart failure (ADHF) contributing significantly to morbidity and mortality. Medications used in patients with HF may exacerbate HF or prolong the QT interval, posing additional risks. OBJECTIVE: The objective is to assess the prevalence and utilization patterns of medications known to cause or exacerbate HF and prolong the QT interval among patients with ADHF. Understanding these patterns is crucial for optimizing patient care and minimizing potential risks. METHODS: A retrospective chart review was conducted at Huntsville Hospital, Huntsville, USA, covering 602 patients with ADHF over a 40-month period. Inclusion criteria involved age ≥ 18 years, a history of HF, and ADHF admission. The 2016 American Heart Association Scientific Statement was used to identify drugs that may cause or exacerbate HF and those that could prolong the QT interval RESULTS: Among the 602 patients, 57.3% received medications causing or exacerbating HF, notably albuterol (34.9%) and diabetes medications (20.4%), primarily metformin, followed by urologic agents (14.3%), mostly tamsulosin, and nonsteroidal anti-inflammatory drugs (NSAIDs) (6.1%). Moreover, 82.9% were on medications prolonging the QT interval, with loop diuretics, amiodarone, ondansetron, and famotidine most prevalent. Furthermore, 42.1% of the patients received more than two concomitant medications that prolong the QT interval, which can further exacerbate the risk of torsades de pointes. CONCLUSION: This study underscores the high prevalence of HF-causing or HF-exacerbating medications and QT-prolonging drugs in patients with ADHF. Healthcare professionals must be cognizant of these patterns, advocating for safer prescribing practices to optimize patient outcomes and reduce the burden of HF-related hospitalizations.

Transmural APD heterogeneity determines ventricular arrhythmogenesis in LQT8 syndrome: Insights from Bidomain computational modeling.

Long QT Syndrome type 8 (LQT8) is a cardiac arrhythmic disorder associated with Timothy Syndrome, stemming from mutations in the CACNA1C gene, particularly the G406R mutation. While prior studies hint at CACNA1C mutations' role in ventricular arrhythmia genesis, the mechanisms, especially in G406R presence, are not fully understood. This computational study explores how the G406R mutation, causing increased transmural dispersion of repolarization, induces and sustains reentrant ventricular arrhythmias. Using three-dimensional numerical simulations on an idealized left-ventricular model, integrating the Bidomain equations with the ten Tusscher-Panfilov ionic model, we observe that G406R mutation with 11% and 50% heterozygosis significantly increases transmural dispersion of repolarization. During S1-S4 stimulation protocols, these gradients facilitate conduction blocks, triggering reentrant ventricular tachycardia. Sustained reentry pathways occur only with G406R mutation at 50% heterozygosis, while neglecting transmural heterogeneities of action potential duration prevents stable reentry, regardless of G406R mutation presence.

[Cardiac channelopathies in the context of hereditary arrhythmia syndromes]. / Kardiale Kanalopathien im Kontext hereditärer Arrhythmiesyndrome.

Genetic arrhythmia disorders are rare diseases; however, they are a common cause of sudden cardiac death in children, adolescents, and young adults. In principle, a distinction can be made between channelopathies and cardiomyopathies in the context of genetic diseases. This paper focuses on the channelopathies long and short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT). Early diagnosis of these diseases is essential, as drug therapy, behavioral measures, and if necessary, implantation of a cardioverter defibrillator can significantly improve the prognosis and quality of life of patients. This paper highlights the pathophysiological and genetic basis of these channelopathies, describes their clinical manifestations, and comments on the principles of diagnosis, risk stratification and therapy.

Feasibility and accuracy of mobile QT interval monitoring strategies in bedaquiline-enhanced prophylactic leprosy treatment.

Some anti-mycobacterial drugs are known to cause QT interval prolongation, potentially leading to life-threatening ventricular arrhythmia. However, the highest leprosy and tuberculosis burden occurs in settings where electrocardiographic monitoring is challenging. The feasibility and accuracy of alternative strategies, such as the use of automated measurements or a mobile electrocardiogram (mECG) device, have not been evaluated in this context. As part of the phase II randomized controlled BE-PEOPLE trial evaluating the safety of bedaquiline-enhanced post-exposure prophylaxis (bedaquiline and rifampicin, BE-PEP, versus rifampicin, SDR-PEP) for leprosy, all participants had corrected QT intervals (QTc) measured at baseline and on the day after receiving post-exposure prophylaxis. The accuracy of mECG measurements as well as automated 12L-ECG measurements was evaluated. In total, 635 mECGs from 323 participants were recorded, of which 616 (97%) were of sufficient quality for QTc measurement. Mean manually read QTc on 12L-ECG and mECG were 394 ± 19 and 385 ± 18 ms, respectively (p < 0.001), with a strong correlation (r = 0.793). The mean absolute QTc difference between both modalities was 11 ± 10 ms. Mean manual and automated 12L-ECG QTc were 394 ± 19 and 409 ± 19 ms, respectively (n = 636; p < 0.001), corresponding to moderate agreement (r = 0.655). The use of a mECG device for QT interval monitoring was feasible and yielded a median absolute QTc error of 8 ms. Automated QTc measurements were less accurate, yielding longer QTc intervals.