Effect of serum electrolytes within normal ranges on QTc prolongation: a cross-sectional study in a Chinese rural general population

The role of mitochondrial dysfunction in the association between trace metals and QTc prolongation in the aged population

This study delves into the relationship between environmental metal exposure and QT interval corrected for heart rate (QTc) prolongation, a critical marker for cardiovascular risk in the elderly. Although the interplay between metal exposure and QTc prolongation is important for predicting sudden cardiac death, it remains underexplored. Our analysis of 6478 participants from the Shenzhen aging-related disorder cohort involved measuring urinary concentrations of 22 trace metals and using mitochondrial DNA copy number (mtDNA-CN) as an indicator of mitochondrial dysfunction. Utilizing Bayesian kernel machine regression, and structural equation modeling, we assessed the effects of mixed trace metals on QTc prolongation. Our findings indicated a direct association between certain metals (Sb, Cu, Zn) and a 7 % increase in QTc prolongation risk, while Li, V, and Rb were associated with a 5 % reduction in risk. Elevated levels of V, Ti, and Cr corresponded to higher mtDNA-CN. Notably, restricted cubic splines revealed a U-shaped, nonlinear relationship between mtDNA-CN and QTc prolongation. After adjusting for metal exposure, an inverse correlation was observed between mtDNA-CN and QTc prolongation, suggesting mitochondrial dysfunction as a partial mediator.

Clinical research progress of novel antituberculosis drugs on multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) has become a critical challenge to public health, and the prevention and treatment of MDR-TB are of great significance in reducing the global burden of tuberculosis. How to improve the effectiveness and safety of chemotherapy for MDR-TB is a pressing issue that needs to be addressed in tuberculosis control efforts. This article provides a comprehensive review of the clinical application of new antituberculosis drugs in MDR-TB, aiming to provide a scientific basis for the prevention and treatment strategy of MDR-TB.

Life-Threatening Cardiac Arrhythmias in a Case of Undetected Myxedema Coma: Importance of Early Detection and Medication Adherence

BACKGROUND Myxedema coma is a rare, life-threatening condition caused by a severe form of hypothyroidism. The dangerously low levels of circulating thyroid hormone can lead to progressive mental status changes and numerous organ dysfunctions, including serious cardiac abnormalities. CASE REPORT We present a case of a 59-year-old woman who presented with altered mental status and fall who was originally thought to have a cerebrovascular accident but was later diagnosed with myxedema coma, after multiple cardiac arrests. It was discovered that the patient had not been taking any of her medications for the last several weeks, after her primary care provider retired from practice. Initial laboratory evaluation was significant for a TSH level of 159.419 mIU/L and an undetectable free T4 level. Complications of the myxedema coma resulted in QTC interval prolongation, causing torsades de pointes and sustained polymorphic ventricular tachycardia, requiring cardioversion. CONCLUSIONS This case demonstrates the importance of early detection and treatment of myxedema coma, as it can cause life-threatening cardiac arrhythmias. It also emphasizes the need to ensure proper medication adherence in patients with chronic medical conditions, as non-compliance can result in dire consequences.

DIALIZE China: A Phase IIIb, Randomized, Placebo-Controlled Study to Reduce Predialysis Hyperkalemia With Sodium Zirconium Cyclosilicate in Chinese Patients

PURPOSE

The DIALIZE China study (Reduce Incidence of Pre-Dialysis Hyperkalaemia With Sodium Zirconium Cyclosilicate in Chinese Subjects) (NCT04217590) evaluated sodium zirconium cyclosilicate (SZC) for the management of hyperkalemia in Chinese patients undergoing hemodialysis.

METHODS

In the double-blind, Phase IIIb DIALIZE China study, Chinese adults with kidney failure and predialysis hyperkalemia (predialysis serum potassium [sK+] concentration >5.4 mmol/L after the long interdialytic interval [LIDI] and >5.0 mmol/L after ≥1 short interdialytic interval) who were receiving hemodialysis 3 times weekly were randomized to placebo or SZC 5 g once daily on nondialysis days. Doses were titrated towards maintaining normokalemia for 4 weeks (titration period) in 5-g increments up to 15 g. Primary efficacy was the proportion of responders during the 4-week evaluation period following the titration period (ie, those with a predialysis sK+ of 4.0-5.0 mmol/L for at least 3 of 4 hemodialysis visits following the LIDI) who did not require urgent rescue therapy.

FINDINGS

Overall, 134 adults (mean [SD] age, 55 [11.3] years) were randomized to SZC or placebo (n = 67 each). There were significantly more responders with SZC (37.3%) versus placebo (10.4%; estimated odds ratio [OR] = 5.10; 95% CI, 1.90-15.12; P < 0.001). The probability of all predialysis sK+ concentrations being 3.5 to 5.5 mmol/L was significantly higher with SZC versus placebo (estimated OR = 6.41; 95% CI, 2.71-15.12; P < 0.001). A greater proportion of patients achieved an sK+ of 3.5 to 5.5 mmol/L on at least 3 of 4 LIDI visits during evaluation with SZC (73.1%) versus placebo (29.9%). Serious adverse events occurred in 9.1% and 11.9% of patients in the SZC and placebo groups, respectively.

IMPLICATIONS

SZC treatment for predialysis hyperkalemia is effective and well tolerated in Chinese patients with kidney failure receiving hemodialysis.

CLINICALTRIALS

gov identifier: NCT04217590.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Scoping review: QT interval prolongation in regimen containing bedaquiline and delamanid in patients with drug-resistant tuberculosis

Background

A regimen containing bedaquiline-delamanid is recommended in management of drug-resistant tuberculosis (DR TB) to increase a success rate. However, this regimen was rare in a clinical setting due to a potential risk of QT prolongation. Several studies have reported the incidence of QT prolongation after administration of this regimen, but the results are inconsistent due to different sample size, study design, and covariate. The aim of this review is to summarize and analyze the published articles related to QT prolongation of bedaquiline and delamanid in PubMed and ScienceDirect databases using a scoping review.

Methods

This scoping review was conducted under PRISMA for scoping review. The outcomes of this review were incidence of QT prolongation and death. We found 8 articles to be included in this review.

Results

The incidence of QT prolongation was higher for DR TB patients who received a regimen containing bedaquiline and delamanid. However, this review found no clinical symptoms, such as cardiac arrhythmias, torsade de pointes, or even death. DR TB patients, especially the elderly, were at risk for QT prolongation. Special consideration in patients with HIV and low level of potassium should be closely monitored for QT interval.

Conclusion

The regular measurement of electrocardiography was highly recommended to evaluate QT interval. Generally, the use of individualized regimen containing bedaquiline and delamanid is relatively safe in DR TB patients.

Declining Levels and Bioavailability of IGF-I in Cardiovascular Aging Associate With QT Prolongation-Results From the 1946 British Birth Cohort

Background

As people age, circulating levels of insulin-like growth factors (IGFs) and IGF binding protein 3 (IGFBP-3) decline. In rat cardiomyocytes, IGF-I has been shown to regulate sarcolemmal potassium channel activity and late sodium current thus impacting cardiac repolarization and the heart rate-corrected QT (QTc). However, the relationship between IGFs and IGFBP-3 with the QTc interval in humans, is unknown.

Objectives

To examine the association of IGFs and IGFBP-3 with QTc interval in an older age population-based cohort.

Methods

Participants were from the 1946 Medical Research Council (MRC) National Survey of Health and Development (NSHD) British birth cohort. Biomarkers from blood samples at age 53 and 60-64 years (y, exposures) included IGF-I/II, IGFBP-3, IGF-I/IGFBP-3 ratio and the change (Δ) in marker levels between the 60-64 and 53y sampled timepoints. QTc (outcome) was recorded from electrocardiograms at the 60-64y timepoint. Generalized linear multivariable models with adjustments for relevant demographic and clinical factors, were used for complete-cases and repeated after multiple imputation.

Results

One thousand four hundred forty-eight participants were included (48.3% men; QTc mean 414 ms interquartile range 26 ms). Univariate analysis revealed an association between low IGF-I and IGF-I/IGFBP-3 ratio at 60-64y with QTc prolongation [respectively: β -0.30 ms/nmol/L, (95% confidence intervals -0.44, -0.17), p < 0.001; β-28.9 ms/unit (-41.93, -15.50), p < 0.001], but not with IGF-II or IGFBP-3. No association with QTc was found for IGF biomarkers sampled at 53y, however both ΔIGF-I and ΔIGF-I/IGFBP-3 ratio were negatively associated with QTc [β -0.04 ms/nmol/L (-0.08, -0.008), p = 0.019; β -2.44 ms/unit (-4.17, -0.67), p = 0.007] while ΔIGF-II and ΔIGFBP-3 showed no association. In fully adjusted complete case and imputed models (reporting latter) low IGF-I and IGF-I/IGFBP-3 ratio at 60-64y [β -0.21 ms/nmol/L (-0.39, -0.04), p = 0.017; β -20.14 ms/unit (-36.28, -3.99), p = 0.015], steeper decline in ΔIGF-I [β -0.05 ms/nmol/L/10 years (-0.10, -0.002), p = 0.042] and shallower rise in ΔIGF-I/IGFBP-3 ratio over a decade [β -2.16 ms/unit/10 years (-4.23, -0.09), p = 0.041], were all independently associated with QTc prolongation. Independent associations with QTc were also confirmed for other previously known covariates: female sex [β 9.65 ms (6.65, 12.65), p < 0.001], increased left ventricular mass [β 0.04 ms/g (0.02, 0.06), p < 0.001] and blood potassium levels [β -5.70 ms/mmol/L (-10.23, -1.18) p = 0.014].

Conclusion

Over a decade, in an older age population-based cohort, declining levels and bioavailability of IGF-I associate with prolongation of the QTc interval. As QTc prolongation associates with increased risk for sudden death even in apparently healthy people, further research into the antiarrhythmic effects of IGF-I on cardiomyocytes is warranted.

How safe are children with COVID-19 from cardiac risks? Pediatric risk assesment; insights from echocardiography and electrocardiography

Background/aim

Approximately 40 million individuals worldwide have been infected with SARS-CoV-2, the virus responsible for the novel coronavirus disease-2019 (COVID-19). Despite the current literature about the cardiac effects of COVID-19 in children, more information is required. We aimed to determine both cardiovascular and arrhythmia assessment via electrocardiographic and echocardiographic parameters.

Materials and methods

We evaluated seventy children who were hospitalized with COVID-19 infections and seventy children as normal control group through laboratory findings, electrocardiography (ECG), and transthoracic echocardiography (TTE).

Results

We observed significantly increased levels of Tp-Te, Tp-Te/QT, and Tp-Te/QTc compared with the control group. Twenty-five of 70 (35.7%) patients had fragmented QRS (fQRS) without increased troponin levels. On the other hand, none of the patients had pathologic corrected QT(QTc) prolongation during the illness or its treatment. On TTE, 20 patients had mild mitral insufficiency, among whom only five had systolic dysfunction (ejection fraction < 55%). There was no significant difference between the patient and control groups, except for isovolumic relaxation time (IVRT) in terms of mean systolic and diastolic function parameters. IVRT of COVID patients was significantly lower than that of control group.

Conclusion

Despite all the adult studies, the effects of COVID‐19 on myocardial function are not well established in children. The thought that children are less affected by the illness may be a misconception.

Assessment of Hypertension Using Clinical Electrocardiogram Features: A First-Ever Review

Hypertension affects an estimated 1.4 billion people and is a major cause of morbidity and mortality worldwide. Early diagnosis and intervention can potentially decrease cardiovascular events later in life. However, blood pressure (BP) measurements take time and require training for health care professionals. The measurements are also inconvenient for patients to access, numerous daily variables affect BP values, and only a few BP readings can be collected per session. This leads to an unmet need for an accurate, 24-h continuous, and portable BP measurement system. Electrocardiograms (ECGs) have been considered as an alternative way to measure BP and may meet this need. This review summarizes the literature published from January 1, 2010, to January 1, 2020, on the use of only ECG wave morphology to monitor BP or identify hypertension. From 35 articles analyzed (9 of those with no listed comorbidities and confounders), the P wave, QTc intervals and TpTe intervals may be promising for this purpose. Unfortunately, with the limited number of articles and the variety of participant populations, we are unable to make conclusions about the effectiveness of ECG-only BP monitoring. We provide 13 recommendations for future ECG-only BP monitoring studies and highlight the limited findings in pregnant and pediatric populations. With the advent of convenient and portable ECG signal recording in smart devices and wearables such as watches, understanding how to apply ECG-only findings to identify hypertension early is crucial to improving health outcomes worldwide.

Effect of Methadone or Hydromorphone on Cardiac Conductivity in Dogs Before and During Sevoflurane Anesthesia

Objective: To evaluate changes in electrocardiogram (ECG) variables in healthy dogs receiving either methadone or hydromorphone IV before and during sevoflurane anesthesia. Study Design: Prospective clinical study. Animals: Forty client-owned dogs. Methods: Dogs were randomized to receive methadone 0.5 mg/kg IV or hydromorphone 0.1 mg/kg IV in each part of a two-part study. In part one, dogs received the opioid prior to sevoflurane anesthesia (groups MS, n = 12 and HS, n = 12). Anesthesia was induced with propofol IV, maintained with sevoflurane, and dogs were mechanically ventilated. Standard 6-lead ECG recordings were obtained before opioid administration, 2, 5, and 10 min after opioid administration prior to anesthesia, and during anesthesia 15 min after end-tidal sevoflurane stabilized at 2.4%. In part two, conscious dogs received the same opioid treatments and ECGs were obtained at equivalent time points without undergoing anesthesia (groups M, n = 8 and H, n = 8). Values for ECG variables were determined by a blinded cardiologist and included: Heart rate (HR), PR interval, QT interval, and HR corrected QT interval (QTc) using the Bazett (QTcB), Fridericia (QTcF), and Van de Water (QTcV) formulas. Differences over time and between all four groups were evaluated using ANOVA for repeated measures with significance set at p ≤ 0.05. Results: Both methadone and hydromorphone administration reduced HR and prolonged PR and QT intervals, with greater changes observed during sevoflurane anesthesia. The greatest prolongation in QT interval was observed in dogs administered methadone during sevoflurane anesthesia. Conclusions and Clinical Relevance: Methadone and hydromorphone caused disturbances in myocardial electrical activity, and the addition of sevoflurane enhanced these disturbances. Both drugs caused considerable QT interval prolongation into the proarrhythmogenic range, with methadone causing greater prolongation.

Predictive factors for cardiac conduction abnormalities with hydroxychloroquine-containing combinations for COVID-19

This longitudinal, prospective cohort study aimed to assess risk of QTc interval prolongation and its predicting factors in subjects treated with combinations containing hydroxychloroquine (HCQ) for COVID-19. Moderate-to-severe QTc prolongation during therapy was defined as a QTc interval >470 ms in men or >480 ms in women. Patients were treated under strict cardiac supervision. A total of 105 adults were included [56% male; median (IQR) age 69 (57-79) years]. All patients received therapy with HCQ in combination with azithromycin (AZM), and 95 (90%) also with lopinavir/ritonavir (LPV/r). Concomitant medications classified as having risk of developing torsades de pointes (TdP) were simultaneously used in 81 patients (77%). Moderate-to-severe QTc prolongation was observed in 14 patients (13%), mostly at Days 3-5 from baseline, with 6 (6%) developing severe prolongation (>500 ms). There was no evidence of TdP arrhythmia or TdP-associated death. Adding LPV/r to HCQ+AZM did not significantly prolong the QTc interval. Multivariable Cox regression revealed that comedications with known risk of TdP (HR = 11.28, 95% CI 1.08-117.41), higher neutrophil-to-lymphocyte (NLR) ratio (HR = 1.10, 95% CI 1.03-1.18 per unit increase) and higher serum hs-cardiac troponin I (HR = 4.09, 95% CI 1.36-12.2 per unit increase) were major contributors to moderate-to-severe QTc prolongation. In this closely screened and monitored cohort, no complications derived from QTc prolongation were observed during pharmacological therapy containing HCQ for COVID-19. Evidence of myocardial injury with elevated troponin and strong inflammatory response, specifically higher NLR, are conditions requiring careful QTc interval monitoring.

Cardiac workup and monitoring in hospitalised children with COVID- 19

Approximately, 1.7 million individuals in the United States have been infected with SARS-CoV-2, the virus responsible for the novel coronavirus disease-2019 (COVID-19). This has disproportionately impacted adults, but many children have been infected and hospitalised as well. To date, there is not much information published addressing the cardiac workup and monitoring of children with COVID-19. Here, we share the approach to the cardiac workup and monitoring utilised at a large congenital heart centre in New York City, the epicentre of the COVID-19 pandemic in the United States.

Acute effect of a peritoneal dialysis exchange on electrolyte concentration and QT interval in uraemic patients

BACKGROUND

Hemodialysis (HD) sessions induce changes in plasma electrolytes that lead to modifications of QT interval, virtually associated with dangerous arrhythmias. It is not known whether such a phenomenon occurs even during peritoneal dialysis (PD). The aim of the study is to analyze the relationship between dialysate and plasma electrolyte modifications and QT interval during a PD exchange.

METHODS

In 15 patients, two manual PD 4-h exchanges were performed, using two isotonic solutions with different calcium concentration (Ca⁺⁺1.25 and Ca1.75⁺⁺ mmol/L). Dialysate and plasma electrolyte concentration and QT interval (ECG Holter recording) were monitored hourly. A computational model simulating the ventricular action potential during the exchange was also performed.

RESULTS

Dialysis exchange induced a significant plasma alkalizing effect (p < 0.001). Plasma K⁺ significantly decreased at the third hour (p < 0.05). Plasma Na⁺ significantly decreased (p < 0.001), while plasma Ca⁺⁺ slightly increased only when using the Ca 1.75⁺⁺ mmol/L solution (p < 0.01). The PD exchange did not induce modifications of clinical relevance in the QT interval, while a significant decrease in heart rate (p < 0.001) was observed. The changes in plasma K⁺ values were significantly inversely correlated to QT interval modifications (p < 0.001), indicating that even small decreases of K⁺ were consistently paralleled by small QT prolongations. These results were perfectly confirmed by the computational model.

CONCLUSIONS

The PD exchange guarantees a greater cardiac electrical stability compared to the HD session and should be preferred in patients with a higher arrhythmic risk. Moreover, our study shows that ventricular repolarization is extremely sensitive to plasma K⁺ changes, also in normal range.