Pharmacological treatment of acquired QT prolongation and torsades de pointes

Taurine and enzymatically modified isoquercitrin protected against methotrexate-induced deteriorations in the conductivity and rhythmicity of the heart in rats: Antioxidant, anti-inflammatory, and histological architecture approach

Cardiotoxicity is one of the most devastating complications of cancer treatment by methotrexate (MTX). The present study aimed to investigate the potential anti-cardiotoxic efficacy of taurine (Tau) and enzymatically modified isoquercitrin (EMIQ) alone or combined against MTX-induced cardiotoxicity in adult male rats. A total of 36 rats were randomly divided into six groups (six animals each): control, MTX (a single i.p. dose of 20 mg/kg), EMIQ + MTX (26 mg/kg of EMIQ, p.o. for 16 days), Tau + MTX (500 mg/kg of Tau, p.o. for 16 days), EMIQ + Tau + MTX at the same previous doses, and (EMIQ + Tau)½ + MTX. MTX reduced the percentage of body weight change, the expression of dihydrofolate reductase (DHFR) and folypolyglutamyl synthetase (FPGS), the cleaved tumor necrosis factor alpha (TNF-α) level in the cardiac tissue, and the elevated serum TNF-α level. MTX extensively deteriorated the electrocardiography (ECG), inducing tachycardia with shortening of the time intervals between successive heartbeats (R-R interval), associated with elongation of ventricular depolarization (QRS interval), and the corrected total time for ventricular de- and repolarization (QTc) duration. Treatment with MTX resulted in a significant reduction in atrial depolarization (P amplitude) and rapid repolarization (T amplitude) and a significant elevation in plateau phase (ST height). MTX treatment resulted in swelling of cardiomyocytes with extensive vacuolization of sarcoplasm with numerous variably sized vacuoles in addition to apoptotic cells. Tau and EMIQ protected against MTX-induced deteriorations in the conductivity and rhythmicity of the heart through antioxidative, anti-inflammatory, and antiapoptotic activities. Treatment with tau and EMIQ combined at high or low doses offered superior protection to the heart than using each agent alone.

Impact of preoperative QTc interval prolongation on short-term postoperative outcomes: A retrospective study

STUDY OBJECTIVE

Although a prolonged heart rate-corrected QT interval (QTcI) is associated with an increased risk of mortality in the general population, its prognostic value in surgical patients remains unclear. We aimed to examine whether preoperative QTcI prolongation predicts short-term postoperative outcomes in elderly patients undergoing noncardiac surgery.

DESIGN

The study was a retrospective analysis using the TriNetX network database.

SETTING

Operating room.

INTERVENTION

Assessment and categorization of preoperative QTcI.

PATIENTS

Data of patients aged ≥65 years who underwent non-cardiac surgery between 2010 and 2023 were analyzed.

MEASUREMENTS

Patients were categorized into four groups based on preoperative QTcI: long (500-600 ms), borderline (460-500 ms), high-normal (420-460 ms) and control (370-420 ms) groups. The groups were compared using a propensity score-matched analysis. The primary outcome was the all-cause 90-day mortality risk. The secondary outcomes included 90-day risks of postoperative new-onset atrial fibrillation (Af), ventricular arrhythmias (VAs), emergency visits, hospital readmissions, and pneumonia.

RESULTS

In total, data on 519,929 patients were collected in this study. Pairwise comparisons showed that all QTcI prolongation groups demonstrated a heightened incidence of postoperative mortality, arrhythmias, and other complications compared to the control group. Patients with a long QTcI had a 3-fold higher risk of mortality (hazard ratio [HR] = 3.124, p < 0.001), Af (HR = 3.059, p < 0.001), and VAs (HR = 3.617, p < 0.001) than controls. The risks of emergency visits (HR = 1.287, p < 0.001), hospital readmissions (HR = 1.591, p < 0.001), and pneumonia (HR = 1.672, p < 0.001) were also higher in the long QTcI group than in the control group. A dose-dependent response was evident between QTcI and mortality as well as arrhythmia risk.

CONCLUSION

Preoperative QTcI screening effectively risk-stratifies elderly surgical patients, with a QTcI≥500 ms being strongly predictive of short-term postoperative mortality and other complications. Incorporating QTcI assessment into the preoperative evaluation may guide perioperative monitoring and management.

Mechanisms underlying the spontaneous termination of torsades de pointes in an experimental model of long QT syndrome

BACKGROUND

Torsades de pointes (TdP) represent a complex polymorphic ventricular tachycardia. While the triggering mechanisms of early afterdepolarization and increased dispersion of repolarization are well investigated, the sudden self-limiting termination remains poorly understood.

OBJECTIVE

The purpose of this study was to perform analysis of TdP to investigate factors causing spontaneous termination.

METHODS

We used a large data set from Langendorff experiments in isolated rabbit hearts in which drug-induced QT prolongation, bradycardia, and hypokalemia provoke TdP. We included 427 episodes with typical TdP characteristics of polymorphic self-terminating beats and twisting QRS complexes occurring in the presence of abnormal QT prolongation due to various different QT-prolonging drugs. The use of 8 monophasic action potential catheters allowed the characterization of action potential duration, configuration, and dispersion of repolarization beyond the capabilities of the surface electrocardiogram. To identify possible mechanisms of arrhythmia termination, the initial, midpoint, and terminal 3 ventricular complexes were analyzed for each episode.

RESULTS

An abrupt decrease in spatial dispersion over the course of a TdP episode was identified as a precursor for termination of TdP. Within the last 3 beats, a sudden significant decrease in the dispersion of repolarization was observed as a predictor of termination. In parallel, there was a decrease in action potential duration (action potential duration at 90% repolarization) before termination. Also, a change in action potential configuration (action potential duration at 90% repolarization/action potential duration at 50% repolarization ratio) in terms of the loss of action potential dome with a restitution of action potential triangulation was observed.

CONCLUSION

In >400 TdP episodes, homogenization of myocardial repolarization with the recovery of an action potential configuration determines the termination of TdP episodes.

Simultaneous electromechanical monitoring in engineered heart tissues using a mesoscale framework

Engineered heart tissues (EHTs) generated from human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent powerful platforms for human cardiac research, especially in drug testing and disease modeling. Here, we report a flexible, three-dimensional electronic framework that enables real-time, spatiotemporal analysis of electrophysiologic and mechanical signals in EHTs under physiological loading conditions for dynamic, noninvasive, longer-term assessments. These electromechanically monitored EHTs support multisite measurements throughout the tissue under baseline conditions and in response to stimuli. Demonstrations include uses in tracking physiological responses to pharmacologically active agents and in capturing electrophysiological characteristics of reentrant arrhythmias. This platform facilitates precise analysis of signal location and conduction velocity in human cardiomyocyte tissues, as the basis for a broad range of advanced cardiovascular studies.

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.

Long QT Syndrome With Drugs Used in the Management of Arrhythmias: A Systematic Review

Long QT syndrome (LQTS) is a severe cardiac disorder characterized by an abnormally prolonged QTc interval on an electrocardiogram (ECG), which can result in life-threatening irregular heart rhythms. The use of certain medications, particularly anti-arrhythmic drugs such as quinidine, sotalol, and amiodarone, can lead to acquired LQTS by prolonging the QT interval through the inhibition of specific ion channels responsible for heart repolarization, which may present symptoms like fainting, seizures, and sudden cardiac arrest. This systematic review, conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, focused on analyzing the association between Long QT syndrome and drugs utilized for managing arrhythmias, involving a thorough examination of six selected studies from an initial pool of 68 articles. It was found that antiarrhythmic drugs such as amiodarone, sotalol, dofetilide, procainamide, quinidine, and flecainide have the potential to cause QT prolongation as a side effect, which is often influenced by factors including dosage, coexisting medical conditions, electrolyte imbalances, and other risk factors. Prolonged QT interval significantly elevates the risk of a life-threatening arrhythmia called torsade de pointes. The management of this side effect typically involves reducing the medication dosage or discontinuing it altogether and, in some cases, employing selective beta blockers. However, further research is essential to improve the understanding and implementation of strategies to prevent and manage QT prolongation caused by antiarrhythmic drugs. Additional clinical studies are warranted to enhance knowledge and provide comprehensive guidelines to healthcare practitioners regarding the appropriate use of these medications. Close monitoring of the QT interval is recommended for patients receiving anti-arrhythmic therapy, and consideration should be given to patient-specific risk factors for LQTS, including age, sex, and electrolyte imbalances.

Tinospora cordifolia Extract Enhances Dextromethorphan Bioavailability: Implications for Alzheimer's Disease

Tinospora cordifolia (Willd.) Miers (Menispermaceae) is a traditional rejuvenator and a conventional medicine used to manage oxidative stress-related diseases, including those associated with the central nervous system. Decreased dextromethorphan (DEM) metabolism is necessary for high bioavailability and application against Alzheimer's disease (AD). Since T. cordifolia stem extract (TCE) can potentially inhibit several metabolic enzymes, it can also enhance dextromethorphan bioavailability. This study investigates the potential of TCE to improve DEM's bioavailability and efficacy for the management of AD. In silico analysis was carried out to find the inhibition potential of phytocomponents of T. cordifolia for CYP2D6 and CYP3A4. The LC-MS method was revalidated for the analysis of DEM and metabolite dextrorphan (DEX) in the presence of quinidine (QN). The ratio of DEM to DEX was estimated with varying doses of TCE following pharmacokinetic analysis. Network pharmacology analysis was carried out to understand the complementary potential of phytocomponents. This was further validated in the scopolamine-induced dementia model through behavioral and histopathological analyses. TCE (100 mg/kg) for 14 days increased the DEM to DEX ratio by 2.8-fold compared to QN treatment. While T max was comparable to that of QN treatment at this dose (100 mg/kg) of TCE, it increased significantly at the higher dose (400 mg/kg) of TCE pretreatment. All other pharmacokinetic parameters were also enhanced at this dose with a 4.7-fold increase in DEM/DEX compared with QN. Network pharmacology analysis indicated the ability of TCE to target multiple factors associated with AD. Furthermore, it improved spatial memory and reduced hyperactivity in rodents better than the combination of QN and DEM.

High-Degree Atrioventricular Block and Torsades De Pointes in Severe Aortic Stenosis Treated With Transcatheter Aortic Valve Replacement

Severe aortic stenosis (AS) significantly elevates cardiovascular risk, predisposing patients to high-degree atrioventricular (AV) block and life-threatening tachyarrhythmias, including torsades de pointes (TdP). This case report presents a patient with severe AS who developed high-degree AV block and, subsequently, TdP, highlighting the interplay between bradycardia and mechanisms that trigger ventricular tachycardias. The case underscores the importance of identifying and managing these risk factors to improve patient outcomes.

Retrosternal hematoma causing torsade de pointes after coronary artery bypass graft surgery; a case report

Myocardial infarction is among the top causes of mortality worldwide. Survivors may also experience several complications. Infarct-related torsade de pointes (TdP) is an uncommon complication. In the context of myocardial infarction, coronary artery bypass graft (CABG) surgery is the prevalent therapeutic modality associated with several early and late complications. Ventricular tachyarrhythmias, including TdP, because of electrical inhomogeneity, would potentially be a lethal complication of CABG. Here, we report the occurrence of medically intractable TdP in the presence of an uncommon case of a post-CABG retrosternal hematoma. Arrhythmia was properly resolved after hematoma removal surgically. It showed the possibility of a "cause and effect" relationship between these two complications. This unique case emphasizes the post-CABG medically-resistant TdP, considering the mechanical pressure effect of retrosternal hematoma that stimulates this potentially malignant arrhythmia, especially in the absence of electrolyte disturbances and evident symptoms of ongoing ischemia.

Dynamic "spiked helmet sign": Further evidence for prolonged QT

A 69-year-old woman was admitted after a cardiac arrest. She developed status epilepticus and was later found to have variable morphologies of a "spiked helmet sign" (SHS) on ECGs in the setting of prolonged QT interval, raising the question of whether this sign is a manifestation of QT prolongation.

Common pitfalls in the use of hypertonic sodium bicarbonate for cardiac toxic drug poisonings

BACKGROUND

Hypertonic sodium bicarbonate is advocated for the treatment of sodium channel blocker poisoning, but its efficacy varies amongst different sodium channel blockers. This Commentary addresses common pitfalls and appropriate usage of hypertonic sodium bicarbonate therapy in cardiotoxic drug poisonings.

SODIUM BICARBONATE WORKS SYNERGISTICALLY WITH HYPERVENTILATION

Serum alkalinization is best achieved by the synergistic effect of hypertonic sodium bicarbonate and hyperventilation (PCO2 ∼ 30-35 mmHg [0.47-0.6 kPa]). This reduces the dose of sodium bicarbonate required to achieve serum alkalinization (pH ∼ 7.45-7.55) and avoids adverse effects from excessive doses of hypertonic sodium bicarbonate.

VARIABILITY IN RESPONSE TO SODIUM BICARBONATE TREATMENT

Tricyclic antidepressant poisoning responds well to sodium bicarbonate therapy, but many other sodium channel blockers may not. For instance, drugs that block the intercellular gap junctions, such as bupropion, do not respond well to alkalinization. For sodium channel blocker poisonings in which the expected response is unknown, a bolus of 1-2 mmol/kg sodium bicarbonate can be used to assess the response to alkalinization.

SODIUM BICARBONATE CAN EXACERBATE TOXICITY FROM DRUGS ACTING ON MULTIPLE CARDIAC CHANNELS

Hypertonic sodium bicarbonate can cause electrolyte abnormalities such as hypokalaemia and hypocalcaemia, leading to QT interval prolongation and torsade de pointes in poisonings with drugs that have mixed sodium and potassium cardiac channel properties, such as hydroxychloroquine and flecainide.

THE GOAL FOR HYPERTONIC SODIUM BICARBONATE IS TO ACHIEVE THE ALKALINIZATION TARGET (∼PH 7.5), NOT COMPLETE CORRECTION OF QRS COMPLEX PROLONGATION

Excessive doses of hypertonic sodium bicarbonate commonly occur if it is administered until the QRS complex duration is < 100 ms. A prolonged QRS complex duration is not specific for sodium channel blocker toxicity. Some sodium channel blockers do not respond, and even when there is a response, it takes a few hours for the QRS complex duration to return completely to normal. In addition, QRS complex prolongation can be due to a rate-dependent bundle branch block. So, no further doses should be given after achieving serum alkalinization (pH ∼ 7.45-7.55).

MAXIMAL DOSING FOR HYPERTONIC SODIUM BICARBONATE

A further strategy to avoid overdosing patients with hypertonic sodium bicarbonate is to set maximum doses. Exceeding 6 mmol/kg is likely to cause hypernatremia, fluid overload, metabolic alkalosis, and cerebral oedema in many patients and potentially be lethal.

RECOMMENDATION FOR THE USE OF HYPERTONIC SODIUM BICARBONATE IN SODIUM CHANNEL BLOCKER POISONING

We propose that hypertonic sodium bicarbonate therapy be used in patients with sodium channel blocker poisoning who have clinically significant toxicities such as seizures, shock (systolic blood pressure < 90 mmHg, mean arterial pressure <65 mmHg) or ventricular dysrhythmia. We recommend initial bolus dosing of hypertonic sodium bicarbonate of 1-2 mmol/kg, which can be repeated if the patient remains unstable, up to a maximum dose of 6 mmol/kg. This is recommended to be administered in conjunction with mechanical ventilation and hyperventilation to achieve serum alkalinization (PCO2∼30-35 mmHg [4-4.7 kPa]) and a pH of ∼7.45-7.55. With repeated bolus doses of hypertonic sodium bicarbonate, it is imperative to monitor and correct potassium and sodium abnormalities and observe changes in serum pH and on the electrocardiogram.

CONCLUSIONS

Hypertonic sodium bicarbonate is an effective antidote for certain sodium channel blocker poisonings, such as tricyclic antidepressants, and when used in appropriate dosing, it works synergistically with hyperventilation to achieve serum alkalinization and to reduce sodium channel blockade. However, there are many pitfalls that can lead to excessive sodium bicarbonate therapy and severe adverse effects.

Overdrive Pacing for Persistent Torsades de Pointes and Pulseless Ventricular Tachycardia

A 53-year-old presented to the emergency department following a fall and was found to have recurrent episodes of torsades de pointes and pulseless ventricular tachycardia on cardiac monitoring. He had been abusing nimetazepam for sleep issues over the preceding one month. Despite correction of electrolytes, the arrhythmias were persistent which necessitated temporary overdrive pacing. The patient made an uneventful recovery and the temporary pacing was successfully removed with no recurrence of the malignant arrhythmias prior to discharge.

Exploring the Spectrum of VEGF Inhibitors' Toxicities from Systemic to Intra-Vitreal Usage in Medical Practice

The use of Vascular Endothelial Growth Factor inhibitors (VEGFi) has become prevalent in the field of medicine, given the high incidence of various pathological conditions necessitating VEGF inhibition within the general population. These conditions encompass a range of advanced neoplasms, such as colorectal cancer, non-small cell lung cancer, renal cancer, ovarian cancer, and others, along with ocular diseases. The utilization of VEGFi is not without potential risks and adverse effects, requiring healthcare providers to be well-prepared for identification and management. VEGFi can be broadly categorized into two groups: antibodies or chimeric proteins that specifically target VEGF (bevacizumab, ramucirumab, aflibercept, ranibizumab, and brolucizumab) and non-selective and selective small molecules (sunitinib, sorafenib, cabozantinib, lenvatinib, regorafenib, etc.) designed to impede intracellular signaling of the VEGF receptor (RTKi, receptor tyrosine kinase inhibitors). The presentation and mechanisms of adverse effects resulting from VEGFi depend primarily on this distinction and the route of drug administration (systemic or intra-vitreal). This review provides a thorough examination of the causes, recognition, management, and preventive strategies for VEGFi toxicities with the goal of offering support to oncologists in both clinical practice and the design of clinical trials.

Rat Model of Isoproterenol-Induced Myocardial Injury

Isoproterenol (ISO) administration produces significant biochemical and histological changes including oxidative stress, reactive oxygen species (ROS) overproduction, and inflammation that leads to aggravation of myocardial injury. Subcutaneous or intraperitoneal ISO injection into rats can replicate several features of human heart disease, making it a useful tool for comprehending the underlying mechanisms and evaluating potential therapeutic strategies. In the present chapter, we elaborate on how depending on the precise experimental goals and the intended level of severity, different dosages and regimens are employed to induce myocardial injury.

Effects of nicorandil on QT prolongation and myocardial damage caused by citalopram in rats

Citalopram is a selective serotonin re-uptake inhibitor (SSRI) antidepressant; it exhibits the greatest cardiotoxic effect among SSRIs. Citalopram can cause drug-induced long QT syndrome (LQTS) and ventricular arrhythmias. We investigated the protective effect of nicorandil, a selective mitochondrial KATP (mito-KATP) channel opener, on LQTS and myocardial damage caused by citalopram in male rats. In a preliminary study, we determined that the minimum citalopram dose that prolonged the QT interval was 102 mg/kg injected intraperitoneally. For the main study, rats were divided randomly into five experimental groups: untreated control, normal saline + citalopram, nicorandil + citalopram, 5-hydroxydecanoate (5-HD) + citalopram, 5-HD + nicorandil + citalopram. Biochemical and histologic data from blood and heart tissue samples from six untreated control rats were evaluated. Electrocardiographic parameters including QRS duration, QT interval, corrected QT interval (QTc) and heart rate (HR) were assessed, and biochemical parameters including malondialdehyde, reduced glutathione, glutathione peroxidase, superoxide dismutase were measured. We also performed histomorphologic and immunohistochemical examination of heart tissue. Citalopram prolonged QT-QTc intervals significantly and increased significantly the histomorphologic score and proportion of apoptotic cells, but produced no differences in the oxidant and antioxidant parameters. Nicorandil did not prevent citalopram induced QT-QTc interval prolongation and produced no significant changes in oxidant and antioxidant parameters; however, it did reduce histologic damage and apoptosis caused by citalopram.

Rapid changes of mRNA expressions of cardiac ion channels affected by Torsadogenic drugs influence susceptibility of rat hearts to arrhythmias induced by Beta-Adrenergic stimulation

Drug-induced long QT syndrome (LQTS) and Torsades de Pointes (TdP) are serious concerns in drug development. Although rats are a useful scientific tool, their hearts, unlike larger species, usually do not respond to torsadogenic drugs. Consequently, their resistance to drug-induced arrhythmias is poorly understood. Here, we challenged rats with rapid delayed rectifier current (Ikr)-inhibiting antibiotic clarithromycin (CLA), loop diuretic furosemide (FUR) or their combination (CLA + FUR), and examined functional and molecular abnormalities after stimulation with isoproterenol. Clarithromycin and furosemide were administered orally at 12-h intervals for 7 days. To evaluate electrical instability, electrocardiography (ECG) was recorded either in vivo or ex vivo using the Langendorff-perfused heart method under basal conditions and subsequently under beta-adrenergic stimulation. Gene expression was measured using real-time quantitative PCR in left ventricular tissue. Indeed, FUR and CLA + FUR rats exhibited hypokalemia. CLA and CLA + FUR treatment resulted in drug-induced LQTS and even an episode of TdP in one CLA + FUR rat. The combined treatment dysregulated gene expression of several ion channels subunits, including KCNQ1, calcium channels and Na+/K + -ATPase subunits, while both monotherapies had no impact. The rat with recorded TdP exhibited differences in the expression of ion channel genes compared to the rest of rats within the CLA + FUR group. The ECG changes were not detected in isolated perfused hearts. Hence, we report rapid orchestration of ion channel reprogramming of hearts with QT prolongation induced by simultaneous administration of clarithromycin and furosemide in rats, which may account for their ability to avoid arrhythmias triggered by beta-adrenergic stimulation.

Pathophysiology and treatment of adults with arrhythmias in the emergency department, part 2: Ventricular and bradyarrhythmias

PURPOSE

This is the second article in a 2-part series reviewing the pathophysiology and treatment considerations for arrhythmias. Part 1 of the series discussed aspects related to treating atrial arrhythmias. Here in part 2, the pathophysiology of ventricular arrhythmias and bradyarrhythmias and current evidence on treatment approaches are reviewed.

SUMMARY

Ventricular arrhythmias can arise suddenly and are a common cause of sudden cardiac death. Several antiarrhythmics may be effective in management of ventricular arrhythmias, but there is robust evidence to support the use of only a few of these agents, and such evidence was largely derived from trials involving patients with out-of-hospital cardiac arrest. Bradyarrhythmias range from asymptomatic mild prolongation of nodal conduction to severe conduction delays and impending cardiac arrest. Vasopressors, chronotropes, and pacing strategies require careful attention and titration to minimize adverse effects and patient harm.

CONCLUSION

Ventricular arrhythmias and bradyarrhythmias can be consequential and require acute intervention. As experts in pharmacotherapy, acute care pharmacists can participate in providing high-level intervention by aiding in diagnostic workup and medication selection.

Quelling the Storm: A Review of the Management of Electrical Storm

Heightened sympathetic input to the myocardium potentiates cardiac electrical instability and may herald an electrical storm. An electrical storm is characterized by 3 or more episodes of ventricular tachycardia, ventricular fibrillation, or appropriate internal cardiac defibrillator shocks within 24 hours. Management of electrical storms is resource-intensive and inevitably requires careful coordination between multiple subspecialties. Anesthesiologists have an important role in acute, subacute, and long-term management. Identifying the phase of an electrical storm and understanding the characteristics of each morphology may help the anesthesiologist anticipate the management approach. In the acute phase, management of an electrical storm is aimed at providing advanced cardiac life support and identifying reversible causes. After initial stabilization, subacute management focuses on dampening the sympathetic surge with sedation, thoracic epidural, or stellate ganglion blockade. Definitive long-term management with surgical sympathectomy or catheter ablation also may be warranted. Our objective is to provide an overview of electrical storms and the anesthesiologist's role in management.

Unraveling Structural Alerts in Marketed Drugs for Improving Adverse Outcome Pathway Framework of Drug-Induced QT Prolongation

In pharmaceutical treatment, many non-cardiac drugs carry the risk of prolonging the QT interval, which can lead to fatal cardiac complications such as torsades de points (TdP). Although the unexpected blockade of ion channels has been widely considered to be one of the main reasons for affecting the repolarization phase of the cardiac action potential and leading to QT interval prolongation, the lack of knowledge regarding chemical structures in drugs that may induce the prolongation of the QT interval remains a barrier to further understanding the underlying mechanism and developing an effective prediction strategy. In this study, we thoroughly investigated the differences in chemical structures between QT-prolonging drugs and drugs with no drug-induced QT prolongation (DIQT) concerns, based on the Drug-Induced QT Prolongation Atlas (DIQTA) dataset. Three categories of structural alerts (SAs), namely amines, ethers, and aromatic compounds, appeared in large quantities in QT-prolonging drugs, but rarely in drugs with no DIQT concerns, indicating a close association between SAs and the risk of DIQT. Moreover, using the molecular descriptors associated with these three categories of SAs as features, the structure–activity relationship (SAR) model for predicting the high risk of inducing QT interval prolongation of marketed drugs achieved recall rates of 72.5% and 80.0% for the DIQTA dataset and the FDA Adverse Event Reporting System (FAERS) dataset, respectively. Our findings may promote a better understanding of the mechanism of DIQT and facilitate research on cardiac adverse drug reactions in drug development.

C-L Case Conference: Torsades de Pointes in a Patient With Lifelong Medical Trauma, COVID-19, Remdesivir, Citalopram, Quetiapine, and Hemodialysis

We present a case of Torsades de Pointes (TdP) in a patient with COVID-19 infection and multiple TdP risk factors including QT-interval prolongation, hemodialysis, bradycardia, and treatment with remdesivir, citalopram, and quetiapine. The case was complicated by post-resuscitation anxiety superimposed on a history of medical trauma since childhood. Top experts in the field of consultation-liaison psychiatry, trauma informed care, and cardiac electrophysiology provide perspectives on this case with a review of the literature. Key teaching topics include identification of TdP risk factors in patients with a complex illness; the necessity for prompt electrophysiology consultation in clinical scenarios with high risk for TdP; and the approach to patients with medical trauma using a trauma-informed lens. We highlight the contributions of COVID-19, the pharmacokinetics of QT-interval-prolonging psychotropic medications, the risks of hemodialysis, and the role of remdesivir-induced bradycardia in this first reported case of TdP in a patient treated with remdesivir.

Treatment of Arrhythmias During Pregnancy

Cardiac disease is the most common cause of maternal mortality in developed nations. Cardiac arrhythmias are frequent among patients with structural heart disease and may require immediate treatment to prevent hemodynamic instability leading to acute maternal and fetal decompensation. Antiarrhythmic therapy during pregnancy should follow the same principles recommended for nonpregnant individuals. Although multidisciplinary management is recommended, obstetricians, and maternal-fetal medicine specialists may sometimes need to emergently recognize and treat rhythm anomalies before support services become available.

Antipsychotics and risk of QT prolongation: a pharmacovigilance study

RATIONALE

While meta-analyses of clinical trials found that lurasidone and partial dopamine agonists (brexpiprazole and aripiprazole) were the antipsychotics less likely to cause QTc prolongation, and sertindole, amisulpride, and ziprasidone were the most frequently associated with this adverse drug reaction; no real-world studies have investigated this risk between the different antipsychotics.

OBJECTIVES AND METHODS

Using data recorded from 1967 to 2019 in VigiBase®, the World Health Organization's Global Individual Case Safety Reports database, we performed disproportionality analysis to investigate the risk of reporting QT prolongation between 20 antipsychotics.

RESULTS

Sertindole had the highest risk of reporting QT prolongation, followed by ziprasidone and amisulpride. Lurasidone was associated with the lowest risk. First-generation antipsychotics were associated with a greater QT prolongation reporting risk (ROR, 1.21; 95%CI, 1.10-1.33) than second-generation antipsychotics. A positive correlation was found between the risk of reporting QT prolongation and affinity for hERG channel (R² = 0.14, slope = Pearson coefficient = 0.41, p value = 0.1945).

CONCLUSIONS

This large study in a real-world setting suggests that sertindole and ziprasidone were the antipsychotics drugs associated with the highest risk of QT prolongation reporting. Our results suggest that lurasidone is less associated with QT interval prolongation reports. Our study also suggests that antipsychotics with the higher hERG affinity are more associated with to QT prolongations reports.

Intraoperative Analgesia with Magnesium Sulfate versus Remifentanil Guided by Plethysmographic Stress Index in Post-Bariatric Dermolipectomy: A Randomized Study

BACKGROUND

Magnesium sulfate reduces pain scores and analgesic consumption. Its use as an analgesic resource in opioid-free or opioid-sparing techniques have also been tested. The evaluation of the antinociceptive potency of drugs and doses indirectly, through hemodynamic oscillations has been questioned. A relatively new algorithm called the plethysmographic stress index has been considered sensitive and relatively specific as a parameter for assessing the need for intraoperative analgesia.

OBJECTIVES

The aim of this trial was to assess the intraoperative analgesic capacity of magnesium sulfate compared to remifentanil. The secondary objectives were propofol consumption and its latency, the consumption of opioids, ephedrine, and cisatracurium. Patients and Methods. Forty patients scheduled for post-bariatric dermolipectomy were randomly assigned to two groups to receive total intravenous anesthesia with target-controlled hypnosis induced with propofol. Analgesia was obtained in the remifentanil group with remifentanil at an initial dose of 0.2 μg·kg-1·min-1 and in the magnesium sulfate group with magnesium sulfate 40 mg·kg-1 + 10 mg·kg-1·h-1.

RESULTS

There was no statistical hemodynamic difference between the groups before and after orotracheal intubation (p = 0.062) and before and after the surgical incision (p = 0.656). There was also no statistical difference in the variation of mean arterial pressure before and after intubation (p = 0.656) and before and after the surgical incision (p = 0.911). There was similar consumption of cisatracurium, ephedrine, and postoperative opioids between the groups. Some patients in the magnesium sulfate group needed more intraoperative fentanyl and propofol, although the latency of propofol was similar in both the groups.

CONCLUSION

We conclude that using magnesium sulfate in intravenous general anesthesia for post-bariatric dermolipectomy is related to a significant reduction in opioid consumption without compromising hemodynamic stability. Overall, PSI monitoring was helpful in driving the analgesic strategy. The use of magnesium sulfate proved to be an important adjunct in the scenario presented, allowing the use of opioids to be avoided in certain cases. We found no statistical differences in the consumption of neuromuscular blocker and vasoconstrictor. Substituting opioids for magnesium sulfate leads to an increase in propofol consumption in the scenario presented. Studies with a larger sample are needed to corroborate the results presented and evaluate other potential advantages in reducing opioid consumption.

Overdrive pacing in the acute management of osimertinib-induced ventricular arrhythmias: A case report and literature review

QT interval prolongation and ventricular arrhythmias (VAs) induced by osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, are life-threatening complications. However, no consensus has been achieved regarding their management. Overdrive pacing has been shown to be effective in shortening the QT interval and terminating torsade de pointes (TdP). Here, we report a case of osimertinib-induced QT prolongation accompanied by frequent VAs and TdP. Osimertinib was immediately discontinued after it was identified as the etiology for QT prolongation and VAs. A temporary pacemaker and overdrive pacing were used after other anti-arrhythmia treatments had failed and successfully shortened the QTc interval and terminated VAs. Repeated Holter monitoring at 1 week showed no remaining VAs or TdP, and the pacemaker was removed. Routine electrocardiography (ECG) surveillance was conducted afterward, and three- and 6-month follow-ups showed good recovery and normal ECG results. Vigilance is required for rare vital arrhythmias in patients taking osimertinib, and ECG surveillance should be conducted.

Early Alterations of QTc in Patients with COVID-19 Treated with Hydroxychloroquine or Chloroquine in Libreville, Gabon

The objective of this study was to analyze the effect of hydroxychloroquine or chloroquine associated with azithromycin on the QTc interval in Gabonese patients treated for COVID-19.

METHODS

This was an observational study conducted from April to June 2020, at the Libreville University Hospital Center in Gabon. Patients admitted for COVID-19 and treated with hydroxychloroquine or chloroquine, each combined with azithromycin were included. The QTc interval was measured upon admission and 48 h after starting treatment. The primary endpoint was QTc prolongation exceeding 60 ms and/or a QTc value exceeding 500 ms at 48 h.

RESULTS

Data from 224 patients, 102 (45.5%) who received hydroxychloroquine and 122 treated with chloroquine, were analyzed. The median baseline QTc was 396 (369-419) ms. After 48 h of treatment, 50 (22.3%) patients had a significant prolongation of QTc. This tended to be more frequent in patients treated with chloroquine (n = 33; 27.0%) than in those treated with hydroxychloroquine (n = 17; 16.7%) (p = 0.06). QTc prolongation exceeding 60 ms was found in 48 (21.3%) patients, while 11 patients had a (4.9%) QTc exceeding 60 ms at admission and exceeding 500 ms after 48 h.

CONCLUSION

Early QTc prolongation is frequent in COVID-19 patients treated with hydroxychloroquine or chloroquine in association with azithromycin.

Utility of magnesium sulfate in the treatment of rapid atrial fibrillation in the emergency department: a systematic review and meta-analysis

Atrial fibrillation with rapid ventricular response (Afib/RVR) is a frequent reason for emergency department (ED) visits and can be treated with a variety of pharmacological agents. Magnesium sulfate has been used to prevent and treat postoperative Afib/RVR. We performed a systematic review and meta-analysis to assess the effectiveness of magnesium for treatment of Afib/RVR in the ED. PubMed and Scopus databases were searched up to June 2021 to identify any relevant randomized trials or observational studies. We used Cochrane's Risk-of-Bias tools to assess study qualities and random-effects meta-analysis for the difference of heart rate (HR) before and after treatment. Our search identified 395 studies; after reviewing 11 full texts, we included five randomized trials in our analysis. There were 815 patients with Afib/RVR; 487 patients (60%) received magnesium treatment, whereas 328 (40%) patients received control treatment. Magnesium treatment was associated with significant reduction in HR [standardized mean difference (SMD), 0.34; 95% CI, 0.21-0.47; P < 0.001; I2 = 4%), but not associated with higher rates of sinus conversion (OR, 1.46; 95% CI, 0.726-2.94; P = 0.29), nor higher rates of hypotension and bradycardia (OR, 2.2; 95% CI, 0.62-8.09; P = 0.22). Meta-regressions demonstrated that higher maintenance dose (corr. coeff, 0.17; P = 0.01) was positively correlated with HR reductions, respectively. We observed that magnesium infusion can be an effective rate control treatment for patients who presented to the ED with Afib/RVR. Further studies with more standardized forms of control and magnesium dosages are necessary to assess the benefit/risk ratio of magnesium treatment, besides to confirm our observations.

Drug Interactions Affecting Antiarrhythmic Drug Use

Antiarrhythmic drugs (AAD) play an important role in the management of arrhythmias. Drug interactions involving AAD are common in clinical practice. As AADs have a narrow therapeutic window, both pharmacokinetic as well as pharmacodynamic interactions involving AAD can result in serious adverse drug reactions ranging from arrhythmia recurrence, failure of device-based therapy, and heart failure, to death. Pharmacokinetic drug interactions frequently involve the inhibition of key metabolic pathways, resulting in accumulation of a substrate drug. Additionally, over the past 2 decades, the P-gp (permeability glycoprotein) has been increasingly cited as a significant source of drug interactions. Pharmacodynamic drug interactions involving AADs commonly involve additive QT prolongation. Amiodarone, quinidine, and dofetilide are AADs with numerous and clinically significant drug interactions. Recent studies have also demonstrated increased morbidity and mortality with the use of digoxin and other AAD which interact with P-gp. QT prolongation is an important pharmacodynamic interaction involving mainly Vaughan-Williams class III AAD as many commonly used drug classes, such as macrolide antibiotics, fluoroquinolone antibiotics, antipsychotics, and antiemetics prolong the QT interval. Whenever possible, serious drug-drug interactions involving AAD should be avoided. If unavoidable, patients will require closer monitoring and the concomitant use of interacting agents should be minimized. Increasing awareness of drug interactions among clinicians will significantly improve patient safety for patients with arrhythmias.

Risk assessment tools for QT prolonging pharmacotherapy in older adults: a systematic review

Purpose

Many drugs are associated with the risk of QT prolongation and torsades de pointes (TdP), and different risk assessment tools (RATs) are developed to help clinicians to manage related risk. The aim of this systematic review was to summarize the evidence of different RATs for QT prolonging pharmacotherapy.

Methods

A systematic review was conducted using PubMed and Scopus databases. Studies concerning risk assessment tools for QT prolonging pharmacotherapy, including older adults, were included. Screening and selection of the studies, data extraction, and risk of bias assessment were undertaken.

Results

A total of 21 studies were included, involving different risk assessment tools. Most commonly used tools were risk scores (n = 9), computerized physician order entry systems (n = 3), and clinical decision support systems (n = 6). The tools were developed mainly for physicians and pharmacists. Risk scores included a high number of risk factors, both pharmacological and non-pharmacological, for QT prolongation and TdP. The inclusion of patients’ risk factors in computerized physician order entry and clinical decision support systems varied.

Conclusion

Most of the risk assessment tools for QT prolonging pharmacotherapy give a comprehensive overview of patient-specific risks of QT prolongation and TdP and reduce modifiable risk factors and actual events. The risk assessment tools could be better adapted to different health information systems to help in clinical decision-making. Further studies on clinical validation of risk assessment tools with randomized controlled trials are needed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-022-03285-3.

Salbutamol-Induced QT Interval Prolongation in a Two-Year-Old Patient

Salbutamol-induced QT interval prolongation is a relatively rare adverse effect of beta2-agonists. We report a case of a two-year-old female patient with no known past medical history, brought by her parents to the ED 30 minutes after ingesting a total dose of 97 mg of salbutamol solution. ECG was done for the patient when she arrived and showed sinus tachycardia with prolonged QTc (509 ms) and normal QRS complex. The patient was admitted to the Pediatric Intensive Care Unit (PICU) with persistent tachycardia and tachypnea in the initial reassessment. ECG was repeated with normal QT interval after IV Mg sulfate. The patient was observed in PICU for 12 hours with serial ECG and venous blood gas (VBG). IV potassium chloride (KCL) infusion started, and serial VBG showed normal potassium and lactate. The patient was doing well in the next six hours, with normal serial ECG, labs, and vital signs.

In conclusion, salbutamol-induced QT prolongation has infrequently been reported in the literature. Although inhaled salbutamol is commonly used in clinical practice, physicians have limited experience with the severe features of its toxicity. Salbutamol is known to cause minimal side effects, which may be under-recognized and progress to serious manifestations such as hypokalemia, QT prolongation, and sudden cardiac death.

Treatment of adult, child and newborn cardiac arrest victims with COVID-19. Recommendations from the Interamerican Society of Cardiology / Sociedad Interamericana de Cardiología (SIAC), Mexican National Cardiologists Association / Asociación Nacional de Cardiólogos de México (ANCAM) and Mexican Society of Cardiology / Sociedad Mexicana de Cardiología (SMC)

La pandemia de COVID-19 ha infligido grandes estragos a la población y en especial al personal de salud. Los esfuerzos de reanimación exigen modificaciones potenciales de las guías internacionales existentes de reanimación cardiopulmonar (RCP) debido al elevado índice de contagiosidad del virus SARS-CoV-2. Se considera que hasta 15% de los casos de COVID-19 tiene una enfermedad grave y 5% padece un trastorno crítico con una mortalidad promedio del 3%, la cual varía según sean el país y las características de los pacientes. La edad y las comorbilidades como la hipertensión arterial, enfermedad cardiovascular, obesidad y diabetes incrementan la mortalidad hasta 24%. También se ha informado un aumento reciente del número de casos de paro cardíaco extrahospitalario (PCEH). Aunque el paro cardíaco (PC) puede ser efecto de factores diversos en estos pacientes, en la mayoría de los casos se ha demostrado que el origen es respiratorio, con muy pocos casos de causa cardíaca. Se debe considerar la indicación de iniciar o continuar las maniobras de RCP por dos razones fundamentales: la posibilidad de sobrevida de las víctimas, que hasta la fecha se ha registrado muy baja, y el riesgo de contagiar al personal de salud, que es muy alto.

The COVID-19 pandemic is having a large impact on the general population, but it has taken a specially high toll on healthcare personnel. Resuscitation efforts require potential modifications of the present Cardiopulmonary Resuscitation (CPR) international guidelines because of the transmissibility rate of the new SARS-CoV 2 virus. It has been seen that up to 15% of COVID-19 patients have a severe disease, 5% have a critical form of infection and the mean death rate is 3%, although there are significant differences according to the country that reports it and patients’ baseline conditions that include age, presence of arterial hypertension, cardiovascular disease, diabetes or obesity. In these high risk subjects, mortality might go up to 24%. There are also reports of a recent increase in out-of-hospital cardiopulmonary arrest (OHCA) victims. Cardiac arrest (CA) in these subjects might be related to many causes, but apparently, that phenomenon is related to respiratory diseases rather than cardiac issues. In this context, the decision to start or continue CPR maneuvers has to be carefully assessed, because of the low survival rate reported so far and the high contagion risk among healthcare personnel.

Vomiting, electrolyte disturbance, and medications; the perfect storm for acquired long QT syndrome and cardiac arrest: a case report

Background

Acquired long QT syndrome is an important and preventable cause of cardiac arrest. Certain medications and electrolyte disturbance are common contributors, and often coexist. In this case, we report five contributors to cardiac arrest.

Case presentation

This case is of a 51-year-old Caucasian female patient who presented with vomiting associated with hypokalemia and hypomagnesemia. She subsequently received ondansetron and metoclopramide, on the background of chronic treatment with fluoxetine. She then suffered an in-hospital monitored cardiac arrest, with features of long QT and torsades de pointes retrospectively noted on her prearrest electrocardiogram. She was diagnosed with acquired long QT syndrome, and her QT interval later normalized after removal of offending causes.

Conclusions

This case highlights the importance of proper consideration prior to prescribing QT prolonging medications, especially in patients who have other risk factors for prolonged QT, such as electrolyte disturbances and pretreatment with QT prolonging medications.

Refractory Torsades de Pointes Due to Dofetilide Overdose

Dofetilide, a class III antiarrhythmic, is widely used in the treatment of cardiac arrhythmias. Antiarrhythmic drugs can have a long duration of action that prolongs the QT interval. This causes bradycardia that predisposes to R-on-T phenomenon subsequently leading to torsades de pointes (TdP). This necessitates constant monitoring to prevent or treat ventricular arrhythmias or bradycardia associated with cardiac medications. Although extremely rare, dofetilide overdose has been described in the literature. However, no evidence found in the current literature required prolonged intervention after the initial acute stabilization, leading to scarcity of data for treatment of ongoing dofetilide overdose. We present the case of an intentional dofetilide overdose in a 61-year-old Caucasian woman with a history of congestive heart failure, atrial fibrillation, stage IIIb chronic kidney disease, diabetes mellitus type II, hypothyroidism, morbid obesity, and hypertension that required extensive interventions for refractory TdP that lasted 4 days. Therapeutic as well as excess dosage of dofetilide can lead to TdP, which is usually controlled by decreasing the dose or terminating drug administration. If the arrhythmia is not resolved, guidelines recommend management with activated charcoal if ingestion is within 15 minutes, followed by administration of 2 g IV (intravenous) magnesium and addressing the electrolyte imbalance. However, if the arrhythmia is persistent due to ongoing dofetilide toxicity, isoproterenol is given as a bridge to overdrive pacing and dopamine is used as an alternative to isoproterenol.

Torsades de pointes in the PACU after outpatient endoscopy: a case report

Background

This case demonstrates the severe electrolyte derangements that may present after a common therapy such as a bowel preparation for an outpatient procedure and the rare yet potential detrimental outcomes of those abnormalities. It also highlights the implications of long QT syndrome regarding pharmacology and treatment.

Case presentation

We present a case of 48 year-old female with severe electrolyte derangements and long QT syndrome (LQTS) leading to Torsades de Pointes (TdP), pulseless ventricular fibrillation, and unsynchronized defibrillation in the post anesthesia care unit (PACU) after uneventful upper and lower endoscopy. This led to an unanticipated intensive care unit admission for aggressive electrolyte repletion, cardiology consultation, and implantable cardioverter defibrillator (ICD) placement.

Conclusions

This is a rare presentation after an outpatient procedure that would have had a detrimental outcome if not promptly diagnosed and treated appropriately. Therefore, we aim to provide further insight into the diagnosis and treatment of severe hypokalemia and long QT syndrome resulting in Torsades de Pointes and ventricular fibrillation.

Clinical Pharmacology of the Dietary Supplement, Kratom (Mitragyna speciosa)

Kratom (Mitragyna speciosa) consists of over 40 alkaloids with two of them, mitragynine (MG) and 7-OH-mitragynine (7-OH-MG) being the main psychoactive compounds. MG and 7-OH-MG each target opioid receptors and have been referred to as atypical opioids. They exert their pharmacologic effects on the μ, δ, and κ opioid receptors. In addition, they affect adrenergic, serotonergic, and dopaminergic pathways. Kratom has been touted as an inexpensive, legal alternative to standard opioid replacement therapy such as methadone and buprenorphine. Other uses for kratom include chronic pain, attaining a "legal high," and numerous CNS disorders including anxiety depression and post-traumatic stress disorder (PTSD). Kratom induces analgesia and mild euphoria with a lower risk of respiratory depression or adverse central nervous system effects compared to traditional opioid medications. Nonetheless, kratom has been associated with both physical and psychological dependence with some individuals experiencing classic opioid withdrawal symptoms upon abrupt cessation. Kratom use has been linked to serious adverse effects including liver toxicity, seizures, and death. These risks are often compounded by poly-substance abuse. Further, kratom may potentiate the toxicity of coadministered medications through modulation of cytochrome P450, P-glycoprotein, and uridine diphosphate glucuronosyltransferase enzymes (UGDT). In 2016 the U.S. Drug Enforcement Administration (DEA) took steps to classify kratom as a federal schedule 1 medication; however, due to public resistance, this plan was set aside. Until studies are conducted that define kratom's role in treating opioid withdrawal and/or other CNS conditions, kratom will likely remain available as a dietary supplement for the foreseeable future. This article is protected by copyright. All rights reserved.

A Case of Sudden Cardiac Arrest

Editor's note: This is the next installment in a series on electrocardiogram (ECG) interpretation. Nurses in all settings should know the basics, as medications and physiological changes can cause cardiac arrhythmias. Each article will start with a brief case scenario and an ECG strip and then take you step by step through analyzing the heart rhythm.

Drug-Induced QTc Prolongation: What We Know and Where We Are Going

Drug-induced QTc prolongation is a concerning electrocardiogram (ECG) abnormality. This cardiac disturbance carries a 10% risk of sudden cardiac death due to the malignant arrhythmia, Torsades de Pointes. The Arizona Center for Education and Research on Therapeutics (AzCERT) has classified QTc prolonging therapeutic classes such as antiarrhythmics, antipsychotics, anti-infectives, and others. AzCERT criteria categorizes medications into three risk categories: "known," "possible," and "conditional risk" of QTc prolongation and Torsades de Pointes. The list of QTc prolonging medications continues to expand as new drug classes are approved and studied. Risk factors for QTc prolongation can be delineated into modifiable or non-modifiable. A validated risk scoring tool may be utilized to predict the likelihood of prolongation in patients receiving AzCERT classified medication. The resultant risk score may be applied to a clinical decision support system which offers mitigation strategies. Mitigation strategies including discontinuation of possible offending agents with selection of an alternative agent, assessment of potential drug interactions or dose adjustments through pharmacokinetic and pharmacodynamic monitoring, and initiation of both ECG and electrolyte monitoring are essential to prevent a drug-induced arrhythmia. The challenges presented by the COVID-19 pandemic have led to the development of innovative continuous monitoring technology, increasing protection for both patients and healthcare workers. Early intervention strategies may reduce adverse events and improve clinical outcomes in patients identified to be at risk of QTc prolongation.

Magnesium Treatment in Pediatric Patients

Pediatric patients may require magnesium replacement to treat life-threatening emergencies such as torsades de pointe or asthma exacerbations, as well as for the general replacement of magnesium in patients with hypomagnesemia. Clinicians must be aware of recommendations for magnesium administration as the route, dose, timing of administration, and formulation of magnesium can differ for each indication. It is imperative for clinicians to ensure that magnesium is appropriately administered to effectively treat the presenting indication and avoid adverse effects.

Torsades de Pointes due to Excessive Marijuana Use in a Susceptible Patient

There are several recent reports of tetrahydrocannabinol vaping-related sudden cardiac arrest, and the mechanisms are unclear. We report a unique case of a 19-year-old female who suffered documented prolonged QTc leading to Torsades de pointes and cardiac arrest in the setting of frequent marijuana wax vaping. While she demonstrated normal baseline QTc measurements years earlier, she was found to have a genetic predisposition to QTc prolongation (genetic mutation, family history of prolonged QTc), suggesting that specific patient populations are at higher risk of these adverse events. The patient was acutely managed with isoproterenol to increase the heart rate and was discharged on nadolol after placement of an implantable cardioverter-defibrillator. Marijuana wax vaping and dabbing may cause fatal Torsades de pointes in susceptible patients, and further research is required to identify these patients a priori.

The Use of Intravenous Lidocaine in the Setting of Chronic Dofetilide Overdose: A Case Report

Managing the risks and consequences of long QT syndrome can be challenging. Multiple factors contribute to the prolongation of the heart-rate corrected QT (QTc) interval including many drug-drug and drug-disease state interactions. Current literature is often focused on avoiding dysrhythmias with limited guidance on acute management strategies. Here we describe a case of QTc prolongation to 616 msec (Bazett's formula) in the setting of chronic dofetilide overdose due to a possible prescription error. Our case was complicated by alcohol withdrawal and electrolyte disturbances that progressed to patient cardiac arrest in the emergency department. Dofetilide overdose was identified through pharmacist-initiated medication reconciliation and lidocaine was recommended as an alternative to amiodarone during advanced cardiac life support (ACLS). This case highlights the importance of reviewing outpatient medication records as well as avoiding drug-drug interactions during ACLS. Due to the potential for additive QTc prolongation, we recommend using lidocaine as the preferred antiarrhythmic in ACLS algorithms where drug induced QTc prolongation is suspected.

Effect of ciprofloxacin vs levofloxacin on QTc-interval and dysglycemia in diabetic and non-diabetic patients

BACKGROUND

Levofloxacin and ciprofloxacin are more commonly used amongst fluoroquinolone class and the question of cardiac safety and glucose hemostasis of this class has been raised.

OBJECTIVE

To compare intravenous levofloxacin and ciprofloxacin regarding their risk on QTc prolongation and dysglycemia in diabetic and non-diabetic patients.

METHODS

A randomised prospective study at Beni-Suef university hospital was conducted on 200 adult patients over 6 months. The patients received intravenous levofloxacin 750mg once daily or ciprofloxacin 400mg twice daily. Electrocardiogram and fasting blood glucose were obtained from each patient before starting the antibiotic, 24 hours, 72 hours after the first dose, and 72 hours after antibiotics cessation.

RESULTS

The results of the current study showed the relative risk for QTc prolongation with levofloxacin was more than ciprofloxacin by about 4 and 1.5 times in diabetic and non-diabetic patients, respectively. The relative risk for dysglycemia with levofloxacin was 2.28 and 1.39 times more than ciprofloxacin in diabetic and non-diabetic patients, respectively.

CONCLUSION

The present study showed that the risk for QTc prolongation and hyperglycemia was greater with levofloxacin than ciprofloxacin in diabetic and non-diabetic patients. In addition, the risk for hypoglycemia was greater with levofloxacin than ciprofloxacin in non-diabetic patients.

Naturally occurring torsades de pointes and QT interval prolongation in a domestic cat

A 10-year-old male American Shorthair cat was presented after a witnessed syncopal event. A Holter monitor demonstrated a long QT interval and revealed a rhythm characteristic of torsades de pointes (TdP) coincident with a bout of syncope. On subsequent Holter monitor recordings, sotalol did not prolong the QT interval further and did not reduce the severity of the underlying ventricular tachyarrhythmias, but no TdP was identified. When another syncopal event occurred, sotalol was discontinued, and oral amiodarone and magnesium were started. This resulted in improvement in the ventricular tachyarrhythmia. No syncopal events occurred in the ensuing 3 months, but the cat died of an unrelated disease shortly after. This is the first report of naturally occurring torsades de pointes in a domestic cat.

Interrelated In Vitro Mechanisms of Sibutramine-Induced Cardiotoxicity

Consumption of illicit pharmaceutical products containing sibutramine has been reported to cause cardiovascular toxicity problems. This study aimed to demonstrate the toxicity profile of sibutramine, and thereby provide important implications for the development of more effective strategies in both clinical approaches and drug design studies. Action potentials (APs) were determined from freshly isolated ventricular cardiomyocytes with whole-cell configuration of current clamp as online. The maximum amplitude of APs (MAPs), the resting membrane potential (RMP), and AP duration from the repolarization phases were calculated from original records. The voltage-dependent K+-channel currents (IK) were recorded in the presence of external Cd2+ and both inward and outward parts of the current were calculated, while their expression levels were determined with qPCR. The levels of intracellular free Ca2+ and H+ (pHi) as well as reactive oxygen species (ROS) were measured using either a ratiometric micro-spectrofluorometer or confocal microscope. The mechanical activity of isolated hearts was observed with Langendorff-perfusion system. Acute sibutramine applications (10-8-10-5 M) induced significant alterations in both MAPs and RMP as well as the repolarization phases of APs and IK in a concentration-dependent manner. Sibutramine (10 μM) induced Ca2+-release from the sarcoplasmic reticulum under either electrical or caffeine stimulation, whereas it depressed left ventricular developed pressure with a marked decrease in the end-diastolic pressure. pHi inhibition by sibutramine supports the observed negative alterations in contractility. Changes in mRNA levels of different IK subunits are consistent with the acute inhibition of the repolarizing IK, affecting AP parameters, and provoke the cardiotoxicity.

Machine read frontal QRS-T angle and QTc is no substitute for manual measurement of QTc in pro-arrhythmic drug overdose

INTRODUCTION

To investigate whether there is an association between the blocking of cardiac potassium channels, which is characterised by a prolonged QTc interval and the frontal QRS-T angle after overdose by QT prolonging drugs.

METHODS

We obtained patient medical records associated with QT prolonging drugs from 3 different hospitals: the Calvary Mater Newcastle Hospital (CMNH), Royal Prince Alfred Hospital (RPAH) and Prince of Wales Hospital (POWH). RPAH and POWH admissions were taken between 4/01/2017 to 1/11/2019, and CMNH admissions were taken between 4/01/2013 to 24/06/2018. Demographic information and details of overdose were collected. All admission ECGs were manually measured. Linear regression was used to assess the relationship between various QTc formulas and the frontal QRS-T angle. A Bland-Altman plot was used to examine agreement between manual and machine QT intervals.

RESULTS

144 patients met the inclusion criteria for analysis. None of the patients developed torsades de pointes (TdP). There was no linear association between the QRS-T angle and the various QTc formulas (For QRS-T angle: QTcRTH: p = 0.76, QTcB: p = 0.83, QTcFri: p = 0.90, QTcFra: p = 0.13, QTcH: p = 0.97; For square root transformation of the QRS-T angle: QTcRTH: p = 0.18, QTcB: p = 0.33, QTcFri: p = 0.95, QTcFra: p = 0.47, QTcH: p = 0.33). Agreement between machine and manual QT measurements was low.

CONCLUSIONS

The frontal QRS-T angle cannot substitute the QTc in assessing the blockage of cardiac potassium channels in drug induced long QT syndrome. We also support the consensus that despite the availability of machine measurements of the QT interval, manual measurements should also be performed.