Current concepts in the mechanisms and management of drug-induced QT prolongation and torsade de pointes

Concentration-QTc Modeling of the DPP-4 Inhibitor HSK7653 in a First-in-Human Study of Chinese Healthy Volunteers

Cofrogliptin (HSK7653) is a long-acting dipeptidyl peptidase-4 inhibitor for the treatment of type 2 diabetes mellitus with a twice-monthly dosing regimen. This study included 62 participants (48 without food effect, 14 with food effect) receiving single doses of HSK7653 (5, 10, 25, 50, 100, and 150 mg) or placebo. Pharmacokinetic samples were collected over 24 hours postdosing and sampling times are aligned with 12-lead electrocardiograms (ECGs) which were derived from continuous ECG recordings. For the concentration-QT interval corrected for heart rate (C-QTc) analysis, we used linear mixed-effects modeling to characterize the correlation between plasma concentrations of HSK7653 and the change from baseline in the QT interval which was corrected by Fridericia's formula (ΔQTcF). The result showed that a placebo-corrected Fridericia corrected QT interval (ΔΔQTcF) prolongation higher than 10 milliseconds is unlikely at the mean maximum observed concentration (Cmax) (411 ng/mL) associated with the recommended therapeutic doses (25 mg twice-monthly), even at the highest supratherapeutic concentration (2425 ng/mL). Thus, HSK7653 does not significantly affect QT prolongation at either recommended doses or the highest supratherapeutic concentration.

Etiologies, Mechanisms, Management, and Outcomes of Electrical Storm

Electrical storm (ES) is characterized by three or more discrete sustained ventricular tachyarrhythmia episodes occurring within a limited time frame (generally ≤ 24 h) or an incessant ventricular tachyarrhythmia lasting > 12 h. In patients with an implantable cardioverterdefibrillator (ICD), ES is defined as three or more appropriate device therapies, separated from each other by at least 5 min, which occur within a 24-h period. ES may constitute a medical emergency, depending on the number arrhythmic episodes, their duration, the type, and the cycle length of the ventricular arrhythmias, as well as the underlying ventricular function. This narrative review was facilitated by a search of MEDLINE to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and other clinically relevant studies. The search was limited to English-language reports published between 1999 and 2023. ES was searched using the terms mechanisms, genetics, channelopathies, management, pharmacological therapy, sedation, neuraxial modulation, cardiac sympathetic denervation, ICDs, and structural heart disease. Google and Google scholar as well as bibliographies of identified articles were reviewed for additional references. This manuscript examines the current strategies available to treat ES and compares pharmacological and invasive treatment strategies to diminish ES recurrence, morbidity, and mortality.

Practical solutions for including sex as a biological variable (SABV) in preclinical neuropsychopharmacological research

Recently, many funding agencies have released guidelines on the importance of considering sex as a biological variable (SABV) as an experimental factor, aiming to address sex differences and avoid possible sex biases to enhance the reproducibility and translational relevance of preclinical research. In neuroscience and pharmacology, the female sex is often omitted from experimental designs, with researchers generalizing male-driven outcomes to both sexes, risking a biased or limited understanding of disease mechanisms and thus potentially ineffective therapeutics. Herein, we describe key methodological aspects that should be considered when sex is factored into in vitro and in vivo experiments and provide practical knowledge for researchers to incorporate SABV into preclinical research. Both age and sex significantly influence biological and behavioral processes due to critical changes at different timepoints of development for males and females and due to hormonal fluctuations across the rodent lifespan. We show that including both sexes does not require larger sample sizes, and even if sex is included as an independent variable in the study design, a moderate increase in sample size is sufficient. Moreover, the importance of tracking hormone levels in both sexes and the differentiation between sex differences and sex-related strategy in behaviors are explained. Finally, the lack of robust data on how biological sex influences the pharmacokinetic (PK), pharmacodynamic (PD), or toxicological effects of various preclinically administered drugs to animals due to the exclusion of female animals is discussed, and methodological strategies to enhance the rigor and translational relevance of preclinical research are proposed.

Bradycardia-Induced Torsades de Pointes in Atrioventricular Block

Bradycardia is known to prolong QT interval. Persistent bradycardia and high-grade atrioventricular (AV) block may lead to persistently prolonged QTc interval with a risk for life-threatening ventricular arrhythmias, which needs addressing the underlying cause. We present the case of a patient with persistent sinus bradycardia with a high-grade AV block leading to persistently prolonged QTc without any reversible etiology that resulted in torsades de pointes. The underlying treatment involved shortening the QTc by increasing the heart rate to prevent any further episodes of polymorphic ventricular tachycardia.

Long-acting opioids and cardiovascular diseases: Help or hindrance!

Opioids are widely being used for chronic pain management, cough and diarrhea suppressants, anesthetic agents, and opioid de-addiction therapy. Opioid receptors, present in the central nervous system and peripheral tissues, are documented to regulate several cardiac functions through different signaling pathways. Long-acting opioids (LAO) have been successfully evaluated for their beneficial effects in various cardiovascular diseases viz. myocardial infarction, ischemic reperfusion injuries, atherosclerosis etc. However, on the other hand, several research studies pointed towards the harmful effects of LAOs which are mainly associated with QTc prolongation, torsade de pointes, ventricular arrhythmias, and cardiac arrest. This review shall familiarize readers with the benefits as well as the harmful effects of long-acting opioids in cardiovascular diseases. We have also provided an overview of cardiac opioid receptors, endogenous cardiac opioid peptides, and regulation of cardiovascular functions by central and cardiac opioid receptors.

Enzastaurin cardiotoxicity: QT interval prolongation, negative inotropic responses and negative chronotropic action

Several clinical trials observed that enzastaurin prolonged QT interval in cancer patients. However, the mechanism of enzastaurin-induced QT interval prolongation is unclear. Therefore, this study aimed to assess the effect and mechanism of enzastaurin on QT interval and cardiac function. The Langendorff and Ion-Optix MyoCam systems were used to assess the effects of enzastaurin on QT interval, cardiac systolic function and intracellular Ca²⁺ transient in guinea pig hearts and ventricular myocytes. The effects of enzastaurin on the rapid delayed rectifier (I_Kr), the slow delayed rectifier K⁺ current (I_Ks), transient outward potassium current (I_to), action potentials, Ryanodine Receptor 2 (RyR2) and the sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a (SERCA2a) expression and activity in HEK 293 cell system and primary cardiomyocytes were investigated using whole-cell recording technique and western blotting. We found that enzastaurin significantly prolonged QT interval in guinea pig hearts and increased the action potential duration (APD) in guinea pig cardiomyocytes in a dose-dependent manner. Enzastaurin potently inhibited I_Kr by binding to the human Ether-à-go-go-Related gene (hERG) channel in both open and closed states, and hERG mutant channels, including S636A, S631A, and F656V attenuated the inhibitory effect of enzastaurin. Enzastaurin also moderately decreased I_Ks. Additionally, enzastaurin also induced negative chronotropic action. Moreover, enzastaurin impaired cardiac systolic function and reduced intracellular Ca²⁺ transient via inhibition of RyR2 phosphorylation. Taken together, we found that enzastaurin prolongs QT, reduces heart rate and impairs cardiac systolic function. Therefore, we recommend that electrocardiogram (ECG) and cardiac function should be continuously monitored when enzastaurin is administered to cancer patients.

The mechanism and treatment of targeted anti-tumour drugs induced cardiotoxicity

As the intensive anti-tumour therapy and combination of multiple anti-tumour drugs, cardiotoxicity events caused by anti-tumour drugs have also increased significantly, and the incidence of cardiotoxicity also increased with survival time. Different types of anti-tumour drugs could cause all kinds of cardiotoxicity which increase the difficulties in treatment and even live threatening. In this review, we concentrated in the targeted anti-tumour drugs such as human epidermal growth factor receptor-2 (HER2) inhibitors, tyrosine kinase inhibitors (TKIs), immune checkpoint inhibitors (ICIs), and proteasome inhibitors (Pls). The molecular mechanism of how these drugs induce cardiotoxicity is introduced which includes several signal pathways. These drugs induced cardiotoxicity involved heart failure, hypertension, atherosis and thrombosis, QT interval prolongation, and myocarditis. Some of the cardiotoxicity could be moderate and reversible but others could have happened severely.The aim of this review is to summarise the targeted anti-tumour drugs induced cardiotoxicity and treatment strategies.

Melatonin ameliorates arsenic-induced cardiotoxicity through the regulation of the Sirt1/Nrf2 pathway in rats

Chronic arsenic (As) exposure, mainly as a result of drinking contaminated water, is associated with cardiovascular diseases. Mitochondrial dysfunction, oxidative stress, inflammation, apoptosis, and autophagy have been suggested as the molecular etiology of As cardiotoxicity. Melatonin (Mel) is a powerful antioxidant. Mel improves diabetic cardiomyopathy, cardiac remodeling, and heart failure. Following pre-treatment with Mel (10, 20, or 30 mg/kg/day i.p.), rats were orally gavaged with As (15 mg/kg/day) for 28 days. Electrocardiographic findings showed that Mel decreased the As-mediated QT interval prolongation. The effects of As on cardiac levels of glutathione (GSH) and malondialdehyde (MDA) were reversed by Mel pretreatment. Mel also modulated the Sirt1 and Nrf2 expressions promoted by As. Mel down-regulated autophagy markers such as Beclin-1 expression and the LC3-II/I ratio. Moreover, the cardiac expression of cleaved-caspase-3 and Bax/Bcl-2 ratio was decreased by Mel pretreatment. Reduced expression of miR-34a and miR-144 by As were reversed by Mel. The histopathological changes of cardiac injury associated with As exposure was moderated by Mel. Mel may improve As-induced cardiac dysfunction through anti-oxidative, anti-apoptotic, and anti-autophagic mechanisms.

Early GLS changes detection after chemoradiation in locally advanced non-small cell lung cancer (NSCLC)

PURPOSE

Chemoradiation is the standard treatment in patients with locally advanced non-small-cell lung cancer (LA-NSCLC), and thanks to the recent combination with immunotherapy, median survival has unexpectedly improved. This study aims to evaluate early changes in cardiac function after chemoradiotherapy (CRT) in LA-NSCLC by multimodal use of advanced imaging techniques.

MATERIALS AND METHODS

This is a prospective, observational cohort study. At the beginning of combined treatment, screening tests including blood samples, electrocardiogram (ECG), echocardiographic examination (TTE), and cardiac magnetic resonance were performed in all patients with LA-NSCLC. ECG and cardiac marker assays were performed weekly during treatment. ECG and TTE were performed at month 1 (M1) and month 3 (M3) after the end of CRT.

RESULTS

This preliminary analysis included thirty-four patients with a mean age of 69.5 years. The median follow-up was 27.8 months. 62% of patients were in stage IIIA. Radiation therapy was delivered with a median total dose of 60 Gy with conventional fractionation. All patients were treated with concurrent CRT, and 65% of cases were platinum-based therapy. Global longitudinal strain (GLS) and ejection fraction (EF) progressively decreased from baseline to M1 and M3. There was a strong correlation between GLS and EF reduction (at M1: p = 0.034; at M3: p = 0.018). Cardiac arrhythmias occurred in eight patients (23.5%) at a mean follow-up of 15.8 months after CRT.

CONCLUSIONS

Reduction in GLS is an early sign occurring after the end of CRT for LA-NSCLC. Future studies are needed to identify variables that can increase the risk of cardiac events in this patient population to implement adequate damage prevention strategies.

Intramyocardial adenoviral vascular endothelial growth factor-D∆N∆C gene therapy does not induce ventricular arrhythmias

BACKGROUND

Phase I KAT301 trial investigated the use of intramyocardial adenoviral vascular endothelial growth factor -D^ΔNΔC (AdVEGF-D) gene therapy (GT) to alleviate symptoms in refractory angina (RA) patients. In KAT301, 30 patients with RA were randomized to AdVEGF-D or control group in 4:1 ratio. The treatment was found feasible, increased myocardial perfusion, and reduced angina symptoms at 1-year follow-up. However, there is some evidence suggesting that intramyocardial delivery route and overexpression of VEGFs might induce ventricular arrhythmias. Thus, we investigated whether intramyocardial AdVEGF-D GT increases the risk of ventricular arrhythmias in patients treated for RA.

METHODS

We analyzed non-invasive risk predictors of ventricular arrhythmias from 12-lead electrocardiography (ECG) as well as heart rate variability (HRV) and the incidence of arrhythmias from 24 h ambulatory ECG at baseline and 3 and 12 months after the GT. In addition, we analyzed the incidence of new-onset arrhythmias and pacemaker implantations during 8.2-year (range 6.3 - 10.4 years) follow-up.

RESULTS

We found no significant increase in arrhythmias, including supraventricular and ventricular ectopic beats, atrial fibrillation, non-sustained ventricular tachycardias, and life-threatening tachycardias, nor changes in the non-invasive risk predictors of ventricular arrhythmias in the AdVEGF-D treated patients. Instead, we found a significant improvement in the very low and high-frequency bands of HRV suggestive of improved cardiac autonomic regulation after GT.

CONCLUSIONS

In conclusion, our results suggest that AdVEGF-D GT does not predispose to arrhythmias and might improve HRV metrics.

Antioxidants in Arrhythmia Treatment—Still a Controversy? A Review of Selected Clinical and Laboratory Research

Antioxidants are substances that can prevent damage to cells caused by free radicals. Production of reactive oxygen species and the presence of oxidative stress play an important role in cardiac arrhythmias. Currently used antiarrhythmic drugs have many side effects. The research on animals and humans using antioxidants (such as vitamins C and E, resveratrol and synthetic substances) yields many interesting but inconclusive results. Natural antioxidants, such as vitamins C and E, can reduce the recurrence of atrial fibrillation (AF) after successful electrical cardioversion and protect against AF after cardiac surgery, but do not affect the incidence of atrial arrhythmias in critically ill patients with trauma. Vitamins C and E may also effectively treat ventricular tachycardia, ventricular fibrillation and long QT-related arrhythmias. Another natural antioxidant—resveratrol—may effectively treat AF and ventricular arrhythmias caused by ischaemia–reperfusion injury. It reduces the mortality associated with life-threatening ventricular arrhythmias and can be used to prevent myocardial remodelling. Statins also show antioxidant activity. Their action is related to the reduction of oxidative stress and anti-inflammatory effect. Therefore, statins can reduce the post-operative risk of AF and may be useful in lowering its recurrence rate after successful cardioversion. Promising results also apply to polyphenols, nitric oxide synthase inhibitors and MitoTEMPO. Although few clinical trials have been conducted, the use of antioxidants in treating arrhythmias is an interesting prospect.

Strategies for Transfer From Methadone to Buprenorphine for Treatment of Opioid Use Disorders and Associated Outcomes: A Systematic Review

OBJECTIVES

To review the currently available evidence on transfer strategies from methadone to sublingual buprenorphine used in clinical trials and observational studies of medication for opioid use disorder treatment, and to consider whether any strategies yield better clinical outcomes than others.

METHODS

Six medical and public health databases were searched for articles and conference abstracts. The Cochrane Central Register of Controlled Trials and the World Health Organization International Clinical Trials Registry Platform were used to identify unpublished trial results. Records were dually screened, and data were extracted and checked independently. Results were summarized qualitatively and, when possible, analyzed quantitatively.

RESULTS

Eighteen studies described transfer from methadone to buprenorphine. Transfer protocols were extremely varied. Most studies reported successful rates of transfer, even among studies involving transfer from high methadone doses, although lower pretransfer methadone dose was significantly associated with higher rate of successful transfer. Precipitated withdrawal was not reported frequently. A range of innovative approaches to transfer from methadone to buprenorphine remains untested.

CONCLUSIONS

Few studies have used designs that enable comparison of different approaches to transfer patients from methadone to buprenorphine. Most international clinical guidelines provide recommendations consistent with the available evidence. However, clinical guidelines should be perceived as providing "guidance" rather than "protocols," and clinicians and patients need to exercise judgment when attempting transfers.

Electrocardiogram abnormalities in antimony exposed workers in the automotive brake lining manufacturing industry: a case report

Background

Antimony is used in catalysts, pesticides, brake systems, pharmaceuticals, and synthetic fire retardants in the plastic, paint, and rubber industries. Accumulation of trivalent antimony compounds in the body can cause cardiotoxic effects and increase the risk of electrocardiogram (ECG) abnormalities and sudden death. Antimony exposure can result in action potential prolongation, causing a cardiac repolarization delay, which appears as QTc prolongation and T-wave abnormalities on the ECG. There are no studies on antimony-associated cardiac toxicity in Korea.

Case presentation

Accordingly, the present study reports cases of ECG abnormalities in workers handling antimony trisulfide at a company located in the Gyeongsangbuk-do region. Nineteen workers employed at an automobile brake lining manufacturer were exposed to antimony trisulfide dust through thermoforming, grinding, and drilling processes. In 2020, the workers were reported to work 12-hour shifts, 5 days a week. The time-weighted average (TWA) of antimony trisulfide exposure measured in workers was 0.0028 mg/m³. Two workers were excluded from the analysis due to pre-existing medical conditions (cardiovascular disease). Of the remaining 17 workers, ECG abnormalities were found in 41% (seven out of 17: four with QTc prolongation and T-wave abnormalities; two with only T-wave abnormalities; and one with only QTc prolongation).

Conclusions

This case report outlines the first few cases in Korea in which potential cardiac toxicity caused by occupational exposure to antimony was identified. However, data regarding cardiac toxicity caused by antimony exposure are still lacking in Korea; thus, additional studies are needed to identify causal relationships.

Transient Hypogonadism Is Associated With Heart Rate-Corrected QT Prolongation and Torsades de Pointes Risk During Active Systemic Inflammation in Men

Background

Systemic inflammation and male hypogonadism are 2 increasingly recognized “nonconventional” risk factors for long‐QT syndrome and torsades de pointes (TdP). Specifically, inflammatory cytokines prolong, while testosterone shortens the heart rate–corrected QT interval (QTc) via direct electrophysiological effects on cardiomyocytes. Moreover, several studies demonstrated important interplays between inflammation and reduced gonad function in men. We hypothesized that, during inflammatory activation in men, testosterone levels decrease and that this enhances TdP risk by contributing to the overall prolonging effect of inflammation on QTc.

Methods and Results

We investigated (1) the levels of sex hormones and their relationship with inflammatory markers and QTc in male patients with different types of inflammatory diseases, during active phase and recovery; and (2) the association between inflammatory markers and sex hormones in a cohort of male patients who developed extreme QTc prolongation and TdP, consecutively collected over 10 years. In men with active inflammatory diseases, testosterone levels were significantly reduced, but promptly normalized in association with the decrease in C‐reactive protein and interleukin‐6 levels. Reduction of testosterone levels, which also inversely correlated with 17‐β estradiol over time, significantly contributed to inflammation‐induced QTc prolongation. In men with TdP, both active systemic inflammation and hypogonadism were frequently present, with significant correlations between C‐reactive protein, testosterone, and 17‐β estradiol levels; in these patients, increased C‐reactive protein and reduced testosterone were associated with a worse short‐term outcome of the arrhythmia.

Conclusions

During systemic inflammatory activation, interleukin‐6 elevation is associated with reduced testosterone levels in males, possibly deriving from an enhanced androgen‐to‐estrogen conversion. While transient, inflammatory hypotestosteronemia is significantly associated with an increased long‐QT syndrome/TdP risk in men.

Mechanisms of gefitinib-induced QT prolongation

Gefitinib, a tyrosine kinase inhibitor, was the first targeted therapy for non-small cell lung cancer (NSCLC). Gefitinib could block human Ether-à-go-go-Related Gene (hERG) channel, an important target in drug-induced long QT syndrome. However, it is unclear whether gefitinib could induce QT interval prolongation. Here, whole-cell patch-clamp technique was used for evaluating the effect of gefitinib on rapidly-activating delayed rectifier K⁺ current (I_Kr), slowly-activating delayed rectifier K⁺ current (I_Ks), transient outward potassium current (I_to), inward rectifier K⁺ current (I_K1) and on action potentials in guinea pig ventricular myocytes. The Langendorff heart perfusion technique was used to determine drug effect on the ECG. Gefitinib depressed I_Kr by binding to open and closed hERG channels in a concentration-dependent way (IC_50: 1.91 μM). The inhibitory effect of gefitinib on wildtype hERG channels was reduced at the hERG mutants Y652A, S636A, F656V and S631A (IC_50: 8.51, 13.97, 18.86, 32.99 μM), indicating that gefitinib is a pore inhibitor of hERG channels. In addition, gefitinib accelerated hERG channel inactivation and decreased channel steady-state inactivation. Gefitinib also decreased I_Ks with IC₅₀ of 23.8 μM. Moreover, gefitinib increased action potential duration (APD) in guinea pig ventricular myocytes and the corrected QT interval (QTc) in isolated perfused guinea pig hearts in a concentration-dependent way (1-30 μM). These findings indicate that gefitinib could prolong QTc interval by potently blocking hERG channel, modulating kinetic properties of hERG channel. Partial block of KCNQ1/KCNE1 could also contribute to delayed repolarization and prolonged QT interval. Thus, caution should be taken when gefitinib is used for NSCLC treatment.

Torsade de pointes: A nested case-control study in an integrated healthcare delivery system

Background

TdP is a form of polymorphic ventricular tachycardia which develops in the setting of a prolonged QT interval. There are limited data describing risk factors, treatment, and outcomes of this potentially fatal arrhythmia.

Objective

Our goals were as follows: (1) to validate cases presenting with Torsade de Pointes (TdP), (2) to identify modifiable risk factors, and (3) to describe the management strategies used for TdP and its prognosis in a real‐world healthcare setting.

Methods

Case–control study (with 2:1 matching on age, sex, and race/ethnicity) nested within the Genetic Epidemiology Research on Aging (GERA) cohort. Follow‐up of the cohort for case ascertainment was between January 01, 2005 and December 31, 2018.

Results

A total of 56 cases of TdP were confirmed (incidence rate = 3.6 per 100,000 persons/years). The average (SD) age of the TdP cases was 74 (13) years, 55 percent were female, and 16 percent were non‐white. The independent predictors of TdP were potassium concentration <3.6 mEq/L (OR = 10.6), prior history of atrial fibrillation/flutter (OR = 6.2), QTc >480 ms (OR = 4.4) and prior history of coronary artery disease (OR = 2.6). Exposure to furosemide and amiodarone was significantly greater in cases than in controls. The most common treatment for TdP was IV magnesium (78.6%) and IV potassium repletion (73.2%). The in‐hospital and 1‐year mortality rates for TdP cases were 10.7% and 25.0% percent, respectively.

Conclusions

These findings may inform quantitative multivariate risk indices for the prediction of TdP and could guide practitioners on which patients may qualify for continuous ECG monitoring and/or electrolyte replacement therapy.

Cross-Talks between the Cardiovascular Disease-Sarcopenia-Osteoporosis Triad and Magnesium in Humans

Magnesium (Mg) is a pivotal and very complex component of healthy aging in the cardiovascular-muscle-bone triad. Low Mg levels and low Mg intake are common in the general aging population and are associated with poorer outcomes than higher levels, including vascular calcification, endothelial dysfunction, osteoporosis, or muscle dysfunction/sarcopenia. While Mg supplementation appears to reverse these processes and benefit the triad, more randomized clinical trials are needed. These will allow improvement of preventive and curative strategies and propose guidelines regarding the pharmaceutical forms and the dosages and durations of treatment in order to optimize and adapt Mg prescription for healthy aging and for older vulnerable persons with comorbidities.

Melissa officinalis L. as a Nutritional Strategy for Cardioprotection

This review aimed to provide a summary on the traditional uses, phytochemistry, and pharmacological activities in the cardiovascular system and cardiotoxicity of Melissa officinalis (MO), with the special emphasis on the protective mechanisms in different cardiovascular pathologies. MO is a perennial aromatic herb commonly known as lemon balm, honey balm, or bee balm, which belongs to Lamiaceae family. Active components are mainly located in the leaves or essential oil and include volatile compounds, terpenoid (monoterpenes, sesquiterpenes, triterpenes), and polyphenolic compounds [rosmarinic acid (RA), caffeic acid, protocatechuic acid, quercitrin, rhamnocitrin, luteolin]. For centuries, MO has been traditionally used as a remedy for memory, cognition, anxiety, depression, and heart palpitations. Up until now, several beneficial cardiovascular effects of MO, in the form of extracts (aqueous, alcoholic, and hydroalcoholic), essential oil, and isolated compounds, have been confirmed in preclinical animal studies, such as antiarrhythmogenic, negative chronotropic and dromotropic, hypotensive, vasorelaxant, and infarct size-reducing effects. Nonetheless, MO effects on heart palpitations are the only ones confirmed in human subjects. The main mechanisms proposed for the cardiovascular effects of this plant are antioxidant free radical-scavenging properties of MO polyphenols, amelioration of oxidative stress, anti-inflammatory effects, activation of M2 and antagonism of β1 receptors in the heart, blockage of voltage-dependent Ca²⁺ channels, stimulation of endothelial nitric oxide synthesis, prevention of fibrotic changes, etc. Additionally, the main active ingredient of MO-RA, per se, has shown substantial cardiovascular effects. Because of the vastness of encouraging data from animal studies, this plant, as well as the main ingredient RA, should be considered and investigated further as a tool for cardioprotection and adjuvant therapy in patients suffering from cardiovascular diseases.

Progress in the risk assessment of hydroxychloroquine in frail elderly people

Hydroxychloroquine (HCQ) is an antimalarial drug also known to have anti-inflammatory and antiviral effects. The antiviral action of HCQ has been a point of interest for many researchers because of its mechanism of action and the potential use it could have during the current COVID-19 pandemic. However, HCQ can cause QT interval prolongation. The current therapies used in COVID-19 are changing as the pandemic develops. The aim of this article is to promote a validated risk score for QT prolongation in multidimensional assessment of COVID-19 patients, especially in elderly and polypathological patients.

QTc interval prolongation in patients with systemic lupus erythematosus treated with hydroxychloroquine

OBJECTIVES

The primary objective is to reveal the effect of hydroxychloroquine (HCQ) treatment on corrected QT (QTc) interval in patients with systemic lupus erythematosus (SLE). The secondary objective is to investigate factors that affect QTc prolongation.

METHODS

SLE patients who had electrocardiograms between 2015 and 2020 were recruited and assigned to two groups based on whether they were treated with HCQ (HCQ group) or not (control group). Change of QTc before and after HCQ administration in the HCQ group was measured and compared with the control group. Patients treated with HCQ were further divided into two groups based on presence or absence of QTc prolongation and the characteristics were compared.

RESULTS

In total, 126 patients were recruited, of whom 42 were treated with HCQ. In the HCQ group, the mean QTc significantly increased (p < .001), while there was no significant difference of mean QTc in the control group. Moreover, those in the HCQ group with QTc prolongation showed a significantly higher proportion of hypertension and longer SLE duration compared to those without QTc prolongation. However, the multiple logistic regression analysis showed that there were no significant differences among them.

CONCLUSION

HCQ could induce QTc prolongation in SLE patients. It might be better that the possibility of QTc prolongation was taken into consideration when HCQ was administered in the patients with longer disease duration of SLE and coincidence of hypertension.

Magnesium in Aging, Health and Diseases

Several changes of magnesium (Mg) metabolism have been reported with aging, including diminished Mg intake, impaired intestinal Mg absorption and renal Mg wasting. Mild Mg deficits are generally asymptomatic and clinical signs are usually non-specific or absent. Asthenia, sleep disorders, hyperemotionality, and cognitive disorders are common in the elderly with mild Mg deficit, and may be often confused with age-related symptoms. Chronic Mg deficits increase the production of free radicals which have been implicated in the development of several chronic age-related disorders. Numerous human diseases have been associated with Mg deficits, including cardiovascular diseases, hypertension and stroke, cardio-metabolic syndrome and type 2 diabetes mellitus, airways constrictive syndromes and asthma, depression, stress-related conditions and psychiatric disorders, Alzheimer's disease (AD) and other dementia syndromes, muscular diseases (muscle pain, chronic fatigue, and fibromyalgia), bone fragility, and cancer. Dietary Mg and/or Mg consumed in drinking water (generally more bioavailable than Mg contained in food) or in alternative Mg supplements should be taken into consideration in the correction of Mg deficits. Maintaining an optimal Mg balance all through life may help in the prevention of oxidative stress and chronic conditions associated with aging. This needs to be demonstrated by future studies.

Acute Ramelteon Treatment Maintains the Cardiac Rhythms of Rats during Non-REM Sleep

Sleep curtailment negatively affects cardiac activities and thus should be ameliorated by pharmacological methods. One of the therapeutic targets is melatonin receptors, which tune circadian rhythms. Ramelteon, a melatonin MT1/MT2 receptor agonist, has recently been developed to modulate sleep-wake rhythms. To date, the sleep-promoting effect of ramelteon has been widely delineated, but whether ramelteon treatment physiologically influences cardiac function is not well understood. To address this question, we recorded electrocardiograms, electromyograms, and electrocorticograms in the frontal cortex and the olfactory bulb of unrestrained rats treated with either ramelteon or vehicle. We detected vigilance states based on physiological measurements and analyzed cardiac and muscular activities. We found that during non-rapid eye movement (non-REM) sleep, heartrate variability was maintained by ramelteon treatment. Analysis of the electromyograms confirmed that neither microarousal during non-REM sleep nor the occupancy of phasic periods during REM sleep was altered by ramelteon. Our results indicate that ramelteon has a remedial effect on cardiac activity by keeping the heartrate variability and may reduce cardiac dysfunction during sleep.

Preliminary evaluation of the efficacy of intravenous magnesium sulfate for the treatment of ventricular arrhythmias in 16 dogs

OBJECTIVE

To evaluate the efficacy of IV magnesium sulfate in decreasing the number of ventricular ectopic beats or convert ventricular tachyarrhythmia to sinus rhythm in dogs.

DESIGN

Prospective, observational feasibility study.

SETTING

Private referral center.

ANIMALS

Sixteen client-owned dogs exhibiting 1 or more of the following: (1) sustained or paroxysmal ventricular tachycardia (heart rate > 180/min), (2) single or multiform ventricular complexes at > 60 ectopies/min.

INTERVENTIONS

Pretreatment (T1) blood creatinine and electrolyte concentrations were measured. A 60-second lead II ECG strip and systolic arterial blood pressure (SABP) were recorded. Magnesium sulfate 0.1 mmol/kg (0.2 mEq/kg) was administered IV over 5 minutes. Five minutes after completion of the magnesium sulfate injection (T2), electrolyte concentrations were measured again. A second 60-second lead II ECG strip and SABP were recorded. The number of ectopic ventricular and supraventricular beats (sinus beats) that occurred in 60 seconds during the T1 and T2 ECG recordings was compared. T1 and T2 electrolytes and SABP were also compared.

RESULTS

There was an increase in the ionized magnesium concentration, a decrease in the heart rate and the number of ventricular ectopic beats, and an increase in the number of supraventricular beats at T2. Two dogs converted to a sinus rhythm at T2 that was not sustained.

CONCLUSIONS

Intravenous administration of 0.1 mmol/kg (0.2 mEq/kg) magnesium sulfate in dogs with ventricular ectopy decreased the number of ventricular beats and heart rate. However, a specific conclusion regarding the use of magnesium sulfate as a first-line therapy for dogs with ventricular tachyarrhythmias at the investigated dose cannot be made.

Polymorphic Ventricular Tachycardia Associated with High-Dose Methadone Use

Methadone is a well-tolerated drug that has been used for pain control and the treatment of opioid addiction. However, some fatal cardiac side effects have been reported previously, including ventricular arrhythmia, stress cardiomyopathy, and coronary artery disease. We reported a middle-aged woman receiving high-dose methadone whom was presented with QT prolongation and torsade de pointes. We replaced the methadone with benzodiazepine and gave lidocaine use simultaneously. Thus, QT interval was shortened within the normal limit. Methadone-induced torsade de pointes is a rare but serious event, and QT interval should be monitored periodically to prevent this fatal adverse event, especially some patients with high-dose methadone use.

Magnesium, Oxidative Stress, Inflammation, and Cardiovascular Disease

Hypomagnesemia is commonly observed in heart failure, diabetes mellitus, hypertension, and cardiovascular diseases. Low serum magnesium (Mg) is a predictor for cardiovascular and all-cause mortality and treating Mg deficiency may help prevent cardiovascular disease. In this review, we discuss the possible mechanisms by which Mg deficiency plays detrimental roles in cardiovascular diseases and review the results of clinical trials of Mg supplementation for heart failure, arrhythmias and other cardiovascular diseases.

The effect of 5-day course of hydroxychloroquine and azithromycin combination on QT interval in non-ICU COVID19(+) patients

BACKGROUND

The combination of Hydroxychloroquine (HCQ) and azithromycin showed effectiveness as a treatment for COVID-19 and is being used widely all around the world. Despite that those drugs are known to cause prolonged QT interval individually there is no study assessing the impact of this combination on electrocardiography (ECG). This study aimed to assess the impact of a 5-day course of HCQ and azithromycin combination on ECG in non-ICU COVID19(+) patients.

METHODS

In this retrospective observational study, we enrolled 109 COVID19(+) patients who required non-ICU hospitalization. All patients received 5-day protocol of HCQ and azithromycin combination. On-treatment ECGs were repeated 3-6 h after the second HCQ loading dose and 48-72 h after the first dose of the combination. ECGs were assessed in terms of rhythm, PR interval, QRS duration, QT and QTc intervals. Baseline and on-treatment ECG findings were compared. Demographic characteristics, laboratory results were recorded. Daily phone call-visit or bed-side visit were performed by attending physician.

RESULTS

Of the 109 patients included in the study, the mean age was 57.3 ± 14.4 years and 48 (44%) were male. Mean baseline PR interval was 158.47 ± 25.10 ms, QRS duration was 94.00 ± 20.55 ms, QTc interval was 435.28 ± 32.78 ms, 415.67 ± 28.51, 412.07 ± 25.65 according to Bazett's, Fridericia's and Framingham Heart Study formulas respectively. ∆PR was -2.94 ± 19.93 ms (p = .55), ∆QRS duration was 5.18 ± 8.94 ms (p = .03). ∆QTc interval was 6.64 ± 9.60 ms (p = .5), 10.67 ± 9.9 ms (p = .19), 14.14 ± 9.68 ms (p = .16) according to Bazett's, Fridericia's and Framingham Heart Study formulas respectively. There were no statistically significant differences between QTc intervals. No ventricular tachycardia, ventricular fibrillation or significant conduction delay was seen during follow-up. There was no death or worsening heart function.

CONCLUSION

The 5-day course of HCQ- AZM combination did not lead to clinically significant QT prolongation and other conduction delays compared to baseline ECG in non-ICU COVID19(+) patients.

Relationship between antofloxacin concentration and QT prolongation and estimation of the possible false-positive rate

PURPOSE

To elucidate the relationship between antofloxacin (AT) plasma concentration and QT interval prolongation, compare the effects of different correction and analytical methods on conclusions, and estimate the possible false-positive rate in thorough QT (TQT) studies.

METHODS

Twenty-four healthy Chinese volunteers from a four-period crossover TQT study orally received 200 mg/d AT, 400 mg/d AT, 400 mg/d moxifloxacin, and a placebo in a random order for 5 d for each. QT interval samples were collected on d 1 and d 5. Population models were established describing the relationship between QT and AT concentration. The yardstick from ICH E14 guidelines was used to measure the effect of drugs on QT prolongation both in biostatistical and modeling analyses. A possible false-positive rate was estimated by constructing a 1000-time bootstrap to obtain the rate-of-difference values between d 1 and d 5 over 5 ms in the placebo period.

RESULTS

In the modeling analysis, the QT prolongation estimate at the mean maximal concentration of AT (4.51 μg/mL) was 3.84 ms, and its upper bound of the one-sided 95 % CI was 7.04 ms, which showed a negative effect on QT interval prolongation. The estimation for the false-positive rate was 31 % in this study.

CONCLUSION

The effect of AT on QT interval prolongation may not have been significant at the dosage of 400 mg. Baseline and placebo adjustments were necessary in TQT studies. Population modeling has demonstrated clear superiority in making full use of data to accurately analyze the relationship between drugs and QT intervals.

Pharmacogenomics of methadone: a narrative review of the literature

Background: Methadone, a synthetic opioid with longer duration of action and lower abuse potential compared with morphine, is used to prevent opioid withdrawal, as well as to manage chronic and acute surgical pain. The variability in response to methadone has been widely recognized. The purpose of this article is to review the literature on the pharmacogenetic factors underlying this variability. Materials & methods: This is a narrative overview of the literature on the genetic variants affecting pharmacodynamics and pharmacokinetics of methadone, retrieved from searches of databases such as PubMed and google scholar. Discussion: Clinical responses to methadone may be affected by genetic variants in the opioidergic, dopaminergic and neurotrophic pathways. Polymorphisms in genes related to disposition and elimination of methadone alter the pharmacokinetics, and possibly pharmacodynamics of methadone. Cytochrome P450 enzymes and P-glycoprotein variants contribute to the interindividual variability in methadone pharmacokinetics. Evidence for single gene variants affecting methadone response remains weak. Multiple genetic variants must be considered in conjunction to improve predictive ability. Conclusion: Evidence remains scarce at this time, to recommend pharmacogenetic testing before methadone administration. Well-powered clinical studies are needed with population pharmacokinetic-pharmacodynamic modeling and multigenetic signature-based predictions to enable tailored use of methadone in clinical practice.

Cardiac Arrest Risk During Acute Infections: Systemic Inflammation Directly Prolongs QTc Interval via Cytokine-Mediated Effects on Potassium Channel Expression

BACKGROUND

During acute infections, the risk of malignant ventricular arrhythmias is increased, partly because of a higher propensity to develop QTc prolongation. Although it is generally believed that QTc changes almost exclusively result from concomitant treatment with QT-prolonging antimicrobials, direct effects of inflammatory cytokines on ventricular repolarization are increasingly recognized. We hypothesized that systemic inflammation per se can significantly prolong QTc during acute infections, via cytokine-mediated changes in K⁺ channel expression.

METHODS

We evaluated (1) the frequency of QTc prolongation and its association with inflammatory markers, in patients with different types of acute infections, during active disease and remission; (2) the prevalence of acute infections in a cohort of consecutive patients with Torsades de Pointes; (3) the relationship between K⁺ channel mRNA levels in ventricles and peripheral blood mononuclear cells and their changes in patients with acute infection over time.

RESULTS

In patients with acute infections, regardless of concomitant QT-prolonging antimicrobial treatments, QTc was significantly prolonged but rapidly normalized in parallel to CRP (C-reactive protein) and cytokine level reduction. Consistently in the Torsades de Pointes cohort, concomitant acute infections were highly prevalent (30%), despite only a minority (25%) of these cases were treated with QT-prolonging antimicrobials. KCNJ2 K⁺ channel expression in peripheral blood mononuclear cell, which strongly correlated to that in ventricles, inversely associated to CRP and IL (interleukin)-1 changes in acute infection patients.

CONCLUSIONS

During acute infections, systemic inflammation rapidly induces cytokine-mediated ventricular electrical remodeling and significant QTc prolongation, regardless concomitant antimicrobial therapy. Although transient, these changes may significantly increase the risk of life-threatening ventricular arrhythmia in these patients. It is timely and warranted to transpose these findings to the current coronavirus disease 2019 (COVID-19) pandemic, in which both increased amounts of circulating cytokines and cardiac arrhythmias are demonstrated along with a frequent concomitant treatment with several QT-prolonging drugs. Graphic Abstract: A graphic abstract is available for this article.

Angiotensin receptor-neprilysin inhibitior (thiorphan/irbesartan) decreased ischemia-reperfusion induced ventricular arrhythmias in rat; in vivo study

Ventricular arrhythmias are considered as a major risk of sudden cardiac death. This study was designed to investigate the potential effects of angiotensin receptor neprilysin inhibitor; thiorphan/irbesartan (TH/IRB) combination therapy on myocardial ischemic-reperfusion (I/R)-induced arrhythmia. Fifty male Wistar rats were divided into 5 groups; (I, II): Sham, I/R both received DMSO intraperitoneally before the procedure. (III, IV, V): TH/IRB + IR (0.1/5 mg/kg, 0.1/10 mg/kg and 0.1/15 mg/kg). The drugs were injected intraperitoneally 15 min before I/R induction. Electrocardiograms changes, mean arterial blood pressure, incidence of ventricular tachycardia (VT), incidence of ventricular fibrillation (VF) and arrhythmia score were assessed. Cardiac levels of creatinine kinase-MB (CK-MB), Malondialdehyde (MDA), superoxide dismutase (SOD), endothelin-1 (ET-1), ATP content, and Na⁺/K⁺-ATPase pump activity were measured. TH (0.1 mg/kg) in combination with IRB (5, 10 and 15 mg/kg) produced significant decrease in QTc interval duration, ST height, incidence of VT and VF, duration of VT + VF, and arrhythmia score compared to I/R group. All treated groups showed significant decrease in the cardiac levels of: CK-MB, MDA and ET-1 and significant increase in SOD, ATP content, and Na⁺/K⁺-ATPase pump activity compared to I/R. TH/IRB + IR (0.1/10 mg/kg) group produced significant decrease in CK-MB, MDA and ET-1 and a significant increase in SOD, ATP content, and Na⁺/K⁺-ATPase pump activity compared to other treated groups. In conclusion, angiotensin receptor neprilysin inhibitor (thiorphan/irbesartan) decreased arrhythmia score and decreased cardiac damage. These could be explained in part by its ability to decrease oxidative stress and ET-1, increase ATP, and Na⁺/K⁺-ATPase pump activity in this rat model of I/R-induced arrhythmia.

Predictive Validity of a QTc Interval Prolongation Risk Score in the Intensive Care Unit

BACKGROUND

Torsade de pointes is a form of polymorphic ventricular tachycardia associated with heart rate-corrected QT (QT_c ) interval prolongation. With approximately 24-61% of critically ill patients experiencing QT_c interval prolongation, a predictive tool to identify high-risk patients could assist in the monitoring and management in the intensive care unit (ICU). The Tisdale et al. Risk Score (TRS) is a predictive tool that was developed and validated in a cardiac critical care unit.

OBJECTIVES

The objective of this study was to evaluate the predictive validity (sensitivity and specificity) and likelihood ratios of the TRS in a medical ICU.

METHODS

This was a longitudinal, retrospective, cohort study of consecutive patients who met the inclusion criteria from October 2017 to June 2018 with a sample size of 264 patients. The sample size was derived based on the number of TRS covariates and an exploratory variable. Baseline characteristics and risk factors were documented from electronic health records. The first occurrence of QT_c interval prolongation, defined as a QT_c interval > 500 ms or an increase ≥ 60 ms above baseline, was the primary endpoint.

MAIN RESULTS

The sensitivity and specificity of the TRS for low-risk patients against the moderate-risk and high-risk patients were 97% (95% CI 91-99%) and 16% (95% CI 11-23%), respectively. These results corresponded to a positive likelihood ratio of 1.15 (95% CI 1.07-1.24) and a negative likelihood ratio of 0.20 (95% CI 0.06-0.65).

CONCLUSIONS

In conclusion, the TRS showed a high sensitivity, making it useful in identifying patients at risk of developing QT_c interval prolongation. Furthermore, patients categorized as low risk by the tool can be considered as having minimal risk of developing QT_c interval prolongation. Given the tool's low specificity, it does not reliably identify all patients at low risk of QT_c interval prolongation.

Classifying Drugs by their Arrhythmogenic Risk Using Machine Learning

All medications have adverse effects. Among the most serious of these are cardiac arrhythmias. Current paradigms for drug safety evaluation are costly, lengthy, conservative, and impede efficient drug development. Here, we combine multiscale experiment and simulation, high-performance computing, and machine learning to create a risk estimator to stratify new and existing drugs according to their proarrhythmic potential. We capitalize on recent developments in machine learning and integrate information across 10 orders of magnitude in space and time to provide a holistic picture of the effects of drugs, either individually or in combination with other drugs. We show, both experimentally and computationally, that drug-induced arrhythmias are dominated by the interplay between two currents with opposing effects: the rapid delayed rectifier potassium current and the L-type calcium current. Using Gaussian process classification, we create a classifier that stratifies drugs into safe and arrhythmic domains for any combinations of these two currents. We demonstrate that our classifier correctly identifies the risk categories of 22 common drugs exclusively on the basis of their concentrations at 50% current block. Our new risk assessment tool explains under which conditions blocking the L-type calcium current can delay or even entirely suppress arrhythmogenic events. Using machine learning in drug safety evaluation can provide a more accurate and comprehensive mechanistic assessment of the proarrhythmic potential of new drugs. Our study paves the way toward establishing science-based criteria to accelerate drug development, design safer drugs, and reduce heart rhythm disorders.

Classifying Drugs by their Arrhythmogenic Risk Using Machine Learning

All medications have adverse effects. Among the most serious of these are cardiac arrhythmias. Current paradigms for drug safety evaluation are costly, lengthy, conservative, and impede efficient drug development. Here, we combine multiscale experiment and simulation, high-performance computing, and machine learning to create a risk estimator to stratify new and existing drugs according to their proarrhythmic potential. We capitalize on recent developments in machine learning and integrate information across 10 orders of magnitude in space and time to provide a holistic picture of the effects of drugs, either individually or in combination with other drugs. We show, both experimentally and computationally, that drug-induced arrhythmias are dominated by the interplay between two currents with opposing effects: the rapid delayed rectifier potassium current and the L-type calcium current. Using Gaussian process classification, we create a classifier that stratifies drugs into safe and arrhythmic domains for any combinations of these two currents. We demonstrate that our classifier correctly identifies the risk categories of 22 common drugs exclusively on the basis of their concentrations at 50% current block. Our new risk assessment tool explains under which conditions blocking the L-type calcium current can delay or even entirely suppress arrhythmogenic events. Using machine learning in drug safety evaluation can provide a more accurate and comprehensive mechanistic assessment of the proarrhythmic potential of new drugs. Our study paves the way toward establishing science-based criteria to accelerate drug development, design safer drugs, and reduce heart rhythm disorders.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Mirtazapine's effect on the QT interval in medically hospitalized patients

Introduction

Mirtazapine is generally well tolerated in medically ill patients with and without formal psychiatric comorbidity to target sleep, appetite, nausea, and pain. However, there is little data regarding mirtazapine's potential to prolong the corrected QT interval (QTc) in this population.

Methods

From a retrospective cohort of patients hospitalized on a variety of medical units for whom a psychiatric consult recommended mirtazapine, electrocardiogram (ECG) data were extracted for ECGs obtained up to 3 days before and 6 days after the initial consult. Descriptive statistics were used to characterize the QTc changes and adverse cardiac outcomes, including incident ventricular tachycardia, torsades de pointes, and sudden cardiac death. Multiple linear regression models were completed to assess the effect of potential confounding variables on QTc changes.

Results

Complete premirtazapine and postmirtazapine ECG data were available for 61 patients, and the average change in QTc was –0.31 ms (SD = 36.62 ms). No incidental adverse cardiac outcomes were found. QTc changes were not significantly affected by patient age and sex, initial and maximum mirtazapine dose, days between ECGs, number of concomitant QTc prolonging medications, Charlson comorbidity scores, and electrolyte abnormalities. Due to incomplete potassium, magnesium, and ionized calcium data, electrolytes were excluded from the final regression model.

Discussion

Despite the limitations of this retrospective study, these data suggest that modest doses of mirtazapine may not significantly affect the QTc in medically ill patients. Retrospective cohorts are more feasibly analyzed, but prospective controlled trials could more systematically assess QTc changes with higher doses of mirtazapine in medical settings.

Drug interactions and creatinine levels are associated with QTc prolongation in intensive care units: a prospective, observational study

Background Prolongation of the QTc interval may lead to life threatening arrhythmias. QTc prolongation is common in intensive care unit (ICU) patients. The objectives of this study were to identify the role of drug-drug interactions (DDIs) and other predictors (age, sex, cardiovascular diseases, and electrolyte abnormalities) in life threatening QTc prolongation in patients admitted to medical (M), surgical (S) and emergency (E) ICUs. Methods This prospective, observational study included patients above the age of 18 years who were admitted to SICU, EICU, and MICU at a tertiary respiratory referral center. Electrocardiogram (ECG) monitoring was performed during the first 5 days of ICU admission. Risk factors and DDIs which were anticipated to be associated with the prolongation of the QTc interval were assessed for all patients. Results Two hundred patients were included in the study. QTc prolongation occurred in 10.7% of patients and the majority of patients presenting with QTc prolongation had creatinine levels above 1.3 mg/dL during their 5 days of ICU admission. Incidence of pharmacodynamic (PD) DDIs was significantly higher in patients with QTc prolongation vs. other patients. Creatinine levels above 1.3 mg/dL and PD DDIs were associated with QTc prolongation during 5 days of ICU admission. Conclusions High serum creatinine and PD DDIs can increase the risk of QTc prolongation in patients admitted to the ICU. QTc interval measurements should be performed prior to initiation or after starting any drug that is associated with QT prolongation, specifically in patients with the known risk factors.

Corrected QT Interval Prolongation in Pediatric and Young Adult Patients on Methadone for Cancer-Related Pain

CONTEXT

Methadone has been reported to prolong the corrected QT (QTc) interval and increase the risk of torsades de pointes.

OBJECTIVES

Our study examined the frequency of QTc prolongation among pediatric and young adult patients starting methadone for cancer pain.

METHODS

All patients followed a standardized protocol. Electrocardiograms (ECGs) were obtained at baseline (methadone starting day to 14 days prior), 1-2 weeks, and 4-6 weeks later. QTc values were manually calculated using the Bazett formula. QTc prolongation was defined as ≥460 milliseconds (ms) for prepubertal children, ≥470 ms for pubertal males, and ≥480 ms for pubertal females.

RESULTS

Baseline ECGs were completed in 42 patients. Follow-up ECGs were completed in 38 of 42 (91%) and 31 of 42 (74%) patients at 1-2 weeks and 4-6 weeks, respectively. No patients had prolongation of the QTc at baseline, and 1 of 38 (3%) patients had a prolonged QTc at weeks 1-2. This patient had a history of prolonged QTc that the family did not initially report. No patients had prolongation of the QTc at weeks 4-6. No patients had torsades de pointes or ventricular fibrillation, and none died suddenly. Median (interquartile range [IQR]) baseline QTc was 391 (377-400) ms; median (IQR) 1-2 week follow-up QTc was 399 (374-411) ms (P = .05), and median (IQR) 4-6 week follow-up QTc was 393 (379-423) ms (P = .01).

CONCLUSION

Clinically significant prolongation of the QTc interval occurred only in one patient who had a history of prolonged QTc. Prolonged QTc is rare in this population.

Proton pump inhibitor-induced hypomagnesemia complicated with serious cardiac arrhythmias

Introduction: Magnesium is the third most common intracellular ion after potassium and calcium and is an important element in the functions of the body, since it participates in more than 300 enzyme systems. It also, plays a significant role in the transport of calcium and potassium across the cell membranes and protects against cardiac arrhythmias and is useful for their treatment due to hypomagnesemia induced from the proton pump inhibitors (PPIs). Areas covered: PPIs are used for the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD), but have been associated with hypomagnesemia with serious cardiac arrhythmias including torsades de pointes (TdP). To better understand the magnitude of this problem, a Medline search of the English language literature was conducted from 2010 to 2018 and 35 papers with pertinent information were selected. Expert commentary: The review of these papers suggests that PPIs cause hypomagnesemia, which could be associated with serious cardiac arrhythmias including TdP. However, its incidence is not very common considering the millions of people taking PPIs, but the FDA has advised the physicians to be watchful about this serious adverse effect of PPIs and check the magnesium levels before initiation of PPI treatment.

Frequency, characteristics and nature of risk factors associated with use of QT interval prolonging medications and related drug-drug interactions in a cohort of psychiatry patients

Quite a number of antipsychotic and antidepressant drugs are known to cause significant QT-prolongation. Psychiatric patients constitute a population at notable risk of drug-induced QT-prolongation. The aims were to explore frequency of use of QTc-interval prolonging agents and QT-prolonging drug-drug interactions, and prevalence of risk factors for QTc-interval prolongation in patients reporting to psychiatry out-patient department (OPD) in a tertiary care hospital in India. This prospective cross-sectional study was carried out in the psychiatry OPD at All India Institute of Medical Sciences (AIIMS), Rishikesh, Uttarakhand, India from October 1, 2017 to September 30, 2018 using the relevant prescriptions (i.e., the OPD case record forms and treatment sheets). For each patient, the entire medication list was analyzed for the possibility of interactions, with particular attention on the high-risk QT prolonging ones. Arizona Center for Education and Research on Therapeutics (AZCERT) QT drug lists were used to classify TdP risks of psychotropic and other medications. One thousand three hundred twenty-six (1326) patients attending the psychiatry OPD during the study period were scrutinized. Seven hundred fifty-one 751 patients (56.6%) were males whereas 575 (43.4%) were females in our study. Of the 1326 patients, 636 patients (47.9%) were identified as receiving interacting medications with the ability to induce torsades de pointe (TdP). Nine hundred seventeen (917) interacting medication pairs with torsadogenic risk were encountered. The most frequently interacting medications were from antipsychotic (794), antidepressant (519), antimicrobial (84), proton pump inhibitor (80), anticonvulsant (66), and anti-nausea (25) therapeutic categories. As per AZCERT classification (CredibleMeds TdP risk-stratification lists), 597 (36.8%), 443 (27.3%) and 432 (26.7%) of the interacting medications were associated with known, possible, and conditional risk of TdP, respectively. Concurrent prescriptions of QT-prolonging drugs is frequent in psychiatry OPD setting. Appropriate precautions should be instituted to obviate undesirable outcomes arising out of these interactions. This highlights the pressing need for clear protocols & strategies for implementation to motivate careproviders with clarity in the context of drug use guidelines for rational and safe prescribing in psychiatry.

Machine learning in drug development: Characterizing the effect of 30 drugs on the QT interval using Gaussian process regression, sensitivity analysis, and uncertainty quantification

Prolonged QT intervals are a major risk factor for ventricular arrhythmias and a leading cause of sudden cardiac death. Various drugs are known to trigger QT interval prolongation and increase the proarrhythmic potential. Yet, how precisely the action of drugs on the cellular level translates into QT interval prolongation on the whole organ level remains insufficiently understood. Here we use machine learning techniques to systematically characterize the effect of 30 common drugs on the QT interval. We combine information from high fidelity three-dimensional human heart simulations with low fidelity one-dimensional cable simulations to build a surrogate model for the QT interval using multi-fidelity Gaussian process regression. Once trained and cross-validated, we apply our surrogate model to perform sensitivity analysis and uncertainty quantification. Our sensitivity analysis suggests that compounds that block the rapid delayed rectifier potassium current I Kr have the greatest prolonging effect of the QT interval, and that blocking the L-type calcium current I CaL and late sodium current I NaL shortens the QT interval. Our uncertainty quantification allows us to propagate the experimental variability from individual block-concentration measurements into the QT interval and reveals that QT interval uncertainty is mainly driven by the variability in I Kr block. In a final validation study, we demonstrate an excellent agreement between our predicted QT interval changes and the changes observed in a randomized clinical trial for the drugs dofetilide, quinidine, ranolazine, and verapamil. We anticipate that both the machine learning methods and the results of this study will have great potential in the efficient development of safer drugs.

Rapid transition from methadone to buprenorphine using naltrexone-induced withdrawal: A case report

Background: Patients taking methadone for opioid use disorder may desire transition to buprenorphine for a number of reasons. However, the current recommended approach for this transition generally takes weeks to months as an outpatient, causing considerable discomfort to the patient and a heightened risk of relapse during the transition period. Case: We describe the case of a patient on methadone maintenance who was rapidly transitioned to buprenorphine because of her desire to not return to her methadone clinic. In order to rapidly transition the patient from methadone to buprenorphine, naltrexone was administered to precipitate acute opioid withdrawal, which was followed soon after by buprenorphine induction. Discussion: Rapid transition from methadone maintenance to buprenorphine can be accomplished in inpatients by precipitating acute withdrawal with naltrexone, providing an effective alternative for patients who cannot tolerate the typical protracted methadone taper required prior to buprenorphine induction as an outpatient.

Recurrent Torsades with Refractory QT Prolongation in a 54-Year-Old Man

BACKGROUND QT prolongation is a common, easily overlooked clinical problem with potentially dire consequences. Drug-induced and congenital forms are not mutually exclusive, but are treated differently. Here, we present a case of cryptogenic underlying congenital long QT syndrome (cLQTS) successfully treated with isoproterenol, a drug contraindicated in most congenital forms of this condition. CASE REPORT We present the case of a 54-year-old man who experienced severe QT prolongation after drug administration followed by recurrent episodes of torsade de pointes (TdP) with subsequent ventricular fibrillation (VF) arrest unresponsive to typical therapy. After failing electrolyte repletion, magnesium, amiodarone, and lidocaine, the patient was started on an isoproterenol drip to achieve a heart rate of at least 90 beats per minute (bpm). Isoproterenol resulted in an immediate near-normalization of his QT interval and cessation of his recurrent TdP. The patient was subsequently found to have a mutation of undetermined significance in the KCNQ1 gene, which is implicated in long QT syndrome type 1 (LQT1). Although isoproterenol is contraindicated in LQT1, our patient had an astonishingly therapeutic benefit. CONCLUSIONS After reviewing the electrophysiology of the delayed rectifier potassium current as it relates to long QT syndrome, we propose a mechanism by which our patient's specific mutation may have allowed him to derive benefit from isoproterenol treatment. We believe that there are patients with variants of LQT1 who can be safely treated with isoproterenol.

Pharmacologic Treatment of Opioid Use Disorder: a Review of Pharmacotherapy, Adjuncts, and Toxicity

Opioid use disorder continues to be a significant source of morbidity and mortality in the USA and the world. Pharmacologic treatment with methadone and buprenorphine has been shown to be effective at retaining people in treatment programs, decreasing illicit opioid use, decreasing rates of hepatitis B, and reducing all cause and overdose mortality. Unfortunately, barriers exist in accessing these lifesaving medications: users wishing to start buprenorphine therapy require a waivered provider to prescribe the medication, while some states have no methadone clinics. As such, users looking to wean themselves from opioids or treat their opioid dependence will turn to alternative agents. These agents include using prescription medications, like clonidine or gabapentin, off-label, or over the counter drugs, like loperamide, in supratherapeutic doses. This review provides information on the pharmacology and the toxic effects of pharmacologic agents that are used to treat opioid use disorder. The xenobiotics reviewed in depth include buprenorphine, clonidine, kratom, loperamide, and methadone, with additional information provided on lofexidine, akuamma seeds, kava, and gabapentin.

Late presentation of Torsades de Pointes related to fluoxetine following a multiple drug overdose

Background

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) commonly used in the treatment of depression. While most intoxications with SSRI’s have favorable outcomes and do not require interventions other than strict observation of vital signs and heart rhythm, clinicians should be aware of the life-threatening complications that may occur.

Case presentation

A 61-year-old woman presented to the emergency department after an intentional multiple drug overdose. Upon examination, she was somnolent with stable respiration and hemodynamics. Electrocardiography showed a prolonged QTc interval of 503 ms. The patient was admitted to the ICU for cardiopulmonary monitoring. During admission, the patient remained stable and showed improved neurologic function over time. After 22 h, a second ECG showed normalization of the QTc interval to 458 ms. However, 36 to 40 h after admission, our patient developed recurrent episodes of Torsades de Pointes (TdP) with loss of cardiac output, leading to cardiopulmonary resuscitation. Spontaneous circulation was restored after intravenous administration of magnesium sulphate. Retrospective serum analysis revealed fluoxetine concentrations of 2700 mcg/l.

Conclusion

Most intoxications with selective serotonin reuptake inhibitors (SSRI) have favorable outcomes and do not require medical interventions other than strict cardiopulmonary observation. However, higher doses have been associated with QTc interval prolongation, TdP, serotonin syndrome, and death. This case illustrates that life-threatening complications may occur late in the course of hospital admission. Even though overdoses with SSRI’s generally result in few fatalities, clinicians should be aware of the life-threatening clinical manifestations that may occur. Despite being an imperfect predictor of imminent TdP, continuous monitoring of cardiac rhythm is strongly recommended when either cardiac or non-cardiac symptoms are present.

High prevalence of the risk factors for QT interval prolongation and associated drug-drug interactions in coronary care units

OBJECTIVES

Patients admitted in coronary care units are susceptible to QT interval prolongation due to numerous risk factors. The purpose of this study was to identify the prevalence of risk factors for QT interval prolongation; QT prolonging medications; drug-drug interactions; their predictors; and torsades de pointes risks of drugs.

METHODS

After obtaining approval, this cross-sectional study was carried out during one-year period in coronary care units of two major tertiary care hospitals of Khyber Pakhtunkhwa, Pakistan. The Arizona Center for Education and Research on Therapeutics QT drugs lists and Micromedex DrugReax® were used to identify the QT prolonging medications and QT prolonging drug-drug interactions.

RESULTS

Total 649 patients were included in this study. The most frequent QT prolonging risk factors included use of ≥ 1 QT prolonging drugs (74.9%) and myocardial infarction (61.3%). Total 181 patients were presented with 361 QT prolonging drug-drug interactions. There was significant association of the occurrence of QT prolonging drug-drug interactions with female gender (p = 0.01), 9-10 prescribed medications (p = 0.001), and > 10 prescribed medications (p < 0.001).

CONCLUSIONS

The majority of patients presented with multiple risk factors for QT prolongation in coronary care units which may precipitate lethal outcomes.