Treatment of 150 cases of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments. Final report of a multicenter study

The Bad Reputation of Digoxin in Atrial Fibrillation-Causality or Bias? Nationwide Nested Case-Control Study

Aims

Studies have reported excess risk of mortality associated with digoxin in atrial fibrillation (AF).This study sought to investigate if these findings could be replicated and whether a potential association could be explained by bias.

Methods

Using Danish Nationwide registers, a nested-case control study from 2012 to 2022 was conducted in a cohort of patients with AF. Cases were defined as death of any cause and the exposure was treatment with digoxin compared with beta blockers/verapamil. To investigate bias, additional analyses with negative control outcomes as case definitions-in which we would not expect a plausible association (eg, nursing home admission)-were employed. Associations were reported as hazard ratios (HRs) with 95% confidence intervals (95% CI).

Results

A total of 59,748 cases were identified and matched 1:10 with controls (53% men, median age: 84 [IQR: 77-89]). Digoxin was associated with increased rates of mortality in the entire cohort (HR 1.85, 95% CI 1.78-1.92) as well as subgroups such as patients with heart failure (HR 1.84, 95% CI 1.65-2.06), diabetes (HR 1.85, 95% CI 1.6-2.14), and kidney disease (HR 1.37, 95% CI 1.04-1.8). Significant associations with all negative control outcomes were also found, most notably nursing home admissions (HR 1.79, 95% CI 1.67-1.93).

Conclusion

Digoxin use was associated with increased mortality in AF. However, negative control outcomes were also associated with digoxin use indicating that the described association between digoxin and mortality is likely not causal and being prescribed digoxin is merely a marker of more advanced disease and frailty.

Should digoxin immune fab be administered based solely on reported ingested amount in acute digoxin poisoning?

Acute digoxin poisoning is increasingly uncommon in emergency medicine. Furthermore, controversy exists regarding indications for antidotal digoxin immune fab in acute poisoning. In healthy adults, the fab prescribing information recommends administration based on "known consumption of fatal doses of digoxin: ≥10mg," while many emergency medicine textbooks suggest fab administration be driven by clinical features or potassium concentration. A 54 kg adult, not on digoxin, presented one hour after ingesting 12.5 mg. Electrocardiogram revealed only ST depression and first degree heart block. Initial pulse was 102 beats/min, systolic blood pressure was 170 mmHg. The patient was otherwise asymptomatic. Poison center recommended immediately obtaining serum potassium and digoxin concentrations; call-back was planned for two hours. The emergency physician was instructed to have ≥10 fab vials bedside and to administer if instability ensued. Thirty-five minutes later (≈90 min post-ingestion) ventricular fibrillation cardiac arrest occurred; initial serum potassium resulted at this time at 3.3 mEq/L. Bicarbonate, insulin and glucose, amiodarone, magnesium, calcium, and 10 fab vials were administered. Cardioversion resulted in wide-complex tachycardia which became ventricular fibrillation then asystole and the patient died. Serum digoxin concentration drawn on hospital arrival resulted after death at 44 ng/mL. In this fatal case of acute digoxin poisoning, fab was not empirically recommended because the patient initially did not have significant signs or symptoms that accompanied the history of ingesting ≥10 mg digoxin. While the bedside team was given clear anticipatory guidance by the regional poison center, the patient died despite fab administration once instability occurred.

Expert Consensus on the Diagnosis and Management of Digoxin Toxicity

While there has been a decline in the use of digoxin in patients with heart failure and atrial fibrillation, acute and chronic digoxin toxicity remains a significant clinical problem. Digoxin's narrow therapeutic window and nonspecific signs and symptoms of toxicity create clinical challenges and uncertainty around the diagnostic criteria of toxicity and responsive treatment choices for the bedside clinician. A systematic review of published literature on digoxin toxicity (34,587 publications over 6 decades, with 114 meeting inclusion criteria) was performed to develop 33 consensus statements on diagnostic and therapeutic approaches which were then evaluated through a modified Delphi process involving a panel of experts in cardiology, nursing, emergency medicine, and medical toxicology. The results demonstrate agreement about the need to consider time of ingestion and nature of the exposure (ie, acute, acute-on-chronic, chronic) and the use of digoxin immune Fab for life-threatening exposure to decrease risk of death. While several areas of continued uncertainty were identified, this work offers formalized guidance that may help providers better manage this persistent clinical challenge.

Antidote use for cardiac arrest or hemodynamic instability due to cardiac glycoside poisoning: A narrative review

Introduction

Cardiac glycosides comprise medications such as digoxin and digitoxin, plants, and even certain toad venoms. Intoxication with cardiac glycosides can lead to hemodynamic instability and cardiac arrest. With this narrative review, our objective was to determine if any therapy used in a near-cardiac arrest state due to cardiac glycoside poisoning could improve survival with favourable functional and neurological outcomes.

Methods

We searched the Medline, PubMed, EMBASE and Cochrane Library databases up to February 2022 for controlled trials, observational studies, and case reports. We reviewed studies if participants were exposed to a cardiac glycoside, had hemodynamic instability, and an intervention was attempted to reverse the toxicity. The effect of interventions on (1) survival with favourable functional and neurological outcomes and (2) correction of hemodynamic instability was assessed.

Results

Of the 2422 studies found, 73 were included for analysis, of which 58 were case reports or series, and 15 were observational cohorts. Most patients were intoxicated with medication (60 individual cases and 11 observational cohorts). Administration of digoxin immune-Fab fragments was associated with improved hemodynamic status and survival in medication patients. Administration of magnesium, cardioversion, and cardiac pacing was associated with favourable outcomes, while administration of atropine, antiarrhythmics, or calcium was not.

Conclusion

In patients with hemodynamic instability due to cardiac glycoside intoxication, digoxin immune-Fab fragments should be given, and magnesium administration, cardioversion, and cardiac pacing can reasonably be attempted.

Successful management of massive digoxin overdose using DIGIFab and therapeutic plasma exchange: a case report

BACKGROUND

Despite the efficacy and safety of DIGIFab, it is relatively expensive and has limited availability. In addition, alternative interventions, such as therapeutic plasma exchange, may need to be considered in massive digoxin overdoses. Although few case reports describe its efficacy.

CASE PRESENTATION

We report a case of a 17-year-old white male patient brought by family members to our emergency department in Riyadh, Saudi Arabia. After intentionally ingesting 48 mg of digoxin tablets to commit suicide, the patient's initial digoxin serum level was 8.04 ng/mL. The patient was resuscitated in the emergency department. After admission to the intensive care unit, the patient underwent therapeutic plasma exchange, because of insufficient DIGIFab doses. Afterward, the serum digoxin levels drastically decreased, and his symptoms reverted. The patient was successfully managed and discharged 7 days after admission.

CONCLUSION

Despite insufficient evidence and a limited number of case reports describing the use of extracorporeal treatment in digoxin overdose, we noted the significant impact of therapeutic plasma exchange on our patient. However, therapeutic plasma exchange's use in routine treatment requires stronger evidence to confirm its benefits.

Plasma exchange for the management of digoxin toxicity in an individual with an acute kidney injury: A case report

Digoxin toxicity can be life-threatening. Digoxin-specific antibody (DSA) fragments are used in severe digoxin toxicity, binding to serum-free digoxin and enabling increased renal excretion. In severe renal impairment, clearance of these complexes is prolonged, leading to rebound toxicity. Digoxin and DSA complexes are not dialysable. We present a case of a gentleman with severe digoxin toxicity and acute kidney injury (AKI). Despite receiving DSA doses, his digoxin levels rebounded and symptoms persisted. Based on published case reports, plasma exchange (PEX) after further dosing was arranged. PEX facilitated the removal of digoxin-DSA complexes, bypassing renal excretion. During PEX, clinical signs improved and were sustained. He did not require further dialysis or PEX, renal function recovered and he was discharged. This case highlights challenges in the management of severe digoxin toxicity in patients with a concurrent AKI. The use of PEX enabled digoxin-DSA complex removal and should be considered in these circumstances.

Diagnosis and practical management of digoxin toxicity: a narrative review and consensus

There are currently no universally accepted guidelines for the management of digoxin toxicity. In the absence of clinical practice guidelines, a set of consensus recommendations for management of digoxin toxicity in the clinical setting were developed through a modified Delphi approach. The recommendations highlight the importance of early recognition of signs of potentially life-threatening toxicity that requires immediate treatment with digoxin-specific antibodies. The consensus identifies a straightforward approach to dosing immune antibody fragments according to the presence or absence of signs of life-threatening toxicity. Supportive measures and management of specific signs of toxicity are also covered.

2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

In this focused update, the American Heart Association provides updated guidance for resuscitation of patients with cardiac arrest, respiratory arrest, and refractory shock due to poisoning. Based on structured evidence reviews, guidelines are provided for the treatment of critical poisoning from benzodiazepines, β-adrenergic receptor antagonists (also known as β-blockers), L-type calcium channel antagonists (commonly called calcium channel blockers), cocaine, cyanide, digoxin and related cardiac glycosides, local anesthetics, methemoglobinemia, opioids, organophosphates and carbamates, sodium channel antagonists (also called sodium channel blockers), and sympathomimetics. Recommendations are also provided for the use of venoarterial extracorporeal membrane oxygenation. These guidelines discuss the role of atropine, benzodiazepines, calcium, digoxin-specific immune antibody fragments, electrical pacing, flumazenil, glucagon, hemodialysis, hydroxocobalamin, hyperbaric oxygen, insulin, intravenous lipid emulsion, lidocaine, methylene blue, naloxone, pralidoxime, sodium bicarbonate, sodium nitrite, sodium thiosulfate, vasodilators, and vasopressors for the management of specific critical poisonings.

Development and validation of a risk prediction nomogram for serious arrhythmias in acute digoxin toxicity among pediatrics: A multicenter study

Digoxin is a cardiac glycoside obtained from the leaves of the foxglove plant, Digitalis lanata. Several studies have described the safety of digoxin including various life-threatening events, notably cardiac arrhythmias. Early identification of high-risk patients and subsequent initiation of the utmost medical care are associated with a better prognosis. The assessment of serum digoxin levels, which is not always convenient, is the only tool used to evaluate the severity of digoxin exposure. However, the feasibility of this tool, particularly in resource-restricted countries, remains unclear. Therefore, the current study aimed to establish and validate a feasible alternative tool, a bedside nomogram, to identify pediatric patients diagnosed with acute digoxin intoxication who are at risk of developing serious arrhythmias. This was a two-phase, multicenter, retrospective study. The prevalence of serious arrhythmias was approximately 17%. Patients diagnosed with serious arrhythmias showed significantly higher serum digoxin, random blood glucose, and potassium levels but lower sodium, magnesium, and hemoglobin levels. Serious arrhythmias were associated with significantly lower P-R intervals, shorter QTc intervals, and more frequent digoxin effects (p < 0.05). The proposed nomogram showed that combining age and initial random blood glucose, sodium, and potassium levels could predict the future incidence of serious arrhythmia with an accuracy of 96.2% (sensitivity = 94.4%, specificity = 96.5%), an area under the curve (AUC) of 0.977, and p < 0.001. Validation of the proposed nomogram yielded an AUC for the nomogram probability of approximately 81%, and the AUC for the predicted probability using the developed model was 98.3%, indicating that both the validated model and the developed nomogram were significant predictors of serious arrhythmia. The utility of using the four-factor nomogram to determine the risk of serious arrhythmia in children exposed to an overdose of digoxin is comparable, if not superior, to the serum digoxin level.

Availability of antidotes in Moroccan hospitals: a national survey

AIM

The lack of availability of antidotes is a challenge for hospitals all over the world. The objective of our study was to investigate the availability of antidotes in Moroccan hospitals.

METHODS

A cross-sectional, questionnaire-based study was conducted from November 2018 to April 2019. The questionnaire was sent to 25 hospitals in order to investigate the availability of 42 selected antidotes based on the International Programme on Chemical Safety list.

RESULTS

The survey response rate was 68%. Of the 42 selected antidotes, 38 (90.5%) were available depending on the hospitals included in the study. We found a strong correlation between the availability of antidotes and hospital bed capacity, and logistic regression analysis revealed that bed capacity is the only factor strongly associated with higher antidote stock levels. Some essential antidotes such as digoxin-specific antibody, protamine sulfate, flumazenil and glucagon were unavailable in many of the small- and medium-sized hospitals, and methylene blue, sodium nitroprussiate, Prussian blue and anti-snake venom were absent in all of the hospitals.

CONCLUSION

Despite the great efforts that have been made to improve the availability of antidotes in Morocco, some of these vital products are still lacking in Moroccan hospitals.

Characteristics and Outcomes of Suspected Digoxin Toxicity and Immune Fab Treatment Over the Past Two Decades-2000-2020

The role of digoxin in clinical practice has narrowed over time. Data on digoxin toxicity trends and outcomes are variable and lack granularity for treatment outcomes. This study aimed to address data gaps in digoxin toxicity trends and outcomes in patients treated with or without digoxin immune fab (DIF). This single-center analysis examined patients with signs/symptoms concerning digoxin toxicity, defined as hospital admission or emergency department visit with elevated digoxin serum concentrations (>2 ng/ml) and/or a primary diagnosis code of digoxin toxicity and/or DIF order. Between 2000 and 2020, 727 patients were identified with signs concerning for digoxin toxicity with a mortality rate of 12.7% during admission and 42.7% at 1 year. DIF was ordered in 9% of cases. Incidence of digoxin toxicity per 1,000 patients with a digoxin prescription and frequency of DIF treatment fluctuated over time without a clear trend toward increase or reduction. DIF-treated patients demonstrated a heavier co-morbidity burden and lower presenting heart rates (median 53 [39.5 to 69.5] vs 77 [64.0 to 91.5] beats/min, p <0.001), worse renal function (median estimated glomerular filtration rate, 30.3 [14.8 to 48.6] vs 40.0 [24.2 to 61.2] ml/min/1.73 m², p = 0.013), and higher potassium (median 4.5 [4.0 to 5.3] vs 4.3 [3.9 to 4.8] mEq/L, p = 0.022). Compared with a matched cohort, DIF-treated patients experienced a nonsignificant, numerically lower in-hospital mortality (8.2% vs 15.8%, p = 0.199) and 30-day all-cause hospitalization (14.3% vs 24.7%, p = 0.112) and similar 6-month and 1-year hospitalization and mortality. In conclusion, digoxin toxicity remains a pertinent public health issue despite reduction in digoxin utilization. DIF therapy is used in a medically complex population with a high-acuity illness at presentation and is associated with nonsignificant trends toward reduced in-hospital mortality and early readmission that are attenuated over time.

Life-threatening pediatric poisoning due to ingestion of Bufo bufo toad eggs: A case report

Bufo parotid glands and eggs contain cardiac glycosides also known as bufadienolides. This class of molecules can cause digoxin-like cardiac toxicity, as they can block the sodium potassium-adenosine triphosphatase (Na/K-ATPase) pump. Poisoning with these toxins is rare but carries a high mortality risk. There are only a few cases of toad poisoning that have been reported worldwide, mainly in the southern hemisphere. We will describe the case of a child on the autistic spectrum disorder who developed an acute and severe cardiac bradyarrhythmia soon after being in a mountain creek. The child ingested a large quantity of Bufo bufo toad eggs and developed bradycardia (35/min) associated with junctional rhythm with narrow QRS complexes. The poison control center (PCC) indicated the use of atropine on the way to the nearest hospital and the administration of antidotal therapy, i.e., anti-digoxine fragment antibodies (DigiFab), as soon as possible. The patient was transferred by air ambulance to the Regional Referral Pediatric Hospital (RRPH), tested for digoxin blood level by immuno-essay (0.68 ng/mL) and successfully treated with five vials of DigiFab, since atropine administration produced only a fleeting effect on the cardiac rhythm. Patient was discharged 48 hours after poisoning. The presence of bufadienolides in the toad eggs was also confirmed. To our knowledge, this is the first report of toad egg poisoning in Europe. The administration of Digifab helped to reverse the bufadienolide cardiac toxicity.

Clinical experience with titrating doses of digoxin antibodies in acute digoxin poisoning. (ATOM-6)

INTRODUCTION

For acute digoxin poisoning, it has been recommended to give bolus doses of 10-20 vials or potentially larger than needed doses calculated from dose ingested or the measured concentration. However, a recent revision of internal Poisons Information Centre guidelines prompted a change of our recommendations, specifically instead of large boluses, to use titrating repeated low doses of digoxin antibodies(Digoxin-Fab) based on bedside assessment of cardiac toxicity.

METHODS

This is a prospective observational study of patients with acute digoxin poisoning identified through two Poisons Information Centres and three toxicology units. Patient demographics, signs and symptoms of digoxin toxicity, doses and response to Digoxin-Fab, free and bound serum digoxin concentrations. Outcomes were recorded and analysed.

RESULTS

From September 2013 to September 2020, 23 patients with 25 presentations (median age 56 years, females 56%) were recruited. Median dose ingested was 13 mg(IQR: 9.5-25). Median heart rate (HR) was 41 beats/min before treatment. Initial median digoxin and potassium concentrations were 14.5 nmol/L (IQR: 10.9-20) [11.2 µg/L(IQR: 8.4-15.4)] and 5 mmol/L (IQR: 4.5-5.4 mmol/L), respectively. Gastrointestinal symptoms and acute kidney injury were present in 22 patients (88%) and 5 patients (20%), respectively. Four patients received an initial bolus dose of Digoxin-Fab of 5-20 vials. Twenty-one patients received repeated titrated doses (1-2 vials) of Digoxin-Fab and the median total dose was 4 vials (IQR: 2-7.5). Median maximal change in HR post-Digoxin-Fab was 19 beats/min. The median potassium concentration decrease post-Digoxin-Fab was 0.3 mmol/L. Total dose used in the titration group was 25% and 35% of the predicted doses based on the amount of digoxin ingested or measured serum concentration, respectively. Twelve had free digoxin concentrations measured. Free digoxin concentrations dropped to almost zero after any dose of Digoxin-Fab. Ten patients had a rebound of digoxin >2.6 nmol/L (2 µg/L). There were no deaths from acute digoxin toxicity.

CONCLUSIONS

The new practice of using small, titrated doses of Digoxin-Fab led to a considerable reduction in total usage and major savings. The clinical response to titrated doses was safe and acceptable in acute digoxin poisoning.

Predictive Factors for Recurrence of Serious Arrhythmias in Patients with Acute Digoxin Poisoning

Although digoxin poisoning has declined in the past decades, it still has deleterious outcomes. The hallmark of serious life-threatening arrhythmias remains challenging due to its non-specific initial presentation. Therefore, this study aimed to evaluate the initial predictive factors for recurrent serious arrhythmias and the need for temporary pacing in acute digoxin-poisoned patients. This retrospective cohort study included all patients with acute digoxin poisoning admitted to Tanta University Poison Control Center from 2017 to 2020. Demographic and toxicological data, poisoning severity score (PSS), laboratory investigations, and serial ECG monitoring data were documented. Patients were divided according to their age into a childhood group and adolescence & adulthood group. Each age group was divided into two subgroups according to the presence of recurrent serious arrhythmias. Patient outcomes, including intensive care unit admission, temporary pacing, and in-hospital mortality were recorded. A percentage of 37.34% (n = 31) of the included patients had recurrent serious arrhythmias in both groups. Recurrent serious arrhythmias groups had significantly low heart rate, prolonged PR interval, high PSS, Mobitz II dysrhythmias, elevated serum digoxin, serum potassium and serum creatinine, and increased adverse outcomes compared to other groups. Logistic regression analysis showed that only serum digoxin and potassium levels were significant independent predictors of recurrent serious arrhythmias and temporary pacing. Serum digoxin level had an excellent discriminatory power with the best sensitivity and specificity, followed by serum potassium level in both groups. Thus, monitoring serum digoxin and potassium levels is essential in all patients with acute digoxin poisoning, especially with limited Fab availability.

Causes, Predisposing Factors and Prevention Directions of Drug-induced Bradycardia (Based on the Results of the Hospital Register of Oardiac Medications Overdoses STORM)

Aim. Analysis of drug-induced bradiarrhythmia (DIB) causes and predisposing factors, followed by the development of recommendations for practitioners on its prevention.

Material and methods. The register included consistently all cases of hospitalization at the Regional Vascular Center (Ryazan) due to DIB in 2017 (n=114), 2018 (n=167), and retrospectively in 2014 (n=44). In total, 325 cases were reported: men - 26.1%, age 76.0 [68.0; 82.0] years; patients >65 years - 83.7%, and patients >75 years - 57.9%. The dose of medications with bradycardic action (BCA) taken the day before was known in 227 cases (69.8%), which allowed us to analyze the correctness of the intake regime in these cases.

Results. The excess of a single and / or daily medication dose (absolute overdose, AOD) occurred only in 10.6% of cases and was associated with the patient's attempt to cope with the deterioration of the disease or an acute clinical situation on their own. In other cases, there was no formal violation of the Instructions, but there was an inhibition of the heart's conducting system activity, characteristic of an overdose of medication (the so-called "relative” overdose, ROD). It was due to the summation/potentiation of BCA of several medications or changes in the medication pharmacokinetics. There were no differences in the clinical and demographic characteristics of patients and the provision of medical care in the groups with AOD and ROD (p>0.05). The exception was a high frequency of bradycardia <40 beats / min in AOD group (75.0% vs 49.8%, p=0.019) and, as a result, - management in the conditions of the Intensive Care Unit (66.7% vs 39.9%, p=0.012). Frequency of pre-admission receiving medications in AOD and ROD groups also did not differ (p>0.05): beta-blockers - an average of 64.3%, antiarrhythmic drugs with BCA- 41.0%, cardiac glycosides 25.1% (frequency each of these medicationsin DIB cases over the 5-year period has not changed), an agonist of the 11-imidazoline receptors - moxonidine (12.3%, its frequency has increased 8.9 times in 5 years, p=0.004), non-dihydropyridine calcium antagonists - 7.9% (decrease frequency over 5 years 4.0 times, p=0.002), other - 16.7%. In 56.8% of cases, medications with BCA were used in combination. At admission, a decrease in glomerular filtration rate (GFR) <45 ml/min/1.73 m2 was registered in 56.8% of cases, <30 ml/min/1.73 m2 - in 31.8%, <15 ml/min/1.73 m2 -in 10.9% (differences between groups with p>0.05). Hospital lethality in the AOD group is 4.2%, in the ROD group- 5.4% (p>0.05).

Conclusion. The main reasons of DIB are excess of the recommended dose, unrecorded summation/potentiation of BCA of several medications, and / or changes in the medication pharmacokinetics. Predisposing factors are self-medication of patients with worsening cardiovascular disease or acute clinical situations (e.g., hypertensive crisis), taking multiple medications with BCA, accession of heart disease, manifested by bradyarrhythmia, decrease in GFR, elderly and senile age.

A Visual Resolution of Cardiotoxicity: A Case Report of Digoxin-Induced Bidirectional Ventricular Tachycardia

Digoxin is rarely used in modern cardiovascular disease management. Therefore, digoxin toxicity has been infrequently encountered and it is paramount to diagnose in a timely fashion. Bidirectional ventricular tachycardia is an unusual arrhythmia wherein every other beat has a different QRS axis as it travels alternately down different conduction pathways. The arrhythmia can be a manifestation of myocarditis, myocardial infarct, Andersen-Tawil syndrome, arrhythmogenic right ventricular cardiomyopathy, catecholaminergic polymorphic ventricular tachycardia, herbal aconite poisoning, and digoxin toxicity. This case illustrates the importance of clinician awareness of rare electrocardiogram (EKG) patterns of digoxin toxicity and visual resolution of fatal arrhythmia with timely treatment.

A case of intoxication with tea made from Digitalis purpurea

We present the case of a 34-year-old woman with recurrent depressive disorder who ingested purple foxglove with suicidal intent. She bought a foxglove plant (Digitalis purpurea) over the internet and used all of its leaves to make a tea that she then drank over a period of a few hours. Seventeen hours later, she developed abdominal pain, emesis and bradycardia and was admitted via the emergency department to the intensive care unit for further treatment and monitoring. The plasma digoxin concentration measured 3.53 nmol/l (therapeutic reference range 0.77-1.50 nmol/l) 21 hours after ingestion of the tea. She remained heamodynamically and neurologically stable, was treated with antiemetics and simple analgesia and did not require digoxin-specific antibodies. Despite normal renal function, her plasma digoxin half-life was prolonged (estimated 76 h), reflecting the long half-life of the parent compound digitoxin which is the main cardiac glycoside in Digitalis purpurea. She was transferred to psychiatric care 48 h after admission. In this report, we compare this case to other similar cases, which to date have only been rarely reported in the literature.

Detecting Digoxin Toxicity by Artificial Intelligence-Assisted Electrocardiography

Although digoxin is important in heart rate control, the utilization of digoxin is declining due to its narrow therapeutic window. Misdiagnosis or delayed diagnosis of digoxin toxicity is common due to the lack of awareness and the time-consuming laboratory work that is involved. Electrocardiography (ECG) may be able to detect potential digoxin toxicity based on characteristic presentations. Our study attempted to develop a deep learning model to detect digoxin toxicity based on ECG manifestations. This study included 61 ECGs from patients with digoxin toxicity and 177,066 ECGs from patients in the emergency room from November 2011 to February 2019. The deep learning algorithm was trained using approximately 80% of ECGs. The other 20% of ECGs were used to validate the performance of the Artificial Intelligence (AI) system and to conduct a human-machine competition. Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were used to evaluate the performance of ECG interpretation between humans and our deep learning system. The AUCs of our deep learning system for identifying digoxin toxicity were 0.912 and 0.929 in the validation cohort and the human-machine competition, respectively, which reached 84.6% of sensitivity and 94.6% of specificity. Interestingly, the deep learning system using only lead I (AUC = 0.960) was not worse than using complete 12 leads (0.912). Stratified analysis showed that our deep learning system was more applicable to patients with heart failure (HF) and without atrial fibrillation (AF) than those without HF and with AF. Our ECG-based deep learning system provides a high-accuracy, economical, rapid, and accessible way to detect digoxin toxicity, which can be applied as a promising decision supportive system for diagnosing digoxin toxicity in clinical practice.

Adverse Events Associated with Use of Digoxin Immune Fab Reported to the US Food and Drug Administration Adverse Event Reporting System, 1986-2019

Background

Digoxin immune fab products, DigiBind and DigiFab, are antidotes for the treatment of patients with life-threatening or potentially life-threatening digoxin toxicity or overdose. Although approved by the US Food and Drug Administration (FDA) in 1986 (DigiBind) and 2001 (DigiFab), there remains a paucity of literature describing the safety of these products in the postmarketing setting.

Objective

We sought to assess US adverse event (AE) reports submitted to the FDA Adverse Event Reporting System (FAERS) for DigiBind and DigiFab in the postmarketing period.

Patients and Methods

We searched reports for DigiBind and DigiFab submitted from the time of each product approval through December 31, 2019. Descriptive statistics were used to assess AE reports for DigiBind and DigiFab. Empirical Bayes geometric means (EBGMs) and their 90% confidence intervals were computed to identify disproportionate (i.e., at least twice the expected) reporting of DigiBind and DigiFab. Reports describing selected AEs and death outcomes were individually reviewed.

Results

A total of 78 DigiBind and 43 DigiFab reports were identified, of which 68 DigiBind (87.2%) and 27 DigiFab (62.8%) reports were serious. Among the most frequently reported AEs for both products [DigiBind, DigiFab, respectively] were cardiac (bradycardia [3.8%, 3.9%], cardiac arrest [3.3%, 3.9%], and hypotension [2.4%, 2.6%]) and non-cardiac (nausea [1.9%, 2.6%] and hyperkalemia [1.4%, 1.9%]) events. These AEs were labeled events or confounded by indication for use (digoxin toxicity). Nineteen (24.4%) DigiBind and 13 (30.2%) DigiFab reports described an outcome of death, of which seven (53.8%) DigiFab reports were attributed to poisoning with non-digoxin cardiac glycosides. No deaths could be attributed to DigiBind or DigiFab administration.

Conclusions

Our analysis did not identify new safety concerns for DigiBind or DigiFab. Most AEs reported were labeled events or confounded by indication for use.

Dromedary camels as a natural source of neutralizing nanobodies against SARS-CoV-2

The development of prophylactic and therapeutic agents for coronavirus disease 2019 (COVID-19) is a current global health priority. Here, we investigated the presence of cross-neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in dromedary camels that were Middle East respiratory syndrome coronavirus (MERS-CoV) seropositive but MERS-CoV free. The tested 229 dromedaries had anti–MERS-CoV camel antibodies with variable cross-reactivity patterns against SARS-CoV-2 proteins, including the S trimer and M, N, and E proteins. Using SARS-CoV-2 competitive immunofluorescence immunoassays and pseudovirus neutralization assays, we found medium-to-high titers of cross-neutralizing antibodies against SARS-CoV-2 in these animals. Through linear B cell epitope mapping using phage immunoprecipitation sequencing and a SARS-CoV-2 peptide/proteome microarray, we identified a large repertoire of Betacoronavirus cross-reactive antibody specificities in these dromedaries and demonstrated that the SARS-CoV-2–specific VHH antibody repertoire is qualitatively diverse. This analysis revealed not only several SARS-CoV-2 epitopes that are highly immunogenic in humans, including a neutralizing epitope, but also epitopes exclusively targeted by camel antibodies. The identified SARS-CoV-2 cross-neutralizing camel antibodies are not proposed as a potential treatment for COVID-19. Rather, their presence in nonimmunized camels supports the development of SARS-CoV-2 hyperimmune camels, which could be a prominent source of therapeutic agents for the prevention and treatment of COVID-19.

Management of pharmaceutical and recreational drug poisoning

BACKGROUND

Poisoning is one of the leading causes of admission to the emergency department and intensive care unit. A large number of epidemiological changes have occurred over the last years such as the exponential growth of new synthetic psychoactive substances. Major progress has also been made in analytical screening and assays, enabling the clinicians to rapidly obtain a definite diagnosis.

METHODS

A committee composed of 30 experts from five scientific societies, the Société de Réanimation de Langue Française (SRLF), the Société Française de Médecine d'Urgence (SFMU), the Société de Toxicologie Clinique (STC), the Société Française de Toxicologie Analytique (SFTA) and the Groupe Francophone de Réanimation et d'Urgences Pédiatriques (GFRUP) evaluated eight fields: (1) severity assessment and initial triage; (2) diagnostic approach and role of toxicological analyses; (3) supportive care; (4) decontamination; (5) elimination enhancement; (6) place of antidotes; (7) specificities related to recreational drug poisoning; and (8) characteristics of cardiotoxicant poisoning. Population, Intervention, Comparison, and Outcome (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. Analysis of the literature and formulation of recommendations were then conducted according to the GRADE® methodology.

RESULTS

The SRLF-SFMU guideline panel provided 41 statements concerning the management of pharmaceutical and recreational drug poisoning. Ethanol and chemical poisoning were excluded from the scope of these recommendations. After two rounds of discussion and various amendments, a strong consensus was reached for all recommendations. Six of these recommendations had a high level of evidence (GRADE 1±) and six had a low level of evidence (GRADE 2±). Twenty-nine recommendations were in the form of expert opinion recommendations due to the low evidences in the literature.

CONCLUSIONS

The experts reached a substantial consensus for several strong recommendations for optimal management of pharmaceutical and recreational drug poisoning, mainly regarding the conditions and effectiveness of naloxone and N-acetylcystein as antidotes to treat opioid and acetaminophen poisoning, respectively.

Bibliometric profile of global scientific research on digoxin toxicity (1849-2015)

Digoxin is a cardiac glycoside derived from the common foxglove digitalis purpurea and has been available for several centuries as a medicinal agent. Despite extensive patient experience over many years, there remains some controversy regarding the possibility that digoxin might have a deleterious effect on survival. This study was constructed to assess trends in digoxin toxicity research using well-established qualitative and quantitative bibliometric indicators. The current study is based on publications that have been indexed in Scopus. Articles referring to the subject of digoxin toxicity between 1849 and 2015 were assessed according to the document type, publication language, countries/territories, institutions, journal, impact factors, total number of citations, h-index, average number of citations per publication, and international collaborations. There were 2900 publications that included 2542 (87.7%) original research articles, while 5.3% were reviews and 4.6% letters. The country of origin was the USA in 849 publications, Germany in 241, the UK in 150, and France in 143. The USA and the UK had the highest number of international collaborations. The average number of citations per publications related to digoxin toxicity was 8.1, and the h-index was 59. The USA and Canada had the highest h-indices by country at 46 and 22, respectively. This study presents the first bibliometric analysis on digoxin toxicity publications. The USA was the most important contributors to digoxin toxicity literature with the greatest international collaboration, largest number of articles and highest h-index, followed by Germany and the UK. There has been a trend towards reduced publication numbers related to digoxin toxicity at global level, although it is still an important issue and we present the current research themes related to digoxin toxicity that were identified.

Digoxin: Pharmacology and toxicology-A review

Digoxin is a cardiac glycoside used as drug in case of heart problems, including congestive heart failure, atrial fibrillation or flutter, and certain cardiac arrhythmias. It has a very narrow therapeutic window of the medication. Digoxin is toxic substance with well known cardiotoxic effect. In this work, pharmacology and toxicology of digoxin are summarized; Its pharmacokinetics, pharmacodynamics, available acute toxicity data (different species, different administration routes) are summarized in this article. Moreover, its treatment side effect and human poisonings are thoroughly discussed. Finally, appropriate therapy regimen is proposed.

Digoxin-specific Fab and therapeutic plasma exchange for digitalis intoxication and renal failure

Treatment of chronic digitalis intoxication includes suspension of drug intake, which may be sufficient in case of mild manifestations, and supportive measures. Severe bradycardia requires the administration of atropine or isoproterenol; placement of a temporary pacemaker may be required in case of absent response to pharmacological therapy. Severe and life-threatening manifestations should be treated with digoxin-specific fragment antigen binding antibodies (Fab). Therapeutic plasma exchange has been suggested, in addition to Fab therapy, to maximize the clearance of Fab-digoxin complexes in patients with renal failure. To date, few case reports have described the use of such a therapeutic approach; currently, extracorporeal methods are not recommended as part of the treatment of digitalis intoxication, and stronger evidence is required to establish their benefit.

[Recognizing rare cardiac diseases by electrocardiogram]

A number of rare cardiac diseases can be recognized by electrocardiogram (ECG). This article illustrates the clinical importance of ECG as a key diagnostic tool to detect Wolff-Parkinson-White syndrome and channelopathies, which are frequently diagnosed late after one or more affected family members have become victims of sudden cardiac death. These channelopathies include long QT syndrome, short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. In addition, typical ECG findings are frequently present in patients with idiopathic ventricular tachycardia, arrhythmogenic right ventricular dysplasia, digitalis intoxication, hyperkalemia, acute cor pulmonale due to pulmonary embolism, as well as severe left ventricular hypertrophy as in hypertrophic cardiomyopathy.

Life-threatening digoxin toxicity due to drug-drug interactions in an HIV-positive man

Drug-drug interactions with corticosteroids, causing Cushing's syndrome with secondary adrenal suppression, are well known in HIV patients. Corticosteroids are widely prescribed in the HIV-positive population. However, digoxin is rarely used in HIV patients; hence, digoxin toxicity due to drug-drug interaction is not widely recognised. Nevertheless, this practice might change in the future as HIV cohorts of patients are ageing, due to the successful treatment of HIV infection with combination antiretroviral therapy. We report a case of digoxin toxicity in an HIV-positive 51-year-old man, due to a combination of drug-drug interaction and renal impairment. The first case report of digoxin toxicity due to drug-drug interaction with ritonavir in an HIV-positive woman was published in 2003. To the best of our knowledge, no similar case report has since been published in the literature. This case alerts the profession to the importance of drug-drug interaction and highlights the clinical features of digoxin toxicity.

Digoxin: The Monarch of Cardiac Toxicities

The cardiac steroids (or glycosides) are a heterogeneous group of compounds that have been well recognized for both their clinical benefit and inherent toxicity. This review will primarily focus on digoxin because of its widespread clinical use, although the other cardiac steroids will be discussed in less detail. The cardiac steroids have a narrow therapeutic index and remain a significant source of toxicity, with nearly 5000 human exposures reported to the American Association of Poison Control Centers in 2002. Digoxin reversibly binds to the α subunit of the Na+ -K+ ATPase pump and completely inhibits its enzymatic and transport functions. The cumulative effect on cardiac tissue is dependent on the number of Na+ -K+ ATPase pump sites that are occupied by cardiac steroid molecules. It is important to recall the pharmacokinetics of digoxin in that serum digoxin levels drawn prior to tissue distribution (<6 hours) do not accurately reflect acute toxicity. Signs and symptoms of toxicity vary between acute and chronic intoxications. A systematic approach guided by clinical symptoms with early administration of immunotherapy can lead to a significant reduction of morbidity and mortality in digoxin-poisoned patients.

Antidote Use in the Critically Ill Poisoned Patient

The proper use of antidotes in the intensive care setting when combined with appropriate general supportive care may reduce the morbidity and mortality associated with severe poisonings. The more commonly used antidotes that may be encountered in the intensive care unit ( N-acetylcysteine, ethanol, fomepizole, physostigmine, naloxone, flumazenil, sodium bicarbonate, octreotide, pyridoxine, cyanide antidote kit, pralidoxime, atropine, digoxin immune Fab, glucagon, calcium gluconate and chloride, deferoxamine, phytonadione, botulism antitoxin, methylene blue, and Crotaline snake antivenom) are reviewed. Proper indications for their use and knowledge of the possible adverse effects accompanying antidotal therapy will allow the physician to appropriately manage the severely poisoned patient.