Determining the Risk of Elevated Digoxin Concentrations Following Loading Dose in Patients With Acute and Chronic Kidney Disease.

BACKGROUND: The optimal loading dose of digoxin in patients with reduced kidney function is unknown. Tertiary references recommend reduced loading doses; however, these recommendations are based on immunoassays that are falsely elevated by the presence of digoxin-like immunoreactive substances, a problem that is minimized in modern assays. OBJECTIVE: To determine whether chronic kidney disease (CKD) or acute kidney injury (AKI) is associated with supratherapeutic digoxin concentrations after a digoxin loading dose. METHODS: A retrospective analysis on patients who received an intravenous loading dose of digoxin with a digoxin concentration collected 6 to 24 hours after the end of the dose. Patients were stratified into 3 groups: AKI, CKD, and non-AKI/CKD (NKI) based on glomerular filtration rate and serum creatinine. The primary outcome was frequency of supratherapeutic digoxin concentrations (>2 ng/mL) and secondary outcomes included frequency of adverse events. RESULTS: A total of 146 digoxin concentrations were included (AKI = 59, CKD = 16, NKI = 71). Frequencies of supratherapeutic concentrations were similar between groups (AKI: 10.2%, CKD: 18.8%, NKI: 11.3%; P = 0.61). Pre-planned logistic regression demonstrated no significant relationship between kidney function group and the development of a supratherapeutic concentration (AKI: odds ratio [OR]: 1.3, 95% confidence interval [CI]: 0.4-4.5; CKD: OR 4.3, 95% CI: 0.7-23). CONCLUSION AND RELEVANCE: This is the first study in routine clinical practice evaluating the relationship between kidney function and digoxin peak concentrations that differentiates AKI from CKD. We did not find a relationship between kidney function and peak concentrations; however, the group with CKD was underpowered.

Evaluation of Safety and Efficacy of Intravenous Digoxin Loading Doses Based on Ideal Body Weight.

BACKGROUND: Intravenous digoxin loading dose recommendations differ between clinical guidelines and Food and Drug Administration packaging for acute rate control. OBJECTIVE: The objective of this study was to assess the safety and efficacy of intravenous digoxin loading in patients who received ≤12 µg/kg and >12 µg/kg of digoxin using ideal body weight (IBW). METHODS: This single center retrospective cohort study with exempt status from the local Institutional Review Board included patients who received intravenous digoxin and had a serum digoxin concentration (SDC) drawn. Digoxin doses >36 hours after the first dose were excluded. Patients who received a total of >12 µg/kg and ≤12 µg/kg IBW were compared. The primary endpoint was frequency of SDCs ≥1.2 ng/mL, which have been shown to be associated with increased mortality. RESULTS: A total of 244 patients were included (144 receiving >12 µg/kg and 100 receiving ≤12 µg/kg). There were significantly more SDC ≥1.2 ng/mL in the >12 µg/kg group than the ≤12 µg/kg group (50.6% vs. 30.0%; adjusted odds ratio, 3.19; 95% confidence interval [CI]: 1.79-5.84), with no difference in rate control failure. Major limitations of the study include retrospective nature and possible selection bias. CONCLUSION AND RELEVANCE: Compared to patients who received digoxin doses ≤12 µg/kg IBW, patients who received >12 µg/kg IBW had higher rates of SDC ≥1.2 ng/mL. This suggests that appropriate weight-based dosing with 8 to 12 µg/kg IBW has the potential to be a safer approach to digoxin loading, rather than frequently used dosing strategies that result in doses >12 µg/kg.

Closing the Digitalis Divide: Back to the Basics of Randomized Controlled Trials.

PURPOSE: Publishe d decades after several randomized controlled trials (RCT) demonstrating decreased hospitalizations and no effect on all-cause mortality with digoxin use, a series of meta-analyses linking digoxin treatment and mortality have contributed to a narrower application of this medication for the management of heart failure (HF) and atrial fibrillation (AF). Given the conflicting data from the earlier RCTs and more recent meta-analyses, there is a growing polarization among providers for and against the use of digoxin in managing these conditions. METHODS: To help close this divide, we provide a perspective on the literature with special attention to the quality of both older and more recent studies on this subject. RESULTS: The data from the highest quality studies we have, RCTs, suggest that digoxin use in patients with HF and/or AF is associated with improvement in several areas of outcomes including functional capacity, symptom management, reduced hospitalizations, fewer deaths due to HF, and treatment of refractory chronic heart failure with rEF, and may even have overall mortality benefit when serum digoxin concentrations are within therapeutic range. These effects are more pronounced in patients with EF < 25% and NYHA Class II-IV and at highest risk for hospitalization. CONCLUSION: As the risk of confounding factors was minimized by the study design, the likelihood that positive outcomes were identified with digoxin use increased. Clinicians and researchers need further adequately designed and powered RCTs exploring the connection between digoxin therapy and mortality, hospitalizations, and symptom management.

Effect of digoxin on all-cause and cardiovascular mortality in patients with atrial fibrillation with and without heart failure: an umbrella review of systematic reviews and 12 meta-analyses.

PURPOSE: To perform a systematic umbrella review with meta-analysis to evaluate the certainty of evidence on mortality risk associated with digoxin use in patients with atrial fibrillation (AF) with or without heart failure (HF). METHODS: We systematically searched MEDLINE, Embase, and Web of Science databases from inception to 19 October 2021. We included systematic reviews and meta-analyses of observational studies investigating digoxin effects on mortality of adult patients with AF and/or HF. The primary outcome was all-cause mortality; secondary outcome was cardiovascular mortality. Certainty of evidence was evaluated by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool and the quality of systematic reviews/meta-analyses by the A MeaSurement Tool to Assess systematic Reviews 2 (AMSTAR2) tool. RESULTS: Eleven studies accounting for 12 meta-analyses were included with a total of 4,586,515 patients. AMSTAR2 analysis showed a high quality in 1, moderate in 5, low in 2, and critically low in 3 studies. Digoxin was associated with an increased all-cause mortality (hazard ratio [HR] 1.19, 95% confidence interval [95%CI] 1.14-1.25) with moderate certainty of evidence and with an increased cardiovascular mortality (HR 1.19, 95%CI 1.06-1.33) with moderate certainty of evidence. Subgroup analysis showed that digoxin was associated with all-cause mortality both in patients with AF alone (HR 1.23, 95%CI 1.19-1.28) and in those with AF and HF (HR 1.14, 95%CI 1.12-1.16). CONCLUSION: Data from this umbrella review suggests that digoxin use is associated with a moderate increased risk of all-cause and cardiovascular mortality in AF patients regardless of the presence of HF. TRIAL REGISTRATION: This review was registered in PROSPERO (CRD42022325321).

Fundus autofluorescence, optical coherence tomography and electroretinography abnormalities in a patient with digoxin retinopathy that resemble those in KCNV2-associated retinopathy.

BACKGROUND: Digoxin related retinal toxicity causes blurred vision, photophobia, central scotoma, color vision abnormality, and electroretinography (ERG) abnormalities. Here, we report a case with transient abnormalities in vison, in which fundus autofluorescence (FAF), optical coherence tomography (OCT), and ERG findings resembled those in KCNV2 (potassium voltage-gated channel modifier subfamily V member 2)-associated retinopathy. CASE REPORT: An 89-year-old woman presented with complaints of acute blurred vision, nyctalopia, photophobia, and color vision abnormality. She received digoxin for tachycardia induced by atrial fibrillation for a month. The fundi showed a faint white ring at the fovea, which showed hyperfluorescence in FAF. OCT showed a thickened EZ in the macula. A dark-adapted (DA)-30 ERG showed a reduced and "squaring (trough-flattened)" a-wave, and a delayed, supernormal b-wave, resulting in a high b/a-wave amplitude ratio. The digoxin dose was reduced following an elevation in serum levels. Five weeks later, her visual acuities improved, and abnormal hyperfluorescence on FAF disappeared. After 6 months, no visual symptoms were reported. The ellipsoid-zone thickening in OCT improved; however, the b/a-wave amplitude ratio on DA-30 ERG remained high. The b-wave in LA-long-flash ERG was initially reduced, which improved after correction of serum level of digoxin. CONCLUSIONS: The patient's clinical findings resembled those of patients with KCNV2-associated retinopathy or temporal hyperkalemia. These disorders appear to have a common pathogenesis, which may be related to abnormal extracellular potassium levels in the retina. The on-bipolar cells seemed to be more affected than the off-bipolar cells in digoxin related retinal toxicity.

Machine Learning-Based Prediction of Digoxin Toxicity in Heart Failure: A Multicenter Retrospective Study.

Digoxin toxicity (plasma digoxin concentration ≥0.9 ng/mL) is associated with worsening heart failure (HF). Decision tree (DT) analysis, a machine learning method, has a flowchart-like model where users can easily predict the risk of adverse drug reactions. The present study aimed to construct a flowchart using DT analysis that can be used by medical staff to predict digoxin toxicity. We conducted a multicenter retrospective study involving 333 adult patients with HF who received oral digoxin treatment. In this study, we employed a chi-squared automatic interaction detection algorithm to construct DT models. The dependent variable was set as the plasma digoxin concentration (≥ 0.9 ng/mL) in the trough during the steady state, and factors with p < 0.2 in the univariate analysis were set as the explanatory variables. Multivariate logistic regression analysis was conducted to validate the DT model. The accuracy and misclassification rates of the model were evaluated. In the DT analysis, patients with creatinine clearance <32 mL/min, daily digoxin dose ≥1.6 µg/kg, and left ventricular ejection fraction ≥50% showed a high incidence of digoxin toxicity (91.8%; 45/49). Multivariate logistic regression analysis revealed that creatinine clearance <32 mL/min and daily digoxin dose ≥1.6 µg/kg were independent risk factors. The accuracy and misclassification rates of the DT model were 88.2 and 46.2 ± 2.7%, respectively. Although the flowchart created in this study needs further validation, it is straightforward and potentially useful for medical staff in determining the initial dose of digoxin in patients with HF.

Repurposing the cardiac glycoside digoxin to stimulate myelin regeneration in chemically-induced and immune-mediated mouse models of multiple sclerosis.

Multiple sclerosis (MS) is a central nervous system (CNS) autoimmune disease characterized by inflammation, demyelination, and neurodegeneration. The ideal MS therapy would both specifically inhibit the underlying autoimmune response and promote repair/regeneration of myelin as well as maintenance of axonal integrity. Currently approved MS therapies consist of non-specific immunosuppressive molecules/antibodies which block activation or CNS homing of autoreactive T cells, but there are no approved therapies for stimulation of remyelination nor maintenance of axonal integrity. In an effort to repurpose an FDA-approved medication for myelin repair, we chose to examine the effectiveness of digoxin, a cardiac glycoside (Na+ /K+ ATPase inhibitor), originally identified as pro-myelinating in an in vitro screen. We found that digoxin regulated multiple genes in oligodendrocyte progenitor cells (OPCs) essential for oligodendrocyte (OL) differentiation in vitro, promoted OL differentiation both in vitro and in vivo in female naïve C57BL/6J (B6) mice, and stimulated recovery of myelinated axons in B6 mice following demyelination in the corpus callosum induced by cuprizone and spinal cord demyelination induced by lysophosphatidylcholine (LPC), respectively. More relevant to treatment of MS, we show that digoxin treatment of mice with established MOG35-55 -induced Th1/Th17-mediated chronic EAE combined with tolerance induced by the i.v. infusion of biodegradable poly(lactide-co-glycolide) nanoparticles coupled with MOG35-55 (PLG-MOG35-55 ) completely ameliorated clinical disease symptoms and stimulated recovery of OL lineage cell numbers. These findings provide critical pre-clinical evidence supporting future clinical trials of myelin-specific tolerance with myelin repair/regeneration drugs, such as digoxin, in MS patients.

A NOS1AP gene variant is associated with a paradoxical increase of the QT-interval shortening effect of digoxin.

Digoxin is characterized by a small therapeutic window and a QT-interval shortening effect. Moreover, it has been shown that the genetic variants of the nitric oxide synthase-1 adaptor protein (NOS1AP) gene are associated with QT-interval prolongation. We investigated whether the rs10494366 variant of the NOS1AP gene decreases the QT-interval shortening effect of digoxin in patients using this drug. We included 10,057 individuals from the prospective population-based cohort of the Rotterdam Study during a median of 12.2 (interquartile range (IQR) 6.7-18.1) years of follow-up. At study entry, the mean age was 64 years and almost 59% of participants were women. A total of 23,179 ECGs were longitudinally recorded, of which 334 ECGs were from 249 individuals on digoxin therapy. The linear mixed model analysis was used to estimate the effect of the rs10494366 variant on the association between digoxin use and QT-interval duration, adjusted for age, sex, RR interval, diabetes, heart failure, and history of myocardial infarction. In non-users of digoxin, the GG genotype was associated with a significant 6.5 ms [95% confidence interval (CI) 5.5; 7.5] longer QT-interval duration than the TT variant. In current digoxin users, however, the GG variant was associated with a significantly -23.9 [95%CI -29.5; -18.5] ms shorter mean QT-interval duration than in those with the TT variant with -15.9 [95%CI -18.7; -13.1]. This reduction was strongest in the high digoxin dose category [≥0.250 mg/day] with the GG genotype group, with -40.8 [95%CI -52.5; -29.2] ms changes compared to non-users. Our study suggests that the minor homozygous GG genotype group of the NOS1AP gene rs10494366 variant is associated with a paradoxical increase of the QT-interval shortening effect of digoxin in a population of European ancestry.

Digoxin in Patients With Advanced Heart Failure and Sinus Rhythm Submitted to Cardiac Resynchronization Therapy-Is There Any Benefit?

ABSTRACT: Digoxin (DG) use in patients with heart failure with reduced ejection fraction (HFrEF) and sinus rhythm remains controversial. We aimed to assess the prognostic effect of DG in patients in sinus rhythm submitted to cardiac resynchronization therapy (CRT). Retrospective study including 297 consecutive patients in sinus rhythm, with advanced HFrEF submitted to CRT. Patients were divided into 2 groups: with DG and without DG (NDG). During a mean follow-up of 4.9 ± 3.4 years, we evaluated the effect of DG on the composite end point defined as cardiovascular hospitalization, progression to heart transplantation, and all-cause mortality. Previous to CRT, 104 patients (35%) chronically underwent DG and 193 patients (65%) underwent NDG treatment. The 2 groups did not differ significantly regarding HF functional class, HF etiology, QRS, and baseline left ventricular ejection fraction. The proportion of responders to CRT was similar in both groups (54% in DG vs. 56% in NDG; P = 0.78). During the long-term follow-up period, the primary end point occurred in a higher proportion in DG patients (67 vs. 48%; P = 0.002). After adjustment for potential confounders, DG use remained as an independent predictor of the composite end point of CV hospitalization, heart transplantation, and all-cause mortality [hazards ratio = 1.58; confidence interval, 95 (1.01-2.46); P = 0.045]. In conclusion, in patients in sinus rhythm with HFrEF submitted to CRT, DG use was associated with CV hospitalization, progression to heart transplant, and all-cause mortality.

Digoxin use and clinical outcomes in elderly Chinese patients with atrial fibrillation: a report from the Optimal Thromboprophylaxis in Elderly Chinese Patients with Atrial Fibrillation (ChiOTEAF) registry.

AIMS: Prior studies have reported conflicting results on digoxin's impact on clinical outcomes and quality of life, and there are limited data from Asia. The aim of this study is to evaluate the use of digoxin and its impact on clinical outcomes and quality of life in a high-risk cohort of elderly Chinese atrial fibrillation (AF) patients. METHODS AND RESULTS: The Optimal Thromboprophylaxis in Elderly Chinese Patients with Atrial Fibrillation (ChiOTEAF) registry is a prospective, multicentre nationwide study conducted from October 2014 to December 2018. Endpoints of interest were the composite outcome of all-cause death/any thromboembolism (TE), all-cause death, cardiovascular death, sudden cardiac death, and TE events, as well as the quality of life. The eligible cohort for this analysis included 6391 individuals, of whom 751 (11.8%) patients were treated with digoxin. On multivariate analysis, the use of digoxin was associated with a higher odds ratio (OR) of composite outcome [OR: 1.71; 95% confidence interval (CI): 1.32-2.22], all-cause death (OR: 1.62; 95% CI: 1.23-2.14), and any TE (OR: 1.78; 95% CI: 1.08-2.95). Results were consistent in a subgroup of patients with diagnosed heart failure (HF) and patients with permanent AF. The use of digoxin was associated with worse health-related quality of life (mean EQ index: 0.76 ± 0.19 vs. 0.84 ± 0.18; P < 0.001). CONCLUSIONS: In this nationwide cohort study, digoxin use was associated with an overall higher risk of the composite outcome of all-cause death/any TE, all-cause death, and any TE, regardless of HF diagnosis. Patients treated with digoxin had a worse health-related quality of life.

Association Between Digoxin Use and Cardiac Function in Infants With Single-Ventricle Congenital Heart Disease During the Interstage Period.

OBJECTIVES: To examine the association between digoxin use and cardiac function assessed by echocardiographic indices in infants with single-ventricle (SV) congenital heart disease (CHD) during the interstage period. DESIGN: Retrospective cohort study. SETTING: Fifteen North American hospitals. PATIENTS: Infants discharged home following stage 1 palliation (S1P) and prior to stage 2 palliation (S2P). Infants with no post-S1P and pre-S2P echocardiograms were excluded. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 373 eligible infants who met inclusion criteria, 140 (37.5%) were discharged home on digoxin. In multivariable linear and logistic regressions, we found that compared with infants discharged home without digoxin, those discharged with digoxin had a smaller increase in end-systolic volume (ß = -8.17 [95% CI, -15.59 to -0.74]; p = 0.03) and area (ß = -1.27 [-2.45 to -0.09]; p = 0.04), as well as a smaller decrease in ejection fraction (ß = 3.38 [0.47-6.29]; p = 0.02) and fractional area change (ß = 2.27 [0.14-4.41]; p = 0.04) during the interstage period. CONCLUSIONS: Digoxin may partially mitigate the expected decrease in cardiac function during the interstage period through its positive inotropic effects. Prospective clinical trials are needed to establish the pharmacokinetics, safety, and efficacy of digoxin use in SV CHD.

Repurposing of digoxin in pain and inflammation: An evidence-based study.

In recent years, the drug repositioning strategy has gained considerable attention in the drug discovery process that involves establishing new therapeutic uses of already known drugs. In line with this, we have identified digoxin a cardiac glycoside, as a potent inhibitor of soluble epoxide hydrolase (sEH) enzyme employing in silico high throughput screening protocols and further confirmed using in vitro cell-free sEH inhibitory assay and in vivo preclinical studies in rodents for its repurposing in hyperalgesia, inflammation, and related disorders. Oral administration of digoxin at dose 0.2 mg/kg significantly reduced (p < .0001) the allodynia in mice induced by using hot plate (3.6 ± 1.9) and tail-flick test (7.58 ± 0.9). In addition, digoxin at a dose of 0.2 mg/kg showed marked reduction (94%, p < .0001) in acetic acid-induced abdominal contraction in rats. Further, digoxin also demonstrated antipyretic activity (37.04 ± 0.2, p < .0001) and showed notable reduction (0.60 ± 0.06) in carrageenan-induced paw edema in rats. Also, the histopathological evaluation revealed that digoxin treatment attenuated the edema, neutrophil infiltration, and alveolar septal thickening in lung tissue. These findings are novel and highlight the newer insights towards repurposing digoxin as a new lead in the treatment of hyperalgesia, inflammation, and related disorders.

Development of an experimental model for ocular toxicity screening in Zebrafish.

BACKGROUND: To investigate the efficacy of a novel experimental model for exploring visual function using a contrast-optomotor response (C-OMR) assay made by applying the contrast sensitivity test to the OMR assay in zebrafish. METHODS: Zebrafish larvae were treated with 0 (control), 5, 10, or 15 µM gentamicin and digoxin for 24 h at four days post-fertilization (dpf). Zebrafish larvae were assessed using the C-OMR assay with graded contrast gray-white stripes at 5 dpf, and the results were expressed as the percentage of larvae that finished swimming for 30 s (n = 20 per each group). The same C-OMR assay was repeated four times using different larvae. RESULTS: The percentage of larvae that finished swimming within 30 s was significantly reduced in larvae treated with 5, 10, and 15 µM gentamicin and 10 and 15 µM digoxin as compared to the Control groups. The C-OMR assay could distinguish that the decrease in visual function was different depending on the concentration of gentamicin and digoxin (5, 10, and 15 µM), whereas the OMR test with one contrast gray-white stripe could not. CONCLUSIONS: The method of analyzing zebrafish OMR using graded contrast gray-white stripes is more sensitive than the OMR assay alone and may be more useful for assessing the drug toxicity and eye-related diseases to improve the understanding of drug-induced ocular side effects in the clinic.

[The impact of digoxin on the long-term outcomes in patients with coronary artery disease and atrial fibrillation].

Objective: To investigate the long-term safety of digoxin in patients with coronary artery disease (CAD) and atrial fibrillation (AF). Methods: This was a prospective study, in which 25 512 AF patients were enrolled from China Atrial Fibrillation Registry Study. After exclusion of patients receiving ablation therapy at the enrollment, 1 810 CAD patients [age: (71.5±9.3)years] with AF were included. The subjects were grouped into the digoxin group and non-digoxin group, and were followed up for a period of 80 months. Long-term outcomes were compared between the groups and an adjusted Cox regression analysis was applied to evaluate the risk of digoxin on the long-term outcomes. The primary endpoint was all-cause mortality. Results: The patients were followed up for a median period of 3.05 years. After multivariable adjustment, the Cox regression analysis showed that digoxin significantly increased the risk of all-cause mortality (HR=1.28, 95%CI 1.01-1.61, P=0.038), cardiovascular mortality (HR=1.48,95%CI 1.10-2.00,P=0.010), cardiovascular hospitalization (HR=1.67,95%CI 1.35-2.07,P=0.008) and the composite endpoints (HR=2.02,95%CI 1.71-2.38,P<0.001). In the subgroup of patients with heart failure (HF), digoxin was not associated with the risk of all-cause mortality, but was still associated with the increased risk of cardiovascular mortality (HR=1.44,95%CI 1.05-1.98,P=0.025), cardiovascular hospitalization (HR=1.44,95%CI 1.09-1.90,P=0.010) and the composite endpoints (HR=1.37, 95%CI 1.01-1.70, P=0.004). However, in the subgroup of patients without HF, digoxin was only associated with all-cause mortality (HR=2.56,95%CI 1.44-4.54,P=0.001). Conclusion: Digoxin significantly increased the risk of all-cause mortality in CAD patients with AF, especially in patients without HF.

Effect of eliglustat on the pharmacokinetics of digoxin, metoprolol, and oral contraceptives and absorption of eliglustat when coadministered with acid-reducing agents.

Eliglustat is an oral substrate reduction therapy indicated for patients with Gaucher disease type 1. Based on in vitro data, clinical trials were conducted to assess the potential for drug-drug interactions between eliglustat and digoxin (P-glycoprotein substrate), metoprolol (sensitive CYP2D6 substrate), a combined oral contraceptive (CYP3A substrate), and acid-reducing agents. Healthy subjects were enrolled in four Phase 1 clinical studies to evaluate the effect of eliglustat on the pharmacokinetics, safety, and tolerability of digoxin (N = 28), metoprolol (N = 14), and a combined oral contraceptive (N = 30) and the effect of acid-reducing agents on eliglustat pharmacokinetics, safety, and tolerability (N = 24). Coadministration resulted in increased exposure to digoxin (1.49-fold) and metoprolol (2-fold) with eliglustat, negligible effects on oral contraceptive pharmacokinetics with eliglustat, and a negligible effect of acid-reducing agents on eliglustat pharmacokinetics. Across all studies, eliglustat was well-tolerated. One serious adverse event (spontaneous abortion) and one discontinuation due to an adverse event (urinary tract infection) were reported, both during the acid-reducing agents study. When eliglustat is coadministered with medications that are P-glycoprotein or CYP2D6 substrates, lower doses of these concomitant medications may be required. Eliglustat may be coadministered with oral contraceptives and acid-reducing agents without dose modifications for either drug.

Effect of Bisoprolol on the Level of Dabigatran.

BACKGROUND: Many patients receiving dabigatran treatment might also require bisoprolol therapy. However, there is a possibility that bisoprolol as significant P-glycoprotein inhibitor might interact with dabigatran. STUDY QUESTION: To investigate the impact of concomitant bisoprolol therapy on dabigatran plasma level in patients with nonvalvular atrial fibrillation. STUDY DESIGN: A pilot drug interaction study in 29 patients with nonvalvular atrial fibrillation on dabigatran therapy. Bisoprolol was administrated in 18 patients. Blood samples were collected at baseline (in the morning, before any medication was administered) and at hour 2 (2 hours after administration of dabigatran and bisoprolol). RESULTS: The dabigatran plasma level was significantly higher at baseline and at hour 2 in patients treated with bisoprolol compared with patients without bisoprolol therapy. In addition, we have shown that this increase is affected by dabigatran dosage and concomitant treatment with proton-pump inhibitor and digoxin. The impact of bisoprolol on dabigatran concentration was still significant despite these confounders. CONCLUSIONS: This study demonstrated the interaction between dabigatran and bisoprolol, which is modulated with dabigatran dosage and concomitant treatment with proton-pump inhibitor and digoxin.

Digoxin-mortality: randomized vs. observational comparison in the DIG trial.

AIMS: The Digitalis Investigation Group (DIG) trial, the only large randomized trial of digoxin in heart failure, reported a neutral effect on mortality and a significant reduction in heart failure hospitalizations. Recent observational studies reported increased mortality with digoxin treatment. We present further analyses of the DIG trial displaying the inability to control bias in observational treatment comparisons despite extensive statistical adjustments. METHODS AND RESULTS: Forty-four percent of the 6800 patients in the DIG trial had been treated with digoxin before randomization, and half of them were randomly withdrawn from digoxin treatment. We contrast the main randomization-based result of the DIG trial with the observational non-randomized comparison of patients pre-treated or not pre-treated with digoxin. Mortality [hazard ratio (HR) 1.22, 95% confidence interval (CI) 1.12-1.34; P < 0.001] and heart failure hospitalizations (HR 1.47, 95% CI 1.33-1.61; P < 0.001) were significantly higher in patients pre-treated with digoxin even after adjustment for baseline population differences. The higher risks for both outcomes in those who had previously received digoxin persisted even if they received placebo during the trial (HR 1.24, 95% CI 1.10-1.40; P < 0.001). This sharply contradicts the neutral effect on mortality and the significant reduction in heart failure hospitalizations observed in the randomized comparison. CONCLUSION: Prescription of digoxin is an indicator of disease severity and worse prognosis, which cannot be fully accounted for by covariate adjustments in the DIG trial where patients were well-characterized. It is unlikely that weaker research approaches (observational studies of administrative data or registries) can provide more reliable estimates of the effects of cardiac glycosides.

Effect of Digoxin vs Bisoprolol for Heart Rate Control in Atrial Fibrillation on Patient-Reported Quality of Life: The RATE-AF Randomized Clinical Trial.

Importance: There is little evidence to support selection of heart rate control therapy in patients with permanent atrial fibrillation, in particular those with coexisting heart failure. Objective: To compare low-dose digoxin with bisoprolol (a ß-blocker). Design, Setting, and Participants: Randomized, open-label, blinded end-point clinical trial including 160 patients aged 60 years or older with permanent atrial fibrillation (defined as no plan to restore sinus rhythm) and dyspnea classified as New York Heart Association class II or higher. Patients were recruited from 3 hospitals and primary care practices in England from 2016 through 2018; last follow-up occurred in October 2019. Interventions: Digoxin (n = 80; dose range, 62.5-250 µg/d; mean dose, 161 µg/d) or bisoprolol (n = 80; dose range, 1.25-15 mg/d; mean dose, 3.2 mg/d). Main Outcomes and Measures: The primary end point was patient-reported quality of life using the 36-Item Short Form Health Survey physical component summary score (SF-36 PCS) at 6 months (higher scores are better; range, 0-100), with a minimal clinically important difference of 0.5 SD. There were 17 secondary end points (including resting heart rate, modified European Heart Rhythm Association [EHRA] symptom classification, and N-terminal pro-brain natriuretic peptide [NT-proBNP] level) at 6 months, 20 end points at 12 months, and adverse event (AE) reporting. Results: Among 160 patients (mean age, 76 [SD, 8] years; 74 [46%] women; mean baseline heart rate, 100/min [SD, 18/min]), 145 (91%) completed the trial and 150 (94%) were included in the analysis for the primary outcome. There was no significant difference in the primary outcome of normalized SF-36 PCS at 6 months (mean, 31.9 [SD, 11.7] for digoxin vs 29.7 [11.4] for bisoprolol; adjusted mean difference, 1.4 [95% CI, -1.1 to 3.8]; P = .28). Of the 17 secondary outcomes at 6 months, there were no significant between-group differences for 16 outcomes, including resting heart rate (a mean of 76.9/min [SD, 12.1/min] with digoxin vs a mean of 74.8/min [SD, 11.6/min] with bisoprolol; difference, 1.5/min [95% CI, -2.0 to 5.1/min]; P = .40). The modified EHRA class was significantly different between groups at 6 months; 53% of patients in the digoxin group reported a 2-class improvement vs 9% of patients in the bisoprolol group (adjusted odds ratio, 10.3 [95% CI, 4.0 to 26.6]; P < .001). At 12 months, 8 of 20 outcomes were significantly different (all favoring digoxin), with a median NT-proBNP level of 960 pg/mL (interquartile range, 626 to 1531 pg/mL) in the digoxin group vs 1250 pg/mL (interquartile range, 847 to 1890 pg/mL) in the bisoprolol group (ratio of geometric means, 0.77 [95% CI, 0.64 to 0.92]; P = .005). Adverse events were less common with digoxin; 20 patients (25%) in the digoxin group had at least 1 AE vs 51 patients (64%) in the bisoprolol group (P < .001). There were 29 treatment-related AEs and 16 serious AEs in the digoxin group vs 142 and 37, respectively, in the bisoprolol group. Conclusions and Relevance: Among patients with permanent atrial fibrillation and symptoms of heart failure treated with low-dose digoxin or bisoprolol, there was no statistically significant difference in quality of life at 6 months. These findings support potentially basing decisions about treatment on other end points. Trial Registration: ClinicalTrials.gov Identifier: NCT02391337 and clinicaltrialsregister.eu Identifier: 2015-005043-13.

Rare Interaction of Warfarin and Digoxin in a Case of Digoxin Toxicity.

Warfarin is known to interact with many drugs and can lead to serious consequences. We report a case of 52 years old female patient from Himachal Pradesh. During hospital stay patient developed coagulopathy in form of INR above 10 and bradycardia with ventricular rate on ECG with digoxin level of 3.76 ng/ml. In this way digoxin toxicity was confirmed and it was considered as cause of coagulopathy after ruling out interactions of warfarin.

Resolution of Fetal Hydrops Dependent on Sustained Fetal Supraventricular Tachycardia after Digoxin Therapy.

We present a special case of fetal supraventricular tachycardia detected at 34 weeks gestation. Fetal hydrops was noted on ultrasound upon admission. Normal fetal heart rate was maintained for three weeks by maternal administration of digoxin. A live infant was delivered via caesarian section at 37 weeks gestation. This clinical case demonstrated that pharmacological treatment can be effective and helps to prolong pregnancy safely.