Digoxin in Atrial Fibrillation: An Old Topic Revisited

A case of digoxin intoxication caused by short-term massive overdose: Case report

RATIONALE

Digoxin is a frequently prescribed medication for the management of both acute and chronic cardiac insufficiency. The overdose ingestion of digoxin can result in a range of arrhythmias, with severe cases potentially leading to malignant arrhythmias and fatal outcomes. To date, there is a lack of documented cases related to acute digoxin intoxication resulting from the administration of massive digoxin overdose in the short term.

PATIENT CONCERNS

A 37-year-old female patient was admitted to the emergency department following a suicide attempt involving the administration of 330 tablets of digoxin (each tablet containing 0.25 mg). The patient exhibited symptoms of confusion, nausea, and vomiting for around 30 minutes. The patient had a history of depression.

DIAGNOSES

The patient was diagnosed with digoxin intoxication.

INTERVENTIONS

The patient underwent many medical interventions including stomach lavage, administration of laxatives, correction of cardiac arrhythmias, provision of myocardial nutrition, diuresis, correction of acid-base balance, and management of electrolyte disturbances, among others.

OUTCOMES

Following a treatment of 9 days, the patient exhibited no signs of discomfort, maintained consciousness, and the serum concentration of digoxin was indeterminable. Upon reevaluation of the electrocardiogram, it was determined that no arrhythmia was present. Consequently, the patient was authorized to be discharged from the hospital.

CONCLUSIONS

There is currently no documented evidence of cases involving a significant overdose of digoxin resulting in intoxication. The patient had a comprehensive treatment regimen consisting of stomach lavage, administration of a laxative, correction of cardiac arrhythmias, provision of myocardial nutrition, fluid replacement, diuresis, and supportive therapy, resulting in successful outcomes.

LESSONS

There have been no known cases of intoxication resulting from a significant overdose of digoxin, specifically with the consumption of 330 tablets (0.25 mg/tablet). However, in the event of ingesting excessive amounts of digoxin, it is imperative to promptly administer stomach lavage, administration of a laxative, and arrhythmia correction. The administration of temporary pacemaker therapy is recommended for patients presenting with high atrioventricular block, whereas hemoperfusion is advised for patients with renal insufficiency as a means to eliminate digoxin from the body.

The Optimal Management of Patients with Atrial Fibrillation and Acute Heart Failure in the Emergency Department

Atrial fibrillation (AF) and acute heart failure (AHF) are two closely interrelated conditions that frequently coexist in a manifold manner, with AF serving either as the causative factor or as the consequence or even as an innocent bystander. The interplay between these two clinical conditions is complex, given that they share common pathophysiological pathways and they can reciprocally exacerbate each other, thus triggering a vicious cycle that worsens the prognosis and increases the thromboembolic risk. The optimal management of AF in the context of AHF in the emergency department remains a challenge depending on the time onset, as well as the nature and the severity of the associated symptoms. Acute rate control, along with early rhythm control, when indicated, and anticoagulation represent the main pillars of the therapeutic intervention. The purpose of this review is to elucidate the pathophysiological link between AF and AHF and accordingly present a stepwise algorithmic approach for the management of AF in AHF patients in the emergency setting.

Antiarrhythmic drugs for atrial fibrillation in the outpatient setting

With burgeoning evidence for early rhythm control in patients with atrial fibrillation (AF), the management of AF in the outpatient setting has become more challenging. The primary care clinician often serves as the frontline in the pharmacologic management of AF. Because of drug interactions and the risk of proarrhythmia, many clinicians remain hesitant about the initiation and chronic management of antiarrhythmic drug prescriptions. However, with the likely increased use of antiarrhythmics for early rhythm control, understanding and familiarity with these medications have likewise become more important, especially since patients with AF probably have other non-cardiac medical conditions that can impact their antiarrhythmic therapy. In this comprehensive review, we provide informative, high-yield cases and edifying references that will help primary care providers become comfortable handling various clinical scenarios.

Safety and Efficacy of Nondihydropyridine Calcium Channel Blockers for Acute Rate Control in Atrial Fibrillation with Rapid Ventricular Response and Comorbid Heart Failure with Reduced Ejection Fraction

The use of nondihydropyridine calcium channel blockers (NDCCBs) to achieve rate control in atrial fibrillation with the rapid ventricular rate (AF RVR) is not recommended in patients with comorbid heart failure with reduced ejection fraction (HFrEF) due to the concern for further blunting of contractility. However, these recommendations are extrapolated from data examining chronic NDCCB use in HFrEF patients, and comorbid AF was not analyzed. These recommendations also do not cite the hemodynamic effects or clinical outcomes of NDCCBs for acute rate control in HFrEF patients with AF RVR. It is our goal to open the discussion concerning the hemodynamic effects and safety profile of NDCCBs for acute rate control in this specific patient population. In the acute setting of AF RVR and HFrEF, there is a paucity of low-quality data on the safety and hemodynamic effects of NDCCBs, with mixed results. There has not been a clear signal toward adverse outcomes with NDCCBs, particularly for diltiazem. Data in this scenario is similarly limited for beta blockers, which provide the additional hemodynamic effect of the neurohormonal blockade, which provides a long-term mortality benefit to HFrEF patients. We support the cautious use of beta blockers as first-line therapy in clinical settings where an acute rate control strategy for AF RVR is warranted. We also support diltiazem as a reasonable second-line option, though the relative paucity of data calls for further research to validate this conclusion. Verapamil in this setting should be avoided until more data are available.

Strategies for rate and rhythm control of atrial fibrillation in the ED

ABSTRACT

Atrial fibrillation (AF) is one of the most common dysrhythmias managed in the ED and accounts for more than half a million visits a year in the United States. More than 6 out of 10 of these visits result in admissions. As the prevalence of AF has continued to increase in recent years, so has the presentation of patients with AF to the ED. For these reasons, clinicians in emergency settings must be knowledgeable of evidence-based rate and rhythm control strategies for stabilizing patients and preventing complications. This article discusses options, indications, contraindications, and safe implementation of rate and rhythm control strategies for ED clinicians. Recent studies have suggested that early rhythm control may benefit newly diagnosed patients, reducing stroke risk, cardiovascular deaths, and disease progression.

Research Progress in Pharmacological Activities and Applications of Cardiotonic Steroids

Cardiotonic steroids (CTS) are a group of compounds existing in animals and plants. CTS are commonly referred to cardiac glycosides (CGs) which are composed of sugar residues, unsaturated lactone rings and steroid cores. Their traditional mechanism of action is to inhibit sodium-potassium ATPase to strengthen the heart and regulate heart rate, so it is currently widely used in the treatment of cardiovascular diseases such as heart failure and tachyarrhythmia. It is worth noticing that recent studies have found an avalanche of inestimable values of CTS applications in many fields such as anti-tumor, anti-virus, neuroprotection, and immune regulation through multi-molecular mechanisms. Thus, the pharmacological activities and applications of CTS have extensive prospects, which would provide a direction for new drug research and development. Here, we review the potential applications of CTS in cardiovascular system and other systems. We also provide suggestions for new clinical practical strategies of CTS, for many diseases. Four main themes will be discussed, in relation to the impact of CTS, on 1) tumors, 2) viral infections, 3) nervous system diseases and 4) immune-inflammation-related diseases.

Cellular Mechanisms Underlying the Low Cardiotoxicity of Istaroxime

Background

Istaroxime is an inhibitor of Na⁺/K⁺ ATPase with proven efficacy to increase cardiac contractility and to accelerate relaxation attributable to a relief in phospholamban‐dependent inhibition of the sarcoplasmic reticulum Ca²⁺ ATPase. We have previously shown that pharmacologic Na⁺/K⁺ ATPase inhibition promotes calcium/calmodulin‐dependent kinase II activation, which mediates both cardiomyocyte death and arrhythmias. Here, we aim to compare the cardiotoxic effects promoted by classic pharmacologic Na⁺/K⁺ ATPase inhibition versus istaroxime.

Methods and Results

Ventricular cardiomyocytes were treated with ouabain or istaroxime at previously tested equi‐inotropic concentrations to compare their impact on cell viability, apoptosis, and calcium/calmodulin‐dependent kinase II activation. In contrast to ouabain, istaroxime neither promoted calcium/calmodulin‐dependent kinase II activation nor cardiomyocyte death. In addition, we explored the differential behavior promoted by ouabain and istaroxime on spontaneous diastolic Ca²⁺ release. In rat cardiomyocytes, istaroxime did not significantly increase Ca²⁺ spark and wave frequency but increased the proportion of aborted Ca²⁺ waves. Further insight was provided by studying cardiomyocytes from mice that do not express phospholamban. In this model, the lower Ca²⁺ wave incidence observed with istaroxime remains present, suggesting that istaroxime‐dependent relief on phospholamban‐dependent sarcoplasmic reticulum Ca²⁺ ATPase 2A inhibition is not the unique mechanism underlying the low arrhythmogenic profile of this drug.

Conclusions

Our results indicate that, different from ouabain, istaroxime can reach a significant inotropic effect without leading to calcium/calmodulin‐dependent kinase II–dependent cardiomyocyte death. Additionally, we provide novel insights regarding the low arrhythmogenic impact of istaroxime on cardiac Ca²⁺ handling.