Dronedarone for atrial fibrillation: a new therapeutic agent

Impact of dronedarone treatment on healthcare resource utilization in patients with atrial fibrillation/flutter

BACKGROUND

The ATHENA (A Placebo-Controlled, Double-Blind, Parallel Arm Trial to Assess the Efficacy of Dronedarone 400 mg bid for the Prevention of Cardiovascular Hospitalization or Death from Any Cause in Patients with Atrial Fibrillation/Atrial Flutter) trial demonstrated a significant reduction (26%) in the rate of first cardiovascular (CV) hospitalization in dronedarone-treated patients with paroxysmal or persistent atrial fibrillation/flutter (AF/AFL). ATHENA was the first trial to demonstrate a CV outcomes benefit, specifically reduced CV hospitalizations, with an antiarrhythmic drug. The objective of this study was to assess the impact of dronedarone treatment on healthcare resource utilization among real-world patients with AF/AFL in United States clinical practice.

METHODS

This retrospective cohort study used claims data from the MarketScan® databases (Truven Health, Durham, NC, USA) to identify patients with ≥2 concurrent de novo pharmacy claims for dronedarone (≥180 days' total supply) between June 2009 and March 2011, and with an AF/AFL diagnosis and no heart failure-related hospitalization during the 12 months preceding the initial (index) dronedarone claim. Annualized inpatient and outpatient resource utilization were compared between the pre-index (baseline) and post-index (follow-up) periods.

RESULTS

In total, 5,656 AF/AFL patients were prescribed dronedarone for ≥6 months and were followed for mean (standard deviation) 11.9 (4.7) months. Reductions in mean numbers of annualized all-cause, CV- and AF-related hospitalizations (~40-45%), and emergency department visits (~30-45%) were realized. These benefits were offset by increases in office visits (~10-30%) and AF-related prescription claims (74%) after dronedarone initiation. The sub-cohort of patients switching to dronedarone from Prior Rhythm-Control therapy (n=2,080) showed similar reductions in hospital and emergency department events.

CONCLUSIONS

This study suggests that dronedarone use in real-world practice, as in the ATHENA trial, results in substantial reductions in hospital admissions, both in first-line and second-line antiarrhythmic treatment settings.

Crebanine inhibits voltage-dependent Na+ current in guinea-pig ventricular myocytes

AIM

To study the effects of crebanine on voltage-gated Na(+) channels in cardiac tissues.

METHODS

Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltage-dependent Na(+) current was recorded using the whole cell voltage-clamp technique.

RESULTS

Crebanine reversibly inhibited Na(+) current with an IC50 value of 0.283 mmol·L(-1) (95% confidence range: 0.248-0.318 mmol·L(-1)). Crebanine at 0.262 mmol·L(-1) caused a negative shift (about 12 mV) in the voltage-dependence of steady-state inactivation of Na(+) current, and retarded its recovery from inactivation, but did not affect its activation curve.

CONCLUSION

In addition to blocking other voltage-gated ion channels, crebanine blocked Na(+) channels in guinea-pig ventricular myocytes. Crebanine acted as an inactivation stabilizer of Na(+) channels in cardiac tissues.

Safety and efficacy of dronedarone in the treatment of atrial fibrillation/flutter

Dronedarone is an amiodarone analog but differs structurally from amiodarone in that the iodine moiety was removed and a methane-sulfonyl group was added. These modifications reduced thyroid and other end-organ adverse effects and makes dronedarone less lipophilic, shortening its half-life. Dronedarone has been shown to prevent atrial fibrillation/flutter (AF/AFl) recurrences in several multi-center trials. In addition to its rhythm control properties, dronedarone has rate control properties and slows the ventricular response during AF. Dronedarone is approved in Europe for rhythm and rate control indications. In patients with decompensated heart failure, dronedarone treatment increased mortality and cardiovascular hospitalizations. However, when dronedarone was used in elderly high risk AF/AFl patients excluding such high risk heart failure, cardiovascular hospitalizations were significantly reduced and the drug was approved in the USA for this indication in 2009 by the Food and Drug Administration. Updated guidelines suggest dronedarone as a front-line antiarrhythmic in many patients with AF/Fl but caution that the drug should not be used in patients with advanced heart failure. In addition, the recent results of the PALLAS trial suggest that dronedarone should not be used in the long-term treatment of patients with permanent AF.

Dronedarone: current evidence for its safety and efficacy in the management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia. Management of AF includes rate control, rhythm control if necessary, prevention of thromboembolic events, and treatment of the underlying disease. Rate control is usually achieved by pharmacological suppression of calcium currents or by applying β-blockers or digitalis compounds. In contrast, the number of compounds available for rhythm control is still limited. Class Ic agents increase mortality in patients with structural heart disease, and amiodarone harbors an extensive side effect profile despite its efficacy in maintaining sinus rhythm. Furthermore, rhythm control by these compounds has not been shown to reduce patient mortality. Dronedarone is a new anti-arrhythmic drug that has been developed to provide rhythm and rate control in AF patients with fewer side effects compared with amiodarone. This review primarily focuses on clinical trials evaluating efficacy and safety of the novel drug. Conclusions from these studies are critically reviewed, and recommendations for clinical practice are discussed. Dronedarone significantly reduced the incidence of hospitalization due to cardiovascular events or death in high-risk patients with atrial fibrillation (ATHENA trial). However, dronedarone was less efficient than amiodarone in maintaining normal sinus rhythm (DIONYSOS trial) and is contraindicated in severe or deteriorating heart failure (ANDROMEDA trial). In summary, dronedarone represents a valuable addition to the limited spectrum of antiarrhythmic drugs and is currently recommended in patients with paroxysmal and persistent AF to achieve rate and rhythm control, excluding cases of severe or unstable congestive heart failure.