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The treatment of unprovoked venous thromboembolism (VTE) is anticoagulant therapy for at least 3 months [1]. As VTE recurs frequently and about 20 % of the patients with an unprovoked VTE develop recurrence within the first 2 years [2], extended vitamin K antagonist (VKA) treatment is often considered. The decision to prolong VKA therapy after the initial treatment period is a dilemma, since longer term therapy reduces the risk of recurrent thromboembolism, but increases the risk of bleeding. The last American College of Chest Physicians (ACCP) EvidenceBased Clinical guidelines suggest a strategy to balance the benefits and risks of different durations of anticoagulant therapy; in unprovoked VTE, ACCP guidelines suggest extended anticoagulant therapy if bleeding risk is low or moderate (Grade 2B) and recommend 3 months of therapy if bleeding risk is high. When extended anticoagulant therapy is contraindicated, aspirin might be appealing. In fact the annual risk of major bleeding is only 0.1 % in patients on long-term low-dose aspirin therapy, thus lower than VKA therapy [3]. A large meta-analysis by the Antiplatelet Trialists’ Collaboration shows that antiplatelet therapy significantly reduces the risk of fatal or non-fatal pulmonary embolism (PE) by 25 % [3]. Moreover, a large trial involving patients undergoing surgery for hip fracture shows a 36 % risk reduction in VTE in the aspirin therapy group, [4] suggesting that antiplatelet therapy may be an alternative to prolonged VKA therapy. Two randomized controlled studies were conducted to evaluate the use of ASA for the prevention of venous thromboembolism recurrence: the Aspirin for the Prevention of Recurrent Venous Thromboembolism (Warfarin and Aspirin [WARFASA]) [5] and the Aspirin to Prevent Recurrent Venous Thromboembolism (ASPIRE) study [6].

BACKGROUND Atrial fibrillation (AF) is the most common sustained arrhythmia. It occurs in 1%-2% of the general population and its prevalence increases with age. Dronedarone, a noniodinated benzofuran similar to amiodarone, was developed as an antiarrhythmic agent for patients with atrial fibrillation. The aim of our systematic review was to critically evaluate randomized controlled trials that compared treatment with dronedarone versus placebo or amiodarone in patients with atrial fibrillation. METHODS Electronic databases (MEDLINE, Embase, and Central) were searched up to November 2011 with no language restrictions. We included randomized controlled trials in which dronedarone was compared to placebo or other drugs in patients with AF. Internal and external validity was assessed. RESULTS We identified seven papers corresponding to eight randomized controlled trials. The DAFNE, EURIDIS/ADONIS, and ATHENA trials demonstrated a reduction of AF recurrence with dronedarone as compared to placebo in patients with nonpermanent AF. The DIONYSOS study showed that dronedarone is less effective for the prevention of recurrent AF but improved tolerability as compared to amiodarone. Considering patients with permanent AF, the ERATO trial showed that dronedarone had rate-control effects while the PALLAS study was stopped early since stroke, myocardial infarction, systemic embolism, or death from cardiovascular causes were significantly more frequent in subjects treated with dronedarone as compared to placebo. The ANDROMEDA trial included patients with recent hospitalization for heart failure and was terminated early because of excess of deaths in the dronedarone group. CONCLUSION Like most antiarrhythmic drugs, dronedarone reduces the recurrence of AF in patients with paroxysmal or persistent AF as compared to placebo. However, relapse rates in the first year of therapy are high. Moreover, dronedarone showed to be less effective than amiodarone. Finally, dronedarone should be avoided in patients with permanent AF and a high risk for cardiovascular events or severe congestive heart failure.