Bayer Pharma AG


Atrial fibrillation is a major risk factor for stroke

Atrial fibrillation is a major risk factor for stroke

The incidence of stroke in patients with atrial fibrillation (AF) is 2–17 times greater than in the general population, depending on the cause of AF. In addition, cardioembolic stroke is one of the most common complications of AF. The risk of stroke in patients with AF is also dependent on several risk factors, including age, with older patients being at higher risk. Several risk assessment tools are available to clinicians to help estimate the risk of stroke. One well-validated and widely-used tool is the CHA2DS2-VASc score, which identifies both major risk factors and clinically relevant non-major risk factors.


Weighing up the benefits and risks of therapy

The use of anticoagulants to reduce the risk of stroke should be balanced against safety, compliance and monitoring issues, and clinical decisions must always balance the benefits and risks of any treatment option. The main complication associated with anticoagulant and antiplatelet use is bleeding. Bleeding risk varies with age and is substantially higher in older patients. HAS-BLED is one user-friendly score that is used to assess the 1-year risk of major bleeding in a patient. This tool has demonstrated good predictive accuracy, but it should only be used as one of several factors to be considered by clinicians.


Cardioversion and anticoagulation

Electrical or pharmacological cardioversion is performed to attempt to re-establish a normal sinus rhythm in patients with non-valvular atrial fibrillation (AF). Electrical cardioversion is the preferred method for patients who present with persistent AF or those who are haemodynamically unstable. Stable patients or those with long-standing AF may receive either electrical or pharmacological cardioversion. Cardioversion success rates vary and AF will recur in approximately half of patients whose sinus rhythm is successfully normalized. Factors predicting the success of cardioversion are not well established but may include a shorter versus longer duration of AF. Duration and type of AF, concomitant diabetes and alcohol consumption may help to predict likely AF recurrence in patients who are successfully cardioverted.


Investigational Strategies

Several new anticoagulants that target various factors of the coagulation cascade are in development. These include tecarfarin and betrixaban.


Anticoagulants

Currently approved agents for the prevention of stroke in patients with atrial fibrillation (AF) include vitamin K antagonists (VKAs) and the novel oral anticoagulants (OACs) dabigatran, rivaroxaban, apixaban and edoxaban. VKAs, such as warfarin and acenocoumarol, are the most widely used medications for preventing thrombosis in patients with AF and, although they have proven benefit, they lack many properties of an ideal anticoagulant, such as rapid onset of action and predictable pharmacokinetics and pharmacodynamics. The novel OACs have many of these ideal properties and, therefore, have the potential to improve the quality of care. For this reason, the updated European Society of Cardiology (ESC) 2012 guidelines on the management of patients with AF recommend that novel OACs should be considered rather than adjusted-dose VKA (international normalized ratio [INR] 2.0–3.0) for most patients with non-valvular AF, based on their net clinical benefit.


Other Options

AtriClip™, a left atrial appendage (LAA) occlusion device, was approved in the United States (US) in 2010 for use in patients who are undergoing open-heart surgery and also have atrial fibrillation (AF) or a strong risk of developing AF. In a study of the percutaneous LAA occlusion device, WATCHMAN™, the device was found to be non-inferior to warfarin for the prevention of stroke, systemic embolism, cardiovascular or unexplained death in patients with non-valvular AF and a CHADS2 score of ≥1. However, the device was also associated with a higher risk of adverse events.