Atrial fibrillation (AF) is the most common type of cardiac arrhythmia, affecting an estimated 4.5 million people in the EU. AF mainly affects the elderly population and it is estimated that 5-10% of the population above the age of 70 have AF. The increasing elderly population is one of the reasons for the expected increase in the prevalence of AF, which in the US has been projected to increase from 2.2 million patients in 2006 to 5.6-15.9 million in 2050. The lifetime risk for developing AF is 25% for individuals over 40 years of age.
AF is associated with impaired quality of life, increased rate of hospitalisation, and increased risk of stroke and death. AF-related strokes are estimated to account for up to 20% of all strokes, and the expected dramatic rise in the numbers of AF patients predict a major increase in the economic burden of AF.
AF patients are often treated with antiarrhythmic drugs as well as anticoagulants to prevent stroke, but also invasive ablation techniques such as pulmonary vein isolation are used as a treatment in some AF patients.
Antiarrhythmic treatment of AF with drugs can be divided into:
'Acute cardioversion' of AF, aimed to bring the heart back to its normal rhythm (sinus rhythm)
'Maintenance therapy', a chronic drug therapy aimed to maintain sinus rhythm and prevent recurrence of AF
Acute cardioversion of a sustained AF can be obtained by pharmacological treatment (antiarrhythmic drug) or by electrical cardioversion (electrical shock). Electrical cardioversion has a very high efficacy in converting AF into normal heart rhythm but also has the disadvantage that general anesthesia and fasting is required before the cardioversion. For pharmacological cardioversion a number of drugs are approved, but it is however recognized that these existing drug therapies only have a limited effect and/or is followed by risks of serious adverse events. Therefore, there is a high unmet need for developing better drugs for the medical treatment of AF.
Maintenance therapy is pharmacological therapy aimed to maintain the normal heart rhythm. Many of these drugs are identical to those used for acute cardioversion and therefore have the same efficacy and/or safety issues. An often used alternative to these anti-arrhythmic drugs is to prescribe beta-blockers that reduce the overall heart rate, however without restoring normal rhythm in the atria.