Atrial fibrillation is the most prevalent cardiac arrhythmia, which is most prominent in the elderly. Today's drug options available for the treatment of atrial fibrillation are restricted due to insufficient efficacy, but even more so due to unwanted side effects, especially proarrhythmogenicity. This book focuses on atrial fibrillation and reviews different aspects of this increasingly common disorder including its pathophysiology, epidemiology and current therapy. It evaluates progress achieved by molecular biology over recent years in identifying ion channel proteins and genetic defects related to this disease. It also highlights new avenues of current research aiming to discover more effective and safer medicines for the treatment of atrial fibrillation.