Atrial fibrillation (AF) and Venous Thromboembolism (VTE) are long term conditions affecting millions of people globally. AF is one of the major risk factors for stroke. While Vitamin K antagonists (VKAs) such as warfarin has been the traditional standard of care for over sixty years, the introduction of Direct Oral Anticoagulants (DOACs) have given physicians and patients an additional treatment options for stroke prevention in AF and for the treatment of VTE. In this part one of the four-part whitepaper, we start with the introduction to AF and VTE and the current standard of care.