Apixaban Versus Warfarin in the Evaluation of Progression of Atherosclerotic Calcification and Vulnerable Plaque

Vitamin K-antagonists (VKA) such as warfarin are the most widely used blood thinners for irregular heart beats like atrial fibrillation. Several lines of evidence indicate, however, that these agents also cause calcification of vessels (hardening of the vessels). Vascular calcification is one of the recently revealed side-effects of warfarin therapy. We will be randomizing 66 patients to either take warfarin or a new blood thinner that works without affecting vitamin k (apixaban). Patients will undergo blood testing and a CT angiogram (non-invasive angiogram) at the beginning of the study, and then be followed for one year with quarterly visits including blood tests and given either warfarin or vitamin K. After one year, they will undergo another CT angiogram and examination and blood tests and the effect of apixaban and warfarin are tested to look at plaque and changes over time. Patients will be consented in a private room and the risks and benefits will be explained. The risks include the CT angiogram and the possibility of either remaining on warfarin therapy for another year (standard of care) or taking a medicine that doesn't require monitoring (apixaban) for one year. The CT angiograms will require some contrast and some radiation dose, which will be minimized as much as possible. A cardiologist will be present during each CT angiogram to minimize risk and ensure patient safety.