Warfarin is best suited, in areas of slowly-running blood, such as in veins
and the pooled blood behind artificial
and natural valves,
and pooled in dysfunctional cardiac atria. So common clinical indications for warfarin use are atrial fibrillation, the presence of artificial heart valves, deep venous thrombosis (clots), and pulmonary embolism (where the embolized clots first form in veins).