Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. 12 Congestive Heart Failure Symptoms, Stages, Causes, and Life Expectancy Congestive heart failure (CHF) refers to a condition in which the heart loses the ability to function properly. Heart disease. Conventional anticoagulants have proven efficacy in the management of thromboembolism. Their adverse effects and a narrow therapeutic window, necessitating regular need for monitoring, however, have long been an incentive for the development of safer anticoagulants without compromising efficacy. Congestive heart failure impairs the heart’s ability to pump blood efficiently and can lead to a number of complications. Sluggish blood flow due to heart failure can increase the risk of blood clots as well as abnormal heart rhythms that can lead to stroke. Coumadin, also known as Warfarin, is a medication originally extracted from coumarin, a chemical found in some plants. It suppresses the body's ability to form blood clots, by blocking the function of vitamin K. New Clots in Spite of Being on Warfarin – “Warfarin Failure” Stephan Moll, MD writes… Occasionally, new blood clots (DVT or PE) develop in spite of a patient being on warfarin (Coumadin, Jantoven). While some patients report that Coumadin causes Kidney Failure, others say it doesn't. Warfarin Failure Stephan Moll, MD writes… Occasionally, recurrent DVT or PE occur in spite of warfarin therapy, particularly in patients with (a) fluctuating and sub-therapeutic INRs, (b) lupus anticoagulant/ antiphospholipid antibody (APLA) syndrome or (c) cancer. Despite major advances in the management of heart failure with angiotensin-converting–enzyme inhibitors, beta-blockers, and resynchronization therapy, there are more than 1 million. Coumadin is an anticoagulant (blood thinner). Warfarin reduces the formation of blood clots. Coumadin is used to treat or prevent blood clots in veins or arteries, which can reduce the risk of stroke, heart attack, or other serious conditions.