Outcomes of warfarin therapy: lessons from the real world

Anticoagulation management in clinical practice: preventing stroke in patients with atrial fibrillation

Atrial fibrillation (AF) is a major and widely recognized risk factor for cardioembolic stroke. Prophylactic therapy for the prevention of stroke in patients with AF is often achieved through oral anticoagulation, specifically with warfarin, which has been used for this purpose for more than 50 years. Although warfarin therapy is effective when implemented appropriately, it is often underutilized and requires consistent monitoring to ensure both safety in avoiding bleeding and efficacy in preventing strokes. Because the burden of AF-related stroke continues to rise, healthcare professionals need to understand the strengths and limitations of current and emerging treatment options. This review outlines current practices for managing the risk of stroke with anticoagulation in patients with AF, and discusses how new oral anticoagulants may affect clinical practice.

Managing Complications of Anticoagulant Therapy

Understanding the frequency, risk factors, and management of anticoagulant-induced adverse events will assist clinicians in optimizing patient outcomes. The most frequent adverse event of all anticoagulants is major bleeding. Risk factors for major bleeding have been identified with the heparin compounds, the direct thrombin inhibitors (DTIs), fondaparinux, and warfarin therapy. Understanding these risk factors can help prevent bleeding events. For cases of clinically significant bleeding, reversal agents exist primarily for heparin and warfarin. Although less common, nonbleeding adverse events of anticoagulant therapy can also be life threatening. The heparin compounds are associated with the development of heparin-induced thrombocytopenia (HIT) and osteoporosis. HIT can result in life-threatening thrombosis and is usually managed with a DTI. Nonbleeding adverse events with warfarin therapy include skin reactions and the development of venous limb gangrene. Appropriate initiation of warfarin therapy may decrease the risk of venous limb gangrene.

Development of a decision aid for atrial fibrillation who are considering antithrombotic therapy

With patients demanding a greater role in the clinical decision-making process, many researchers are developing and disseminating decision aids for various medical conditions. In this article, we outline the essential elements in the development and evaluation of a decision aid to help patients with atrial fibrillation choose, in consultation with their physicians, appropriate antithrombotic therapy (warfarin, aspirin, or no therapy) to prevent stroke. We also outline possible future directions regarding the implementation and evaluation of this decision aid. This information should enable clinicians to better understand the role that decision aids may have in their interactions with patients.

Oral anticoagulant treatment in patients with mechanical heart valves: how to reduce the risk of thromboembolic and bleeding complications

Patients with mechanical heart valves have a high risk of thrombus formation on the valve and subsequent systemic embolism. These patients therefore need to receive life-long oral anticoagulation (OAC). Despite this treatment, the overall incidence rate of major thromboembolic complications is still about 1-2 per 100 patient-years. Additionally, these patients have an increased risk of bleeding complications, ranging between 1 and 7 per 100 patient-years. To reduce both types of often very serious complications, the optimal intensity of anticoagulation needs to be established. We found a fairly wide optimal range between 2.5 and 4.9 INR (international normalized ratio) at which the incidence of both untoward events was minimal. As a target intensity, we recommend opting for the middle of this range (INR 3.0-4.0), thereby providing a safe margin at both ends. In order to further reduce thromboembolic and bleeding complications, two approaches can be considered: first of all, the management of OAC treatment needs to be optimized in order to achieve a stable therapeutic effect in as many patients as possible. Secondly, patient characteristics need to be identified that increase the thromboembolic or bleeding risk. Subsequently, the optimal intensity may need to be adjusted accordingly, at an individual level. Possible risk factors for an increased thromboembolic risk are position and type of the prosthesis. Age may increase both the risk of thromboembolism and the risk of haemorrhage.