Early postoperative anticoagulation after mechanical valve replacement: a systematic review

Antithrombotic management of patients with prosthetic heart valves: current evidence and future trends

Over 4 million people worldwide have received a prosthetic heart valve, and an estimated 300,000 valves are being implanted every year. Prosthetic heart valves improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thrombotic complications in valve recipients poses challenges for clinicians and patients. Here, we review antithrombotic therapies for patients with prosthetic heart valves and management of thromboembolic complications. Advances in antithrombotic therapy and valve technologies are likely to improve the management of patients with prosthetic heart valves in developed countries, but the most important unmet need and potential for benefit from these new therapies is in developing countries where a massive and rapidly increasing burden of valvular heart disease exists.

Antithrombotic therapy in patients with prosthetic heart valves

Patients with mechanical valve prostheses require a lifelong anticoagulant treatment. The combined use of Warfarin and low-dose aspirin appears to reduce the risk of valve thrombosis and systemic embolism at a low risk of bleeding. The management of women with prosthetic heart valves during pregnancy poses a particular challenge, as there are no available controlled clinical trials to provide guidelines for effective antithrombotic therapy. Oral anticoagulants, such as Warfarin, cause foetal embryopathy; unfractionated heparin and low-molecular-weight heparin have been reported to be ineffective in preventing thromboembolic complications. This article discusses the available data and the most recent guidelines in the antithrombotic management of patients with prosthetic valves, and antithrombotic therapy in various clinical situations such as pregnant women with prosthetic heart valves, and patients with prosthetic heart valves undergoing noncardiac surgery.

Guideline on antiplatelet and anticoagulation management in cardiac surgery

This document presents a professional view of evidence-based recommendations around the issues of antiplatelet and anticoagulation management in cardiac surgery. It was prepared by the Audit and Guidelines Committee of the European Association for Cardio-Thoracic Surgery (EACTS). We review the following topics: evidence for aspirin, clopidogrel and warfarin cessation prior to cardiac surgery; perioperative interventions to reduce bleeding including the use of aprotinin and tranexamic acid; the use of thromboelastography to guide blood product usage; protamine reversal of heparin; the use of factor VIIa to control severe bleeding; anticoagulation after mechanical, tissue valve replacement and mitral valve repair; the use of antiplatelets and clopidogrel after cardiac surgery to improve graft patency and reduce thromboembolic complications and thromboprophylaxis in the postoperative period. This guideline is subject to continuous informal review, and when new evidence becomes available. The formal review date will be at 5 years from publication (September 2013).

Outpatient-Based Primary and Secondary Thromboprophylaxis With Low-Molecular-Weight Heparin

Although oral vitamin K antagonists such as warfarin have been the mainstay of thromboprophylaxis in the outpatient setting, warfarin has potential disadvantages, including food and drug interactions, the need for drug monitoring, intolerance, failure, and hypersensitivity syndromes. The use of low-molecular-weight heparin as a primary or secondary thromboprophylactic drug in the outpatient setting for extended prophylaxis or as outpatient bridging therapy has been addressed less extensively. Available evidence shows that low-molecular-weight heparin can be used as extended outpatient-based primary thromboprophylaxis for major orthopedic and cancer surgery and is a safe and effective alternative to warfarin in long-term secondary thromboprophylaxis, especially in cancer patients and in pregnant women. Low-molecular-weight heparin can also be used as an alternative to unfractionated heparin as outpatient-based bridging therapy. In addition to good clinical outcomes and financial benefits, mainly resulting from a reduction in the length of hospital stay, the use of extended-duration low-molecular-weight heparin in the outpatient setting appears to be feasible, with high patient compliance.

Aortic Valve Replacement With Mitral Valve Repair Compared With Combined Aortic and Mitral Valve Replacement

BACKGROUND

Double valve replacement is associated with reduced long-term survival. This study investigates aortic valve replacement with mitral valve repair as an alternative to double valve replacement in patients with rheumatic heart disease (RHD).

METHODS

Between January 1995 and December 2005, 369 patients with RHD underwent combined aortic and mitral valve procedures. In 76 patients (20.6%), mitral valve repair with aortic valve replacement (group 1) was done. The remaining 293 patients (79.4%) underwent double valve replacement (group 2). A total of 351 patients (95%)--73 (96%) in group 1 and 278 (94.8%) in group 2--were 50 years of age or younger.

RESULTS

There was no difference in early mortality in the groups (4 in group 1 versus 25 in group 2, p = 0.35). The median follow-up was 60 months (range, 6 to 132 months) and 96% complete in group 1 and 92% in group 2. Actuarial survival was 90.5% +/- 3.4% in group 1 and 81.60% +/- 2.4% in group 2 at 60 months (p = 0.07). Event-free survival at 60 months was 78.3% +/- 5.1% in group 1 and 48.4 % +/- 3.2% in group 2 (p < 0.001). Reoperation-free survival was 92.5% +/- 0.4% in group 1 and 99.5% +/- 0.05% in group 2 (p = 0.014).

CONCLUSIONS

Mitral valve repair with aortic valve replacement provides significantly better event-free survival than double valve replacement without a better actuarial survival. Reoperation rates are higher in the mitral valve repair and aortic valve replacement group, whereas thromboembolic complications were more in the double valve replacement group. Better event-free survival in patients undergoing mitral valve repair and aortic valve replacement still argues in favor of repair of the mitral valve whenever possible.

Challenges in managing anticoagulant therapy in patients with heart valve prostheses

There is a wide array of recommendations for the management of anticoagulant therapy in patients with mechanical heart valves. The optimal intensity of vitamin K antagonists, management of patients during noncardiac surgery and use of anticoagulants during pregnancy are all ongoing matters of debate. In this review, we discuss the various studies on these topics and the different guidelines. Based on these, literature recommendations for daily clinical practice are formulated.