A 58-year-old man with a history of severe, symptomatic, chronic mitral regurgitation without left ventricular dysfunction presents to your clinic after recently moving for a new job. He underwent mitral valve replacement with mechanical valve prosthesis five years ago, and has been asymptomatic ever since. He takes warfarin 5 mg and aspirin 81 mg daily but wonders if he can transition to a different drug without regular monitoring. Additionally, he reports concern over taking both aspirin and warfarin because a close friend was recently hospitalized for a gastrointenstinal bleed, and requests discontinuation of his aspirin.
Which of the following is the most appropriate antithrombotic strategy for this patient?
Show Answer
The correct answer is: A) Continue current regimen of warfarin and aspirin.
This case raises several issues about the optimal management of antithrombotic therapy following mechanical valve prosthesis. For patients requiring mitral valve replacement, bioprosthetic valves are preferentially chosen in patients over 65 years of age or in those unable to take warfarin therapy given their limited durability and absence of requirement for lifelong anticoagulation. In patients under the age of 65 requiring valve replacement, mechanical valves are preferred. Mechanical mitral valves are increasingly rare in clinical practice due to grade 1C recommendations for mitral valve repair rather than replacement if a patient has appropriate anatomy. However, mitral valve replacement can often be seen in patients coming from less experienced centers or developing countries; thus, it is important for practitioners to be familiar with optimal management strategies.
Lifelong anticoagulation therapy is needed in all patients with mechanical mitral valve prosthesis.1 Vitamin K antagonists (e.g., warfarin) have been shown to be superior to antiplatelet therapy (e.g., clopidogrel, aspirin) in patients with mechanical valve prosthesis due to excessive thromboembolic events in patients taking antiplatelet therapy alone (answer option D).2
The use of aspirin in mechanical valve prosthesis has been debated. In a trial comparing low-dose aspirin with placebo in 370 patients who had undergone valve replacement, the combination of aspirin with warfarin was associated with a significant decrease in cardiovascular death in the group with mechanical valve replacement.3 It has been suggested that this benefit is mediated by the prevention of atherosclerotic disease complications rather than prosthesis complications, since 30% of the patients had atherosclerosis and the mortality reduction was primarily due to deaths from heart failure, myocardial infarction, and sudden death (rather than stroke).4 U.S. consensus groups have recommended the addition of aspirin to warfarin after mechanical mitral valve prosthesis provided the patient does not have increased bleeding risk, and European guidelines suggest aspirin use in patients with concomitant atherosclerosis or breakthrough thromboembolic disease despite adequate internationalized normal ratio (INR) (answer option B).5-7
Novel anticoagulants are not recommended in the prevention of thromboembolic complications following mechanical valve prosthesis (answer options C and E). This is due primarily to the results of the Randomized, Phase II Study to Evaluate the Safety and Pharmacokinetics of Oral Dabigatran Etexilate in Patients after Heart Valve Replacement (RE-ALIGN) trial, in which patients with mechanical prostheses treated with dabigatran demonstrated excess thromboembolism and bleeding compared to those randomized to warfarin.8
In summary, this patient will benefit from continuation of lifelong warfarin and aspirin therapy provided his bleeding risk remains low and until further data becomes available about the use of novel anticoagulants following mechanical valve prosthesis (answer option A).
References
Bonow RO, Carabello BA, Chatterjee K, et al. 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol 2008;52:e1-142.
Cannegieter SC, Rosendaal FR, Briet E. Thromboembolic and bleeding complications in patients with mechanical heart valve prostheses. Circulation 1994;89:635-41.
Turpie AG, Gent M, Laupacis A, et al. A comparison of aspirin with placebo in patients treated with warfarin after heart-valve replacement. N Engl J Med 1993;329:524-9.
Iung B, Rodes-Cabau J. The optimal management of anti-thrombotic therapy after valve replacement: certainties and uncertainties. Eur Heart J 2014;35:2942-9.
Joint Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology (ESC), European Association for Cardio-Thoracic Surgery (EACTS), Vahanian A, et al. Guidelines on the management of valvular heart disease (version 2012). Eur Heart J 2012;33:2451-96.
Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;63:2438-88.
Whitlock RP, Sun JC, Fremes SE, et al. Antithrombotic and thrombolytic therapy for valvular disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012;141:e576S-600S.
Eikelboom JW, Connolly SJ, Brueckmann M, et al. Dabigatran versus warfarin in patients with mechanical heart valves. N Engl J Med 2013;369:1206-14.
Log in to MyACC
