Interact CardioVasc Thorac Surg 2006;5:761-765. doi:10.1510/icvts.2006.143099
© 2006 European Association of Cardio-Thoracic Surgery
Best evidence topic - Valves |
Is short-term anticoagulation necessary after mitral valve repair?
Sanjay Asopaa,
Anish Patela and
Joel Dunningb,*
a Wessex Cardiothoracic Unit, Southampton General Hospital, Southampton, UK
b Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, UK
Received 29 August 2006;
accepted 30 August 2006
*Corresponding author. Tel./fax: +44-780-1548122.
E-mail address: joeldunning{at}doctors.org.uk (J. Dunning).
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Abstract
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A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether oral anticoagulants are necessary after mitral valve repair. The reported search found 127 papers of which 12 represented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group, relevant outcomes and weaknesses were tabulated. We conclude that the current European Society of Cardiology guidelines support the use of warfarin for 3 months post-mitral repair, citing an absence of studies supporting the safety of omitting warfarin. They acknowledge that this is based on expert consensus and that many surgeons do not follow this guideline. No other guidelines provide recommendations in this area. The longest follow-up studies of patients post-mitral repair report excellent results using short term warfarin, and they also show that a third of patients discharged in sinus rhythm will have an episode of atrial fibrillation shortly after. In addition, the highest risk of thromboembolism occurs in the early months post surgery. Therefore, until studies demonstrate the safety of omitting warfarin for patients undergoing mitral valve repair, 3 months of anticoagulation should remain the standard of care.
Key Words: Thoracic surgery; Anticoagulation; Mitral valve repair; Warfarin
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1. Introduction
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A best evidence topic was constructed according to the structured protocol. This protocol is fully described in the ICVTS [1].
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2. Clinical scenario
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You are looking after a 55-year-old man with mitral regurgitation who underwent a mitral valve repair with a quadrangular P2 resection and an annuloplasty ring. He is in sinus rhythm and well. You had talked to him about warfarin in the context of a mitral replacement in case you could not repair the valve. However, he is now keen to eliminate any additional risk of stroke as his mother had a severe stroke 5 years ago. He says that he would like to take warfarin if there was any additional chance of preventing a stroke. You decide to review the literature to answer his question.
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3. Three-part question
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In patients who have undergone [mitral valve repair] does [warfarin] have any benefit in terms of [survival or reducing thromboembolic complications]?
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4. Search strategy
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Medline1966 to July 2006, Embase 1980 to July 2006 using the OVID interface. [mitral valve repair.mp OR mitral repair.mp OR annuloplasty.mp OR mitral ring.mp] AND [exp warfarin/OR warfarin.mp OR exp.anticoagulants/OR anticoagulation.mp OR exp coumarins/OR coumarin.mp].
This search was repeated in the Cochrane database of systematic reviews. The American College of Cardiology, AHA/ACCP, NICE, SIGN, European Society of Cardiology and the British Society for Haematology guidelines were also hand searched.
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5. Search outcome
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The search identified 63 papers on Medline and 64 papers on Embase in addition to the hand searched guidelines. Twelve papers gave the best evidence on this topic (Table 1).
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6. Comments
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The ACC/AHA 1998 guidelines for the management of patients with valvular heart disease do not provide recommendations for patients who have undergone a mitral valve repair [2,3] and neither do the ACCP guidelines of 2004 [4]. The European Society of Cardiology do provide guidelines for these patients, stating that there are no randomized controlled trials to support the safety of omitting warfarin after mitral repair. They recommend 3 months of warfarin at a target INR of 2.5 or 3.0 if there are additional risk factors. They acknowledge that this is based on expert consensus and acknowledge that many surgeons do not follow this guideline.
Vaughan et al. [5] in a survey of UK surgeons found that 64% of consultants used warfarin post-mitral repair, thus demonstrating that there is much variation in the anticoagulation management of patients post-mitral repair in the UK.
Of the large series of patients with mitral valve repair, Carpentier et al. [6,7] have provided the longest follow up. They reported their long-term results of 928 patients with rheumatic regurgitation and 162 patients with non-rheumatic regurgitation, with a follow up of up to 29 years. This group used 2 months of warfarin for all patients, and only 3 patients had a stroke in the first 3 months. There were 37 thromboembolic events in these patients and there was a very high association with atrial fibrillation.
Jovin et al. [8] reviewed 245 patients who underwent mitral repair. One hundred and eighty-one patients were discharged in sinus rhythm; 64 (36%) of these had an episode of atrial fibrillation (AF) during the postoperative period. Of the 180 patients who were in sinus rhythm at discharge, 98 (54%) were discharged on warfarin, 78 (43%) were discharged on aspirin and 3 (2%) received no anticoagulation or antithrombotic therapy at discharge. The authors recommended oral anticoagulation for 3 months, until the endothelialisation of the newly implanted prosthesis and suture material takes place.
Aramendi et al. [9] reported on the thromboembolic risk of 235 patients having replacements or repairs from 1990–1995. In total, six episodes of thrombo-embolism were reported. All occurred in the first postoperative year, four reported during the first three months follow up. Two patients were on ticlopidine and four episodes were in patients having warfarin. The risk of thromboembolism in the first three months of follow up analysed by hazard function showed the highest risk in the first month, but this rapidly declined thereafter.
Galloway et al. [10] reported on 148 patients after mitral valve reconstruction surgery. All patients were started on warfarin on the third postoperative day for 3 months. Six late thromboembolic complications were reported in five patients. Two patients were on warfarin during the event at 2.5 months and 13.2 months post surgery. Four episodes occurred when the patient was on aspirin at  1, 6.5, 15.6 and 16.3 months post surgery. One patient died from a stroke. Total freedom from late thromboemboli was 97.6% at 1 year and remained at 95.2% for years 2–7.
Deloche et al. [5] followed up 195 patients who underwent mitral repair. All patients were started on warfarin on the third postoperative day and discontinued after 3 months. Ten patients had a thromboembolic event, for an actuarial rate of 94% patients free of thromboembolism at 15 years (linearised rate of 0.4%/patient-year). Of the ten thromboembolic events, seven were TIAs without major sequelae, two patients had permanent deficit and one patient died. Eighty-eight patients remained on long-term anticoagulation because of AF. There were six reported haemorrhagic complications, for an actuarial rate of 95.6±1.97% patients free of anticoagulation related haemorrhage at 15 years for the total series and 91% for the 88 patients receiving anticoagulation.
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7. Clinical bottom line
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The current European Society of Cardiology guidelines support the use of warfarin for 3 months post-mitral repair, citing an absence of studies supporting the safety of omitting warfarin. They acknowledge that this is based on expert consensus and that many surgeons do not follow this guideline. The longest follow-up studies of patients post-mitral repair report excellent results using short term warfarin, and they also show that a third of patients discharged in sinus rhythm will have an episode of atrial fibrillation shortly after. In addition, the highest risk of thromboembolism occurs in the early months post surgery. Therefore, until studies demonstrate the safety of omitting warfarin for patients undergoing mitral valve repair 3 months of anticoagulation should remain the standard of care.
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References
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Abstract
1. Introduction