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Letters to the Editor

Antiplatelet therapy after bioprosthetic aortic valve replacement is unnecessary in patients without thromboembolic risk

Department of Cardiothoracic Surgery, St George's Hospital, Blackshaw Road, London SW17 0QT, UK

Received 13 September 2007; accepted 20 September 2007.

^_* Corresponding author. Tel.: +44 208 725 1079. (Email: justin.nowell{at}stgeorges.nhs.uk).

Key Words: Anticoagulation • Antithrombotic • Valve • Thromboembolism

We read with interest the article titled ‘Antiplatelet therapy early after bioprosthetic aortic valve replacement is unnecessary in patients without thromboembolic risk factors’ [1]. The authors conducted a retrospective non-randomised observational study to examine antiplatelet therapy after bioprosthetic aortic valve replacement in 288 patients without thromboembolic risk factors. They conclude that there is no apparent benefit to early antiplatelet therapy in this cohort of patients.

We concur with the authors that guidelines are confusing and the evidence is weak. We have recently reviewed the literature on antithrombotic therapy following bioprosthetic aortic valve replacement [2]. There are only two prospective randomised trials comparing an antiplatelet agent with a vitamin K antagonist [3,4] and both showed equivalence.

The incidence of thromboembolism following bioprosthetic AVR is between 0.9% and 2.2% per patient year. For an event rate of 2% and a risk ratio of 1.2, approximately 28,000 patients will be required and for a risk ratio of 2.0, 1527 patients will be required to identify a significant difference between the groups. Therefore, it is not surprising that Brueck and colleagues did not find a reduction in cerebral thromboembolism comparing their groups over a 12-month period.

We agree that a three-arm trial comparing aspirin, warfarin and no antithrombotic treatment is desirable. However, our own survey of UK cardiothoracic consultants showed that most were in favour of a two-arm trial. Surgeons appeared reluctant to offer no treatment since there are no guidelines advocating this approach.

Similarly, there are no studies specifically examining the safety of omitting warfarin and for this reason guidelines remain weighted in favour of early anticoagulation, albeit for 3 months. There are also no studies supporting aspirin therapy to prevent pannus formation. Therefore, it is timely to carry out a randomised controlled trial of patients undergoing tissue aortic valve replacement, comparing warfarin, aspirin and no treatment.

Footnotes

^\#9734; The author of the paper concerned was invited to reply to this LTTE but feels a reply is not necessary.

References

1. Brueck M, Kramer W, Vogt P, Steinert N, Roth P, Gorlach G, Schonburg M, Heidt MC. Antiplatelet therapy early after bioprosthetic aortic valve replacement is unnecessary in patients without thromboembolic risk factors. Eur J Cardiothorac Surg 2007;32:108-112.[Abstract/Free Full Text]
2. Nowell J, Wilton E, Markus H, Jahangiri M. Antithrombotic therapy following bioprosthetic aortic valve replacement. Eur J Cardiothorac Surg 2007;31:578-585.[Abstract/Free Full Text]
3. Aramendi JI, Mestres CA, Martinez-Leon J, Campos V, Munoz G, Navas C. Triflusal versus oral anticoagulation for primary prevention of thromboembolism after bioprosthetic valve replacement (trac): prospective, randomized, co-operative trial. Eur J Cardiothorac Surg 2005;27:854-860.[Abstract/Free Full Text]
4. Gherli T, Colli A, Fragnito C, Nicolini F, Borrello B, Saccani S, D’Amico R, Beghi C. Comparing warfarin with aspirin after biological aortic valve replacement: a prospective study. Circulation 2004;110:496-500.[Abstract/Free Full Text]

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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Justin Nowell Marjan Jahangiri Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nowell, J. Articles by Jahangiri, M. Search for Related Content PubMed PubMed Citation Articles by Nowell, J. Articles by Jahangiri, M. Related Collections Valve disease