Mitral valve bio-prosthesis and annuloplasty thrombosis during extracorporeal membrane oxygenation: case series

Background

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a well-recognized form of haemodynamic support for patients with refractory cardiogenic shock, who are unable to be weaned off cardiopulmonary bypass. Thrombosis or bleeding from cannula sites or surgical wounds are the leading cause of morbidity and mortality in these patients, and presents a delicate balance of anticoagulation during management of patients undergoing circulatory support.

Case summary

In this case series, we discuss three cases of patients undergoing mitral valve replacements or repair with thrombosis of their new bio-prosthesis in the immediate post-operative setting. All three patients were supported with VA-ECMO post-operatively, and thrombosis occurred despite anticoagulation.

Discussion

During extracorporeal membrane oxygenation, the reduced flow throughout the heart increases the risk of intra-cardiac thrombosis. This is of particular importance in the context of mitral valve replacements and repairs, where the bio-prosthesis is an additional risk factor for thrombosis. Our cases demonstrate the morbidity and mortality of such complications, with the likely aetiology being low transvalvular flow in a newly inserted valve combined with the pro-thrombotic state created by the VA-ECMO circuit.

Management of oral anticoagulation in the surgical patient

New oral anticoagulants (NOACs) have recently emerged as an alternative for vitamin K antagonists and are now widely available. Although there is good evidence for their roles in the appropriate clinical settings, so far no reversal agent is currently available. Likewise, there is no readily available laboratory test to quantify drug levels but coagulation assays may provide qualitative information about the presence of some NOACs. We aim to review the current literature regarding the optimal management of oral anticoagulation in the perioperative setting.

New oral anticoagulants and perioperative management of anticoagulant/antiplatelet agents

BACKGROUND

The strategy of whether to continue anticoagulation and antiplatelet agents during surgery depends on an evaluation of the thromboembolic risk and haemorrhagic risk of the individual patients. Procedures that carry a significant risk of bleeding may require temporary cessation of the medication.

OBJECTIVE

We briefly review the use of common oral anticoagulant and antiplatelet agents, including clinical indications and limitations associated with those agents. We also discuss the risks of thromboembolism, and balancing bleeding risk in patients receiving oral anticoagulation therapy, temporary interruption of such therapy and management of such patients undergoing an elective surgical procedure.

DISCUSSION

Generally, patients at high risk of thromboembolism should be considered for a more aggressive perioperative management strategy with bridging therapy. Current recommendations for dual antiplatelet treatment range from 4 weeks in patients undergoing elective stenting with bare metal stents, up to 12 months in patients with drug-eluting stents or patients undergoing coronary stenting for acute coronary syndrome. If a patient is to undergo high-bleeding-risk surgery and an antiplatelet effect is not desired, clopidogrel, prasugrel and ticagrelor should be discontinued 5-7 days before the procedure. Early, effective communication between general practitioners and specialists is useful in managing high-risk patients on anticoagulation/antiplatelet agents during the perioperative periods.