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Peri-operative Management of Antithrombotic Therapy in Vitreoretinal Surgery
activator inhibitor 1.
35,36
Therefore, the necessity of stopping Period of Treatment and Timing of Surgery
anticoagulation for surgery with an inherently low haemorrhagic The European Society of Cardiology (ESC) guidelines
37
recommend
risk is questionable. against the temporary interruption of dual antiplatelet therapy (aspirin
and clopidogrel) within the first 12 months after the initial acute
Recent reports have shown that in patients with CAD, premature coronary ischaemic episode, and discourages prolonged withdrawal
withdrawal of antiplatelet agents may lead to an increased rate of of either aspirin or clopidogrel or both unless clinically indicated. In
recurrence of events. Interruption of dual-platelet therapy soon after stable patients who have undergone stent placements, clopidogrel
stent implantation increases the risk of acute stent thrombosis, with should be continued for three to four weeks after bare-metal stents
mortality varying from 15 to 45% in the first month. In addition, (BMS) and for six to 12 months after DES. If interruption of antiplatelet
interruption of antiplatelet agents long after implantation of DES may therapy becomes mandatory, such as in brain or spinal surgery, no
expose the patients to late stent thrombosis. Similarly, interruption of alternative therapy with proven efficacy can be proposed as a
dual antiplatelet treatment soon after the acute phase of non-ST substitute. In cases of elective VR surgery, it may be an option to
elevation acute coronary syndromes (NSTE-ACS) may expose patients postpone surgery until the critical period of treatment has been
to a high risk of recurrent events, even in non-stented patients.
37
completed to avoid premature interruption of dual therapy.
40
There have even been case reports, albeit few, resulting in death from
stent thrombosis shortly after interruption of combined therapy for Communication
elective surgery.
38,39
The decision for continuation or cessation of warfarin or antiplatelets
must be clearly communicated to the patient, his or her physician and
Important Considerations other staff involved in the care of the patient. Often, when they are
Risk of Haemorrhagic Complications unclear on the surgeon’s preference, patients may take the initiative
The majority of VR procedures can be safely performed without to stop or be advised to stop antithrombotic therapy pre-operatively
altering the patient’s antithrombotic regime. However, in cases of even when this is not requested by the surgeon. If the surgeon
complex delaminations, surgery to vascular lesions, scleral buckling initiates the cessation of warfarin or antiplatelet therapy, it is
or external drainage procedures, some surgeons may still prefer to imperative to ensure that the patient knows when to re-start
modify warfarin or antiplatelet therapy. It is important in the history- treatment post-operatively to avoid undue delay. Given the systemic
taking to elicit concomitant usage of over-the-counter medications risks, this is a point that no-one can afford to overlook.
such as NSAIDs for analgesia or herbal remedies, which may
potentiate the blood-thinning effects of prescribed medications, The Future
causing increased bleeding tendencies.
22
With the advent of newer surgical techniques such as 23 and 25G
transconjunctival sutureless vitrectomies, topical anaesthesia and
Thromboembolic Risk Profile intravitreal anti-VEGF as pre-operative adjunct in complex diabetic
The indications for antithrombotic therapy and the patient risk delamination and vitrectomy procedures, potential haemorrhagic
profile must be carefully assessed before initiating modification of risks associated with VR surgery are further decreased, allowing an
treatment regimes. For low-risk patients, such as non-valvular AF, equally favourable surgical outcome without cessation of medically
DVT after three months without risk factors or cardiomyopathy necessary anticoagulation or antiplatelet therapy. However, novel oral
without AF, stopping warfarin for several days prior to surgery to anticoagulants such as direct thrombin
41
or factor Xa inhibitors
42
and
decrease the INR to low therapeutic levels may be acceptable. In more potent antiplatelet agents
43
currently in development may pose
high-risk patients, such as those with hypercoagulable states, a new challenge.
mechanical valves or AF with history of recent thromboembolic
events who cannot afford to have their INR fall below a therapeutic Conclusion
range of 2.5–3.5, bridging therapy with IV heparin or LMWH may be Current evidence provides a compelling argument for maintenance of
necessary. Patients requiring IV heparin will need to be pre- anticoagulation and antiplatelet therapy during VR surgery. If required in
operatively admitted for close monitoring of the activated partial selected cases, modification of anticoagulation or antiplatelet therapy
thromboplastin time (APTT) and INR level and post-operatively must be undertaken in conjunction with the patient’s physician to allow
during re-initiation of anticoagulation. This is often a complicated full comprehension of the systemic thromboembolic risks and ensure
process and may prove difficult in the setting of day case VR surgery. safe peri-operative management of antithrombotic therapy. n
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EUROPEAN OPHTHALMIC REVIEW 47
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