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Surgery
aspirin in the Clopidogrel in Unstable angina to prevent Recurrent buckling and external drainage procedure. They concluded that
ischemic Events (CURE) trial,
10
the Clopidogrel as Adjunctive successful visual and anatomical results may be achieved after VR
Reperfusion Therapy (CLARITY)
11
trial and Clopidogrel and Metoprolol in surgery for patients receiving anticoagulation with warfarin without
Myocardial Infarction Trial (COMMIT),
12
dual oral antiplatelet therapy cessation of therapy.
provided significant benefits in patients across the spectrum of acute
coronary syndromes (ACS). Dual antiplatelet therapy is also In both the Minimally Classic/Occult Trial of the Anti-Vascular
recommended in patients undergoing intracoronary artery stenting to endothelial growth factor (VEGF) Antibody Ranibizumab in the
prevent the potentially devastating complications of stent thrombosis, Treatment of Neovascular AMD (MARINA) and Anti-VEGF Antibody for
especially for drug-eluting stents (DES), where treatment is the Treatment of Predominantly Classic Choroidal Neovascularization
recommended for 12 months.
13
in AMD (ANCHOR) phase III trials, anticoagulation was not stopped.
Over two years, no ocular bleeding diathesis was encountered in an
Evidence for Continuation or overall average total of 1,852 intravitreal ranibizumab injections given
Cessation of Antithrombotic Therapy to 105 subjects on warfarin. This suggests that an intraocular injection
in Vitreoretinal Surgery in a patient on warfarin is unlikely to cause ocular haemorrhage.
20
Although there was some controversy in earlier series as to
whether warfarin and aspirin increase the risk of haemorrhage in There have been small case series suggesting that aspirin and
intraocular surgery,
14
there was no compelling evidence to support clopidogrel in combination can result in an increased bleeding
the cessation of anticoagulation prior to surgery.
15–17
In fact, recent tendency.
21–23
Flaxel
21
reported a case of suprachoroidal haemorrhage,
evidence suggests that it is safe to continue anticoagulation during vitreous haemorrhage and hyphaema resulting from complicated
VR procedures.
18,19
cataract extraction requiring anterior vitrectomy and iridectomy. Herbert
et al.
22
described a series of four patients on combination of clopidogrel
Narendran and Williamson
14
examined a series of 541 consecutive and aspirin or non-steroidal anti-inflammatory agents (NSAIDs) three of
patients undergoing VR surgery, 60 of whom were on aspirin and whom developed spontaneous vitreous haemorrhage requiring surgery
seven of whom were on warfarin. One of 11 choroidal and one developed persistent haemorrhage and redetachment
haemorrhages was on warfarin and one of nine rebleeds for diabetic following vitrectomy and retinectomy.
vitrectomy was on warfarin. They concluded that aspirin has no
effect on bleeding, but warfarin was associated with bleeding Kallio et al.
24
studied the risk of haemorrhagic complications related to
complications, so it is recommended that warfarin be stopped if the ocular anaesthesia. In a series of 1,383 patients undergoing
patient’s risk profile is low. intraocular surgery, 76 patients were receiving warfarin. This study
showed no predispostion to haemorrhage with either retrobulbar or
In a series of 50 ophthalmic procedures, McCormack
15
et al. found no peri-bulbar anaesthesia.
significant ocular haemorrhagic complications in the eight patients
undergoing VR surgery and recommended that surgery can be safely Risk of Stopping Antithrombotic Therapy
performed while the patient is therapeutically anticoagulated. Saitoh In a survey by Stone et al.
25
of 100 cataract surgeons who
et al.
16
described four patients undergoing vitrectomy and three discontinued warfarin treatment before cataract surgery, six
undergoing scleral buckling in a large series of anterior segment patients had acute strokes, two of which led to death, in addition to
surgery. They concluded that discontinuing anticoagulation was one patient who had a DVT and another who had a pulmonary
unnecessary for patients with life-threatening conditions. Gainey et embolus. In a survey of 57 physicians who discontinued
al.
17
reviewed 50 patients undergoing ocular surgery on warfarin anticoagulant therapy in the pre-operative period, Kapusta and
therapy, six of whom had VR surgery, and found no significant Lopez
26
found that one patient had a stroke and eight others had
difference in haemorrhagic complications among patients in whom peripheral thrombosis. In a survey of 504 members of the American
warfarin was continued and those in who it was discontinued. College of Mohs Micrographic Surgery and Cutaneous Oncology, 168
responding physicians reported 46 patients who experienced
Dayani et al.
18
reviewed 1,737 consecutive patients undergoing pars thrombotic events when their aspirin or warfarin therapy was peri-
plana vitrectomy (PPV) and selected 54 patients undergoing 57 operatively withheld, with 54% experiencing the event when
procedures while on warfarin therapy; they found no introperative warfarin was withheld and 39% when aspirin was discontinued.
haemorrhagic complications. Four eyes (7%) experienced post- Thrombotic events included 24 strokes, three cerebral emboli, five
operative haemorrhage that resolved spontaneously without MIs, eight transient ischaemic attacks (TIAs), three DVTs, two
visual sequelae or need for supplemental surgery. Two of these eyes pulmonary emboli and one retinal artery occlusion leading to
were in the subtherapeutic group (INR 1.2–1.49) and two were in the blindness. Three deaths were reported.
27
Several other series have
high therapeutic group (INR 2.5), with three of the four patients also reported life-threatening thromboembolic events that have
having vitrectomy for proliferative diabetic retinopathy (PDR) with been related temporally to the peri-operative discontinuation of
vitreous haemorrhage. They suggested that patients may safely both aspirin and warfarin.
28–31
undergo VR procedures while maintaining their therapeutic levels
of anticoagulation. Cessation of oral anticoagulation has been noted to cause a
paradoxical state of hypercoagulability secondary to rebound
Fu et al.
19
reviewed 25 patients receiving warfarin with INR ranging effect, postulated to be related to interruption of the equilibrium
from 1.5 to 3.1 while undergoing VR procedures. No intraoperative between vitamin-K-dependent factors and proteins C and S.
32–34
complication occurred apart from one patient who had an Similarly, the surgical milieu has been found to induce a
intraoperative subretinal haemorrhage associated with scleral hypercoagulable state including increased levels of plasminogen-
46 EUROPEAN OPHTHALMIC REVIEW