35

QUESTION

EXPLAIN ALL OF THESE NEW ANTICOAGULANTS TO ME. SHOULD I CONSIDER STOPPING THEM PREOPERATIVELY?

Elizabeth Verner-Cole, MD
Phoebe Lin, MD, PhD

Both thromboembolic and retinal disease occur more frequently in older patients and, with an increasing aging population, retinal surgeons will face a growing number of patients on anticoagulants. Given the complexities of retinal surgery, often involving highly vascular tissue, it is important to determine whether or not it is safe to proceed with surgery in patients on anticoagulants. Developed in 1954, Coumadin (warfarin) continues to be the most prescribed anticoagulant to date. Its method of action is via Vitamin K inhibition, ultimately decreasing levels of clotting factors X, IX, VII, and II (thrombin) as well as proteins C and S. Due to its indirect action on the clotting cascade as well as its many drug-drug and food-drug interactions, it can be difficult to obtain optimal anticoagulation. Studies show that up to 50% of the time, patients on warfarin are not within their target international normalized ratio (INR) range (typically INR = 2 to 3) and are thus either under- or over-coagulated.¹ For this reason, many new oral anticoagulants have been developed that inhibit a single factor in the coagulation cascade, providing a more direct and pharmacologically reliable effect. Initially labeled novel oral anticoagulants, they are also known as non–Vitamin K antagonist oral anticoagulants (NOACs) or direct oral anticoagulants (DOACs). The Food and Drug Administration–approved DOAC agents include the thrombin inhibitor Pradaxa (dabigatran) and the factor Xa inhibitors Xarelto (rivaroxaban), Eliquis (apixaban), and Savaysa (edoxaban) (Table 35-1). DOAC agents offer multiple advantages over warfarin, including fewer food and drug interactions, no need for repeated blood testing, rapid onset within 2 to 3 hours (compared to 2 to 3 days with warfarin), and lower risk of intracranial hemorrhage. Disadvantages of DOAC agents include limited ability to quickly reverse the anticoagulation effect (only dabigatran has an approved reversal agent, idarucizumab), altered metabolism in patients with renal insufficiency or over 75 years old, and increased risk of gastrointestinal bleeding.²

While the safety of anticoagulant use during cataract surgery is well-established, the risk of continuing anticoagulation at the time of retinal surgery has not been tested extensively, particularly with DOAC agents. Table 35-2 lists the studies to date of retinal surgery performed in patients on anticoagulants including the DOAC agents. The rate of visually significant postoperative hemorrhage (vitreous, retinal, or choroidal) across the majority of these studies ranges from 10% to 13%, with most cases occurring in proliferative diabetic retinopathy.^3–13 This is comparable to the rate of postoperative hemorrhage seen in patients not on anticoagulants undergoing vitrectomy for diabetic retinopathy. In fact, 2 studies that were conducted to compare rates of vitreous hemorrhage after vitrectomy for diabetic retinopathy with and without bevacizumab showed a rate of recurrent vitreous hemorrhage as high as 27% without the use of preoperative bevacizumab.^14,15 The latter studies, however, did not control for patients on anticoagulation.

Shieh and colleagues¹⁶ investigated overall ocular complications occurring in patients anticoagulated with DOACs, including patients who had complications associated with ocular surgery and patients who had not received recent ocular surgery. They reported one spontaneous submacular hemorrhage in a patient on apixiban with intermediate non-neovascular age-related macular degeneration. They also reported 2 patients on dabigatran, one of whom developed multiple recurrences of hyphema after Ahmed tube surgery for neovascular glaucoma in the setting of an ischemic retinal vein occlusion until switching to warfarin, after which the hyphema resolved. Despite a second patient stopping dabigatran 72 hours before surgery, he developed a hyphema and vitreous hemorrhage after pars plana vitrectomy, removal of an intraocular lens implant with placement of an anterior chamber lens, and this cleared on discontinuation of this DOAC, but then he had recurrent intraocular hemorrhage after restarting dabigatran. A repeat vitrectomy was necessary, and dabigatran was stopped, without further ocular complication. Shieh et al also reported 3 patients on rivaroxaban, one of whom had a spontaneous rhegmatogenous retinal detachment with massive subretinal hemorrhage and vitreous hemorrhage and who was switched to warfarin after repair without further complication. A second patient on rivaroxaban developed a spontaneous vitreous hemorrhage that resolved on its own and was not associated with retinal breaks or other retinal pathology. A third patient on rivaroxaban developed massive hemorrhagic conjunctival chemosis, hyphema, and vitreous hemorrhage, as well as hemorrhage of the eyelids and cheek after vitrectomy surgery to remove a lens fragment even though a subtenon rather than retrobulbar block was used.¹⁶ In large non-inferiority trials comparing dabigatran to warfarin, ocular hemorrhage occurred but was considered minor and not vision-threatening.^17,18 However, there exists one case report of bilateral spontaneous choroidal hemorrhage, vitreous hemorrhage, and hyphema occurring with this agent.¹⁹ Phase III clinical trials for the other DOAC agents have not reported consistent ocular complications.^20,21 The authors have an unpublished case of a postoperative suprachoroidal hemorrhage and hyphema occurring in a patient on apixiban who required a vitrectomy for a dislocated iris-sutured intraocular lens implant, who did not have this complication with 2 prior vitrectomies 10 years earlier, when she was on warfarin instead. A recent meta-analysis comparing DOACs and traditional anti-thrombotic drugs for bleeding complications found no significant difference in intraocular bleeding complications.²²

Table 35-2

Studies Investigating Anticoagulation in Vitreoretinal Surgery

ASA = aspirin; VH = vitreous hemorrhage

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. 15 How Soon Should a Patient With Floaters Be Examined and How Should I Manage a Patient With an Acute Posterior Vitreous Detachment?
2. 34 Should I Send a Patient With a Large Chronic Macular Hole to a Retina Doctor? Do They Even Operate on Those?
3. 38 Why Should I Send My Retinal Degeneration Patients to Specialists if There Is No Cure for Their Condition?
4. 21 How Do I Distinguish One Pigmented Lesion From Another?

Stay updated, free articles. Join our Telegram channel

Join