ARTICLE IN BRIEF
A new evidence-based review offers guidance on the use of antithrombotic drugs before surgery and other invasive medical procedures in patients with ischemic cerebrovascular disease.
In the May 28 edition of Neurology, the Guideline Development Subcommittee of the AAN reviewed past research on the use of antithrombotic drugs before surgery and other invasive medical procedures in patients with ischemic cerebrovascular disease — even minor procedures like dental visits. The AAN guideline focused on weighing the risk of stroke when anticlotting drugs are stopped versus the risk of bleeding during a procedure if these medications are continued.
Why do the evidence review now? “Before this review, there were no guidelines for neurologists looking at whether these individuals should continue or stop the anticlotting drugs before having procedures,” said Melissa J. Armstrong, MD, assistant professor of neurology at the University of Maryland School of Medicine, who was the lead author on the review. “This question is often posed to neurologists by surgeons, dentists, and others performing procedures. It's important that neurologists and other clinicians know the evidence.”
In a telephone interview, Dr. Armstrong answered Neurology Today's questions about the Committee's review and recommendations.
WHAT ARE THE PROS AND CONS OF CONTINUING BLOOD THINNERS SUCH AS WARFARIN DURING PROCEDURES?
The reason to continue aspirin, warfarin, or other anticlotting drugs or blood thinners is to try to prevent another stroke in patients who have already had a stroke or to prevent a first stroke in patients with atrial fibrillation, an irregular heartbeat. We found evidence that patients who stop aspirin are at a higher risk of having a stroke than patients who continue it. We couldn't find good information to tell us if patients taking warfarin have a higher risk of stroke if they stop the warfarin, but we suspect this is the case.
The downside to continuing aspirin, warfarin, or other anticlotting drugs or blood thinners during procedures is that they increase the risk of bleeding. Major bleeding — bleeding that is hard to control, requiring another surgery, a blood transfusion, or causes other serious problems — is something all doctors and patients clearly want to avoid. If continuing these drugs doesn't worsen bleeding or only causes more minor bleeding, though, it is likely worth continuing the anticlotting drugs to prevent stroke. Bleeding was not considered important in this guideline if it was mild, simply required a doctor to hold pressure for longer, or was not linked to surgical problems.
WHAT WAS CHALLENGING ABOUT PUTTING TOGETHER THESE GUIDELINES?
Because every procedure has its own bleeding risks, we had to look for and then analyze research on any and every procedure we could find. This was a huge undertaking. Because we looked at so much data, the full guideline is only published online. Only a summary of our results fit in the print edition of Neurology.
WHAT ARE SOME OF THE IMPORTANT FINDINGS?
There is strong evidence [Level A] that in most situations, stroke patients should continue their aspirin or warfarin treatment when undergoing dental procedures. Aspirin or warfarin should probably be continued during skin procedures, too — [based on moderate evidence supporting a Level B recommendation] — as they are unlikely to increase important bleeding during skin procedures. Aspirin is also likely to be safe in some other minor procedures, described further in the guideline. It is important that stroke patients work closely with their doctors and care teams, though, to decide whether to temporarily stop or keep an anticlotting drug before a procedure.
HOW DO THE NEW GUIDELINES DIFFER FROM STANDARD PROCEDURES?
The challenge is that there are no standard procedures, at least not universally. Different doctors and patients make different decisions, even in very similar circumstances. This guideline helps summarize the evidence to help doctors and patients make more informed decisions. While information is available for many minor procedures, the guideline also points out that there are many procedures for which we don't know the best approach. [There is insufficient evidence, for example, to support or refute periprocedural heparin bridging therapy to reduce thromboembolic events in chronically anticoagulated patients. For more information, see the sidebar, “Bleeding Risks Associated with Continuing Antithrombotics with Various Procedures.”]
WHY NOT TEMPORARILY STOP THESE MEDICATIONS?
In some cases, temporarily stopping these medications is the best approach. Because these medicines are being used to prevent a stroke, though, stopping them could be associated with an increased risk of stroke. We know that stopping aspirin increases one's risk of stroke, but the data for warfarin are inconclusive. The absolute risk of having a stroke when stopping these medications is likely low in most situations, but if a stroke does occur, it can be devastating.
WHO ELSE SHOULD NEUROLOGISTS INFORM ABOUT THEIR PATIENTS' ANTITHROMBOTIC MEDICATION USE?
Deciding whether to continue or stop anticlotting drugs involves a team approach. The neurologist, surgeon/dentist, and patient all need to discuss the best approach, which is individualized from person to person. If patients are taking these medications for stroke and heart reasons, primary care physicians and/or heart specialists are also important to include.
WILL THERE BE A FOLLOW-UP STUDY TO SEE IF THESE GUIDELINES HAVE ANY IMPACT ON STROKE OCCURRENCE IN PATIENTS FOLLOWING SURGERY?
I hope someone will do that study! We recommend in the guideline that we need large registries of stroke patients undergoing surgery. These registries would record important details about stroke patients receiving anticlotting drugs, whether these drugs were stopped or continued, the type of procedure, and the outcomes — for example, whether the procedure was uneventful or complicated by stroke, other clotting problems, or bleeding. This would help us know more about the best approaches in the future.