A new guideline has been made available from the American Academy of Neurology on the difficult issue of whether to stop antithrombotic medication during surgery or other medical procedures.

The guideline, published in the May 28 issue of Neurology, was developed by a team led by Melissa Armstrong, MD, University of Maryland School of Medicine, Baltimore.

“We cast a broad net to find any possible article on discontinuing antithrombotic medication before an interventional procedure,” Dr. Armstrong commented to Medscape Medical News. “Most of the research has been done in patients undergoing minor procedures such as dental and dermatological procedures. And I think we can say in most minor procedures you probably don’t need to stop aspirin. This may also be the case for warfarin, but we have fewer studies available so the recommendation must be more cautious with warfarin.”

In terms of major procedures, Dr. Armstrong noted that there is little evidence on either drug. “At present, most physicians would stop both agents. But our research suggests it may be safe to continue aspirin in most situations except hip surgery.”

The guideline itself lists all the procedures for which there are data on stopping or continuing aspirin or warfarin and gives recommendations with levels of evidence used to make those recommendations. There is little information on other agents because few studies have been conducted.

Dr. Armstrong commented: “We can’t assume the recommendations for aspirin can be extrapolated to other antiplatelet drugs, or those for warfarin can be applied to other anticoagulants. Each drug works differently.”

No Information on New Oral Anticoagulants

The guideline team couldn’t find any information on this issue with the new oral anticoagulants. “It is very important to do studies with these new drugs. They work differently to warfarin so we cannot assume they will require the same advice on stopping for procedures. They have a shorter half-life so it is possible that they can be used closer to surgery. But we need a lot more research on this,” Dr. Armstrong said.

This is the first time such guidelines have been issued by the American Academy of Neurology. Dr. Armstrong pointed out that similar guidelines have been developed by the American College of Chest Physicians (published in Chest in February 2012). “These were focused more on the cardiology perspective, whereas we focused on patients at risk of stroke, but the two guidelines generally came to broadly similar conclusions.”

She noted that no studies looked at both stroke and bleeding risk in patients continuing or stopping antithrombotics. “So we had to divide our findings into 2 parts: 1) stroke risk on stopping antithrombotic therapy, and 2) bleeding risk on continuing treatment. The clinician will have to apply both sets of findings to individual patients.”

The guideline team found an increased risk of bleeding with aspirin only in hip surgery (moderate evidence), and with warfarin in colonoscopy procedures (weak evidence). However, there was no information on warfarin in hip surgery but because it is thought to be a stronger antithrombotic than aspirin, the risk of bleeding is generally higher and it would not normally be used in this situation, Dr. Armstrong explained.

She added: “These studies are generally done by surgeons, and most surgeons would be reluctant to design a study which allowed warfarin to be used during any type of major surgery. The default mode is to stop warfarin during surgery in most circumstances.”

Balancing the Risk and Benefits

She explained that they are trying to weigh up the risk of 2 different events with quite different consequences.

“A stroke is an uncommon event but has devastating consequences, whereas a bleed is more common but generally has milder consequences. Surgeons are more concerned about bleeding risk during their procedure, and neurologists are more focused on preventing strokes, so we probably have different agendas. But it is important that we come together as a team to balance these requirements.”

Dr. Armstrong concluded, “This guideline tells us that aspirin appears safe to continue in a number of minor procedures. And we need more studies to look at aspirin in major procedures. For warfarin, we have less information, and we need more studies in minor procedures before thinking about major procedures.”

Neurology. 2013;80:2065-2069. Abstract