Stopping Antithrombotics for Surgery: Risk Assessment vs. “Clearance”

We’re often asked to “clear” patients for various surgeries, and specifically to countenance the surgeon or dentist’s recommendation to discontinue antithrombotics perioperatively. There are several issues embedded in these requests, and an important conceptual confusion that I’d like to address.

The first pair of questions is straightforward (although the answer isn’t): “What is the risk of stroke if the patient stops aspirin/clopidogrel/warfarin prior to surgery? What is the risk of bleeding if these drugs are continued?” Unfortunately, we don’t have conclusive evidence to guide us, but the AAN just published a much-needed guideline on this topic. The take-home points are:

  • Stopping antithrombotics is associated with an increased risk of thromboembolic event.
  • For many procedures, specifically dental procedures, continuing antithrombotics is very unlikely to result in clinically important bleeding.
  • For many other procedures we don’t have good data on the bleeding risk.
  • There does appear to be elevated bleeding risk during hip replacement surgery.

This guideline should help us make the argument that many times, antithrombotics do not necessarily need to be held perioperatively.

The confusion arises when the surgeon asks the neurologist to “clear” the patient for surgery. I see our role as providing to the patient and surgeon a risk assessment. We might judge the risk of stopping aspirin, or the risk of perioperative neurological complication more generally, to be high or low. The surgeon might judge the bleeding risk to be high or low. The neurologist, surgeon, and patient need to discuss these and make a risk/benefit determination, and the patient should be afforded the chance to express how much risk he’s willing to take and how beneficial he feels the proposed intervention will be to his quality of life. What we neurologists don’t do is “clear” the patient for surgery. Only the patient or his surrogate can consent to surgery and only the surgeon can agree to proceed with surgery. It’s not the neurologist’s decision.

What sometimes happens, however, is that the surgeon states that he’ll only operate if the neurologist “clears” the patient, which I infer to mean “judge to be low risk”. If we judge the risk to be high, the patient sometimes calls our clinic asking for a revised opinion because he really wants his tooth extraction, back surgery, whatever. The conceptual problem here is that a risk determination is conflated with a treatment decision, when these are very different. The neurologist might judge the risk to be high, but the patient might be in so much pain that he’s willing to accept a high risk of stroke in order to obtain relief. Proceeding with surgery might then be appropriate, but that decision is one between patient and surgeon.

This conceptual confusion comes up in many other contexts. I’m reminded of a time when I was a post-sophomore fellow in pathology. We read a biopsy as showing cellular pleomorphism and nuclear atypia, but we could not conclusively declare the specimen as showing malignancy. The surgeon strongly urged us to judge the specimen otherwise, relying on his observations in the OR, the interpretation of the patient’s imaging studies, etc. “I just know this patient has cancer,” he stated. Our response was, “If you know your patient has cancer, then treat him for cancer. But we can’t say that there’s cancer in this particular specimen.” Again, the determination of what the biopsy showed was conflated with a decision on how to treat the patient.

Here’s another example: During my stroke fellowship, I did a few stints on the general consult service and saw an unfortunate patient with anoxic brain injury. The question posed was whether he met neurological criteria for death, thus allowing the transplant team to harvest his organs. Exam showed the patient to have suffered devastating cerebral and brainstem injury, but the AAN criteria for “brain death” were not strictly satisfied–the body temperature was too low, or the electrolytes were off–I forget exactly. The transplant coordinator was infuriated. I was puzzled by this, since the AAN criteria are quite specific–either the patient meets them or he does not. When she argued further on the basis of the patient’s obviously devastating illness, the benefit that the organs would provide to others, etc., I gently suggested that if she and her team were convinced of those things, maybe they should proceed with organ harvest irrespective of my findings. This infuriated her even more: “How could you ever suggest such a thing?! That would be totally wrong!”

Now, I would never actually recommend breaking the law in this way, but the case brings up, among several other issues about brain death that I won’t get into here, this recurrent issue of confusing the clinical assessment with a treatment decision. These types of assessments stand on their own–they don’t vary according to how badly the patient wants surgery, how convinced a doctor is that his patient has cancer, or how just it would be to transplant a dying patient’s organs into another. What the treating physicians do with the assessment is another matter, but the two shouldn’t be confused.


About Justin A. Sattin

I'm a vascular neurologist and residency program director. I created this blog in order to share some thoughts with my resident and other colleagues, and to foster my own learning as well.
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One Response to Stopping Antithrombotics for Surgery: Risk Assessment vs. “Clearance”

  1. Khalid says:

    Exactly ….. We should make it clear that ” we cannot clear any body for having any thing !! ” because this is getting more and more common in our consult service , when they some times ask to clear the patient for having a surgery even without asking about anti-thrombotics, just because he has a carotid disease for example.

    i just want to refer to the cardiology literature, as always most of the time we follow then in our stroke literature, but they have more strict guideline regarding peri-operative risk assessment, but despite that they would never use the word ” clear” but they state usually a number representing the likely risk of peri-operative cardiac event, because there will always be a risk even if that risk is low in optimal surgery, that risk might be double or 5 times if any complication happened during the operation. so this is really important for documenting our consult notes.

    also, when we are asked about peri-operative stroke risk, we know that there will be higher risk with stopping anti-thrombotics, but we should also be conscious that its not only anti-thrombotics alone playing a role in that game. for example, if we don’t know what is the degree of carotid stenosis the patient has, and with induction of GA, there is a theoretical risk of border zone stroke, same if the patient gets atrial arrhythmia or A.fib during cardiac surgery for example which will put him at risk of stroke , regardless of anti-thrombotics.

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