HOW I DO – Preoperative/Preprocedure Antiplatelet or Anticoagulation Drugs PART – 7

HOW I DO – Preoperative/Preprocedure Antiplatelet or Anticoagulation Drugs PART – 7

(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)

Question: In last part, we covered some important points related to preoperative testing and surgical clearance. 1. Most important evaluation is HISTORY. Then CBC, PT, aPTT. If no history of excessive bleeding in past with procedures or dental extraction or injuries, and these tests are normal, then patient is very unlikely to have bleeding disorder. But if history of excess bleeding, then refer to hematologist even if CBC, PT, aPTT are normal. 2. BT CT have no role in modern medicine now. 3. BT cannot be used to study effect of antiplatelet agents. 4. Importance of good laboratory for these tests, and need for fresh sample. 5. If you are suspecting a bleeding disorder, you should alert your pathologist. To look for platelet morphology and number more carefully, in addition to other tests.

What other tests or issues our readers need to be aware of?

Answer: What to do when patient is on antiplatelet agents or anticoagulation?

What if any tests are abnormal, such as low platelet?

Let us discuss more common scenario first. Patient is on antiplatelet agent and needs a procedure, surgery.

1. Dental procedure, in general can be done without holding aspirin or similar antiplatelet agents.
2. For a major surgery, there is no consensus on how long to hold antiplatelet agents. Experts recommend anywhere between 48 hours to 7 days. With aspirin alone, most people are more comfortable with a shorter duration. With dual antiplatelet therapy i.e. aspirin and clopidogrel OR with newer antiplatelet agents like ticagrelor for example, longer duration is advisable.

What to do if a more urgent surgery is required e.g. trauma, acute cholecystitis or appendicitis? You explain higher risk to the patient. And depending on surgery, you can either give platelet transfusion prophylactically, OR keep platelets on stand by and use in case there is excess bleeding. Unlike anticoagulation related bleeding, antiplatelet agents related bleeding has wide variations.

Also, remember there is no test to measure effect of antiplatelet agents reliably e.g. bleeding time, platelet function tests. Antiplatelet agents do not reduce platelet number.

3. For ascitic tapping, bone marrow biopsy, pleural tapping, lumbar puncture, or similar level of procedure, there is no need to hold the antiplatelet agents or any extra intervention.

Que: Thank you so much for this clarity. Now what about if patient is on anticoagulation such as warfarin, acitrom, OR newer agents like apixaban or dabigatran or rivaroxaban.

Ans: Yes. These medicines pose a very high risk for bleeding related to procedure, and must be withheld before surgery or major dental work. And before most procedures too like lumbar puncture, BM biopsy, pleural tap etc.

Warfarin or Acitrom effect can be measured by PT. Heparin by aPTT. But NOAC, LMWH effect cannot be measured by routinely available tests. One has to be very careful. Basic tests like CBC, PT, aPTT will be normal for patients on these drugs and yet they are fully anticoagulated and will have serious bleeding with procedure. Hence history and careful evaluation of all medicines is extremely important. Not just blood tests. ONE VERY IMPORTANT POINT TO NOTE IS RELATED TO NAME OF THE DRUG. SO MANY MANY BRAND NAMES OF ABOVE NOTED AGENTS ARE AVAILABLE. PATIENTS MAY BE ON ONE OF THESE WITHOUT KNOWLEDGE THAT THIS DRUG IS ANTICOAGULATION OR ANTIPLATELET AGENT.

1. Dental work – cleaning is ok. But anything that requires injection of local anesthesia or more tissue cutting, requires holding anticoagulation.
2. How long to hold the drug depends on the half life of drug. For example, warfarin or acitrom requires about 5 days for its effect to completely go away. In 72 hours, there will be substantial reduction but may not get to normal level of PT. In case of urgency, it can be reversed using vitamin k, and FFP under supervision of a hematologist. Vitamin k alone is not sufficient as it’s effect will wear off in about 12 hours whereas warfarin is much longer acting. Means if you give say 30 mg vitamin k, you may have normalization of PT but this will take several hours i.e. 8-12 hours AND within next 8-12 hours or so, PT will rise again significantly. Hence you cannot rely on vitamin k alone.
3. NOAC like apixaban or dabigatran or rivaroxaban, need holding for about 24-48 hours before a major procedure. If more urgent, then you need to involve a hematologist. PT, aPTT cannot be used to measure the effect of these drugs. Since there is no good antidote that is routinely available. Vitamin K here is not effective. Some agents have antidote available for reversal in case of emergency.
4. Heparin or LMWH – same principles apply as NOAC. Vitamin k does not work. Need to hold regular (unfractionated) heparin for about 12 hours. And LMWH for about 24 hours. Protamine can be used to reverse regular heparin within minutes, as is done during CABG surgery. But protamine is not as effective for LMWH. There is no good antidote for LMWH. Also PT, aPTT cannot be used to measure effect of LMWH.

January 17^th , 2024 Dr Chirag A. Shah; M.D. Oncology/Hematology (USA), 9998084001. Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com   www.shyamhemoncclinic.com