Perioperative Antiplatelet Therapy

1. Precautions
   1. Aspirin is lifelong therapy that should not be interrupted for surgery following stroke, Acute Coronary Syndrome, or coronary revascularization
      1. This is regardless of time since vascular event or procedure
   2. Clopidogrel (Plavix) in combination with Aspirin should be continued at least until endothelialization of the stent or lesion can reasonably be expected
      1. For Drug-eluting Stents this duration is for a minimum of 1 year and may extend 2-3 years especially in high risk patients (see below)
2. Physiology: Antiplatelet agents and bleeding risk
   1. Plavix, Aspirin poison platelets for full 21 day life
   2. Agents stopped 7 days before surgery allows 33% of platelets to regenerate (50,000)
   3. Adequate platelet aggregation returns within 5 days of stopping antiplatelet agents
3. Physiology: Stent and coronary lesion endothelialization
   1. Stents and coronary lesions act as unstable Plaque until fully covered by a cellular layer
      1. Bare metal stents are completely covered by smooth muscle within 6 weeks and by endothelium within 3 months
      2. Drug eluting stents require 1-3 years for endothelialization
      3. Stent thrombosis is a catastrophic event (up to 45% mortality)
4. Physiology: Antiplatelet agent cessation and thrombosis risk
   1. Aspirin cessation: 3.1 Odds Ratio of cardiac complication (peak at 10 days)
   2. Aspirin cessation after coronary stent: 90 Odds Ratio
      1. Even 2 years after Drug-eluting Stent placement, Aspirin cessation may result in stent stenosis
   3. Clopidogrel cessation after drug eluting stent: Up to 57 Odds Ratio in first 18 months
   4. Risk of stent closure increases in the perioperative period due to increased platelet aggregation activity
5. Evaluation: Surgical Bleeding Risk
   1. Low surgical bleeding risk (transfusion not required)
      1. Minor otolaryngology surgery
      2. Minor orthopedic surgery
      3. Endoscopy without biopsy
      4. Anterior chamber eye surgery
      5. Dentistry
   2. Intermediate surgical bleeding risk (transfusion may be required)
      1. Visceral surgery
      2. Vascular surgery
      3. Major otolaryngology surgery
      4. Major orthopedic surgery
      5. Endoscopy with biopsy
   3. High surgical bleeding risk (transfusion required)
      1. Cardiac surgery
      2. Surgery with massive bleeding
      3. Surgery in a closed space
         1. Intracranial surgery
         2. Intramedullary canal
         3. Posterior eye chamber
6. Evaluation: Cardiac Risk for perioperative events in known coronary disease
   1. Low Cardiac Risk
      1. Bare metal stents, Angioplasty, or CABG >3 months prior
      2. Acute Coronary Syndrome >6 months prior
      3. Drug-eluting Stent >12 months prior
   2. Intermediate Cardiac Risk
      1. Bare metal stents, Angioplasty, or CABG 6 weeks to 3 months prior
      2. Acute Coronary Syndrome 6 weeks to 6 months prior
      3. High Risk Drug-eluting Stent >12 months prior
         1. Stent in dominant, proximal, ostial or bifurcated position or
         2. High risk patient with advanced age, Diabetes Mellitus, low ejection fraction or Renal Failure
   3. High Cardiac Risk
      1. Bare metal stents, Angioplasty, or CABG, Acute Coronary Syndrom <6 weeks prior (<3 months if complications)
      2. Drug-eluting Stent <12 months prior (longer if high risk drug eluting stent)
7. Protocol
   1. Low to Intermediate surgical bleeding risk
      1. Low Cardiac Risk
         1. Continue Aspirin OR Clopidogrel (Plavix)
      2. Intermediate Cardiac Risk
         1. Continue Aspirin AND, if prescribed, Clopidogrel (Plavix)
         2. Consider postponing elective surgery if intermediate surgical bleeding risk
      3. High Cardiac Risk
         1. Elective surgery: Postpone
         2. Urgent surgery: Perform surgery while continuing Aspirin AND Clopidogrel (Plavix)
   2. High surgical bleeding risk
      1. Low Cardiac Risk
         1. Stop Aspirin and Clopidogrel (Plavix) if necessary 5 days prior to surgery
         2. Restart antiplatelet medications within 24 hours after surgery
      2. Intermediate Cardiac Risk
         1. Postpone elective surgery
         2. Continue Aspirin
         3. Stop Clopidogrel (Plavix) 5 days prior to surgery and restart within 24 hours after surgery
      3. High Cardiac Risk
         1. Postpone elective surgery
         2. Perform only the most urgent procedures
         3. Continue Aspirin
         4. Stop Clopidogrel (Plavix) 5 days prior to surgery
            1. Consider replacing with Glycoprotein IIB/IIIA Inhibitors starting 3-5 days before surgery (anecdotal evidence)
8. References
   1. Chassot (2007) Br J Anaesth 99(3):316-28
   2. Chassot (2010) Am Fam Physician 82(12): 1484-9
   3. Douketis (2008) Chest 133(6):299S-339S
   4. (2009) Anesthesiology 110(1):22-3