Peri-Operative anticoagulation /antiplatelet therapy A Shift in Paradigm BMHGT04/29/09

Balancing Thromboembolic and Bleeding Risks in the Perioperative Period   Thromboembolic risks: (1)Disease specific thromboembolic risks when discontinuing warfarin or ASA )stents (2)Hypercoagulability associated with surgery.   Bleeding risks: (1) the patient (2) the use of anticoagulant/antiplatelet therapy (3) the surgery or procedure

Thromboembolic risk when discontinuing OAC

Bleeding Risks Patient:   Previous history of bleeding, especially with invasive procedures or trauma   Use of concomitant antiplatelet and nonsteroidal antiinflammatory medications. Procedure:   High :include major operations and procedures (lasting >45 minutes)   Low : include non-major operations and procedures (lasting <45 minutes) Perioperative anticoagulants:   2-day period : 2 to 4% for major surgery 0 to 2% for non-major surgery.

Warfarin   INR starts to fall at approximately 29 hours after the last dose of warfarin   A half-life of approximately 22 hours   It is reasonable to start bridging therapy approximately 60 hours after the last dose of warfarin.

Perioperative bridging algorithm   Low risk of ATE or VTE: No heparin bridging preoperatively and only prophylactic doses of LMWH or UFH postoperatively in conjunction with resumption of warfarin.

Low-molecular-weight-heparin (LMWH)   Allowed bridging therapy to be administered to outpatients.   Doses of LMWH that are recommended for treatment of venous thromboembolism are administered once or twice daily, generally for 3 days before surgery.   Required to determine whether the benefit of bridging therapy outweighs the associated risks of bleeding.

Unfractionated heparin (UFH) Advantage:   A short half-life(60 minutes)   easily reversed (by protamine sulfate)Disadvantage:   Intravenous administration necessitates hospitalization before surgery,   Inconvenient and expensive.

Perioperative bridging protocol Instructions regarding IV UFH use   1. Should start at least 2 days prior to surgery at therapeutic dose using a validated, aPTT-adjusted, weight-based nomogram (ie, 80 U/kg bolus dose IV followed by a maintenance dose of 18 U/kg/h IV)   2. Discontinue 6 hours prior to surgery   3. Restart no less than 12 hours postoperatively at the previous maintenance dose once hemostasis is achieved   4. Discontinue IV UFH when INR is in therapeutic range (1.9)

Perioperative bridging protocol Instructions regarding LMWH use:   1. Should start at least 2 days prior to surgery at BID therapeutic dose (ie, enoxaparin 1 mg/kg SC BID or dalteparin 100 IU/kg SQ BID)   2. Discontinue at least 12 hours prior to surgery (if surgery is in early A.M. consider holding previous evening dose)   3. Restart usual therapeutic dose within 12–24 hours after surgery once hemostasis is achieved   4. Discontinue LMWH when INR in therapeutic range (1.9)

Perioperative bridging protocol Instructions regarding warfarin use:   1. Stop warfarin at least 4 days prior to surgery   2. Check INR 1 day prior to surgery If 1.5, proceed with surgery If 1.5 to 1.8, consider low-level reversal with Vitamin K If 1.8, recommend reversal with Vitamin K (either 1 mg SC or 2.5 mg PO)   3. Recheck INR day of surgery   4. Restart maintenance dose of warfarin the evening of surgery   5. Daily INR until in therapeutic range (1.9)

Recommendations The Seventh American College of Chest Physician Consensus Conference:   Intermediate risk of thromboembolism － prophylactic (or higher) dose UFH or LMWH as perioperative bridging therapy   High risk of thromboembolism － full-dose UFH or LMWH   Low risk of bleeding － Continue warfarin therapy at a lower dose to maintain an INR of 1.3 to 1.5.

Orthopedic surgery in patients with coronary stents  Bare metal stents  Drug eluted stents (sirolimus/pacltaxel)  Dual antiplatelet therapy recommended for 12 months  Life long ASA in low bleeding risk pts  45% mortality on stopping ASA (without surgery)_-  Heparin does not prevent stent thrombosis

Current recommendations  Assess stent thrombosis risk  Defer surgery (bare metal one month; 12 month for drug eluted )  Do not stop ASA; use coumadin with ASA for VTE prophylaxis (never ASA alone) for VTE prophylaxis (never ASA alone)  Assess resources to revitalize thrombosed stent in hospital ( very high mortality)