Perioperative Management of Chronic Anticoagulation

1. Perioperative Management of Chronic Anticoagulation Henry Niho, M.D. Hospitalist David Geffen School of Medicine

2. Chronic Anticoagulation Warfarin (Coumadin) Well established role in multiple cardiovascular disorders Indications Atrial Fibrillation Mechanical prosthetic valves Thromboembolic disease

3. Chronic Anticoagulation:The Problem� The Problem in the peri-operative period Risks of full anticoagulation Increased risk of bleeding with surgical procedures Risks of interrupting anticoagulation Increased risk of thromboembolism

4. Chronic Anticoagulation:�Or is it? No difference in blood loss between patients who were and were not anticoagulated in one series of patients undergoing cholecystectomy or gastric resection Rustad, H, Myhre, E. Surgery during anticoagulant treatment. Acta Med Scand 1963; 173:115.

5. Chronic Anticoagulation:�Or is it? Anticoagulation maintained within the therapeutic range is safe in patients undergoing dental extraction McIntyre, H. Management during dental surgery of patients on anticoagulants. Lancet 1966; 2:99. Wahl MJ. Dental surgery in anticoagulated patients. Arch Intern Med 1998 Aug 10-24;158(15):1610-6.

6. Chronic Anticoagulation:�Or is it? Significant perioperative bleeding has been reported in various noncardiac operations in patients with prosthetic valves when anticoagulation was maintained Katholi RE, et al. Living with prosthetic heart valves. Subsequent noncardiac operations and the risk of thromboembolism or hemorrhage. Am Heart J 1976 Aug;92(2):162-7.

7. Prophylaxis Against Venous Thrombosis Indications for prophylaxis against venous thrombosis Hereditary hypercoaguable states Recurrent venous or pulmonary thromboemboembolism Cancer Risk of thromboembolism with discontinuation of warfarin: 15% per year Risk reduction with warfarin: 80% Hull RD et al. The diagnosis of acute, recurrent, deep-vein thrombosis: a diagnostic challenge. Circulation 1983 Apr;67(4):901-6. Lagerstedt CI et al. Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis. Lancet 1985 Sep 7;2(8454):515-8. Levine MN et al. Optimal duration of oral anticoagulant therapy: a randomized trial comparing four weeks with three months of warfarin in patients with proximal deep vein thrombosis. Thromb Haemost 1995 Aug;74(2):606-11.

8. Acute venous thromboembolism risk of recurrent venous thromboembolism Early without anticoagulation: 50% One month of warfarin: 8 to 10% Three months of warfarin: 4 to 5% Levine MN et al. Optimal duration of oral anticoagulant therapy: a randomized trial comparing four weeks with three months of warfarin in patients with proximal deep vein thrombosis. Thromb Haemost 1995 Aug;74(2):606-11. Research Committee of the British Thoracic Society. Optimum duration of anticoagulation for deep-vein thrombosis and pulmonary embolism. Lancet 1992 Oct 10;340(8824):873-6. Kearon C; Hirsh J Management of anticoagulation before and after elective surgery.N Engl J Med 1997 May 22;336(21):1506-11.

9. Arterial Thromboembolism Atrial Fibrillation Overall risk of systemic thromboembolism without anticoagulation: 4 to 5% per year Risk reduction: 66% risk of stroke and systemic thromboembolism can be further stratified Lip GY; Lowe GD. ABC of atrial fibrillation. Antithrombotic treatment for atrial fibrillation. BMJ 1996 Jan 6;312(7022):45-9. Albers GW et al. Antithrombotic therapy in atrial fibrillation. Chest 2001 Jan;119(1 Suppl):194S-206S.

10. Arterial Thromboembolism Atrial Fibrillation patients with a previous stroke or transient ischemic attack Recurrence risk: 12% per year Recurrence risk on aspirin: 10% per year Recurrence risk on warfarin: 4% per year Lip GY; Lowe GD. ABC of atrial fibrillation. Antithrombotic treatment for atrial fibrillation. BMJ 1996 Jan 6;312(7022):45-9. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Analysis of pooled data from five randomized controlled trials. Arch Intern Med 1994 Jul 11;154(13):1449-57.

11. Arterial Thromboembolism Atrial Fibrillation Patients with a history of heart failure, hypertension, or diabetes or who have a dilated left atrium or impaired ventricular function by echocardiography Risk of stroke or thromboembolism: 8% per year Risk on warfarin: 2% per year Lip GY; Lowe GD. ABC of atrial fibrillation. Antithrombotic treatment for atrial fibrillation. BMJ 1996 Jan 6;312(7022):45-9. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Analysis of pooled data from five randomized controlled trials. Arch Intern Med 1994 Jul 11;154(13):1449-57.

12. Arterial Thromboembolism Atrial Fibrillation Patients less than 65 years, no history of hypertension or diabetes or risk factors for stroke Risk of stroke or thromboembolism: 1 to 2% per year Risk on aspirin or warfarin: =1% per year Lip GY; Lowe GD. ABC of atrial fibrillation. Antithrombotic treatment for atrial fibrillation. BMJ 1996 Jan 6;312(7022):45-9. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Analysis of pooled data from five randomized controlled trials. Arch Intern Med 1994 Jul 11;154(13):1449-57.

13. Arterial Thromboembolism Left ventricular dysfunction 18% increase in stroke risk for every 5% reduction in left ventricular ejection fraction Risk reduction with aspirin: 56% Risk reduction with warfarin: 81% Loh E et al. Ventricular dysfunction and the risk of stroke after myocardial infarction. N Engl J Med 1997 Jan 23;336(4):251-7.

14. Prosthetic Heart Valves Prosthetic Heart Valves Risk of stroke and thromboembolism: 4% per patient year Risk on aspirin: 2.2% per patient year Risk on warfarin: 0.7 to 1.0% per patient year Mitral valve prosthesis care twice the risk of aortic valve prosthesis Cannegieter SC et al. Thromboembolic and bleeding complications in patients with mechanical heart valve prostheses. Circulation 1994 Feb;89(2):635-41.

15. Risk of Bleeding with Anticoagulation Age Comorbid conditions Type of surgery Prolonged, complex surgery vs. simple, minor procedures Anticoagulant regimen and intensity Length of warfarin therapy Use of other drugs affecting hemostasis Stability of anticoagulation Degree of monitoring Otley, CC, et al. Continuation of medically necessary aspirin and warfarin during cutaneous surgery. Mayo Clin Proc 2003; 78:1392. Nieuwenhuis HK et al. Identification of risk factors for bleeding during treatment of acute venous thromboembolism with heparin or low molecular weight heparin. Blood 1991 Nov 1;78(9):2337-43. Levine, MN, et al. Hemorrhagic complications of anticoagulant treatment. Chest 1995; 108:276S. Torn M. Rosendaal FR. Oral anticoagulation in surgical procedures: risks and recommendations. Br J Haematol 2003 Nov;123(4):676-82.

16. Risk of Bleeding with Anticoagulation Minimal risk of bleeding with two day course of intravenous heparin Marked increase in risk of major bleed to 3% immediately postoperatively General risk of bleeding with continuous heparin in patients with acute thromboembolism is �5% Incidence of major bleeding during first five days of therapy in patients with DVT at �high risk of bleeding� is 11% Levine, MN, et al. Hemorrhagic complications of anticoagulant treatment. Chest 1995; 108:276S. Hull RD, et al. Heparin for 5 days as compared with 10 days in the initial treatment of proximal venous thrombosis. N Engl J Med 1990 May 3;322(18):1260-4 .

17. Management of anticoagulation in patients undergoing elective surgery One prospective study evaluated 22 patients with a baseline INR of 2.6 INR fell to 1.6 at 2.7 days and 1.2 at 4.7 days. After cessation of warfarin, it usually takes a few days for the INR to fall below 2.0 White RH, et al. Temporary discontinuation of warfarin therapy: changes in the international normalized ratio. Ann Intern Med 1995 Jan 1;122(1):40-2.

18. Management of anticoagulation in patients undergoing elective surgery General Recommendations In patients with an INR between 2.0 and 3.0, warfarin should be held for three to four days to allow the INR to fall to a level between 1.5 and 2.0 If a more rapid reversal is required, consideration can be made to administering oral or intravenous vitamin K

19. Management of anticoagulation in patients undergoing elective surgery Venous Thromboembolism Within 1 month 1 percent absolute increase in risk of recurrence Heparin therapy recommended both before and after surgery 2 to 3 months Risk of recurrence significantly reduced 100 fold increase in post operartive thromboembolism Heparin therapy recommended postoperatively More than 3 months Bleeding associated with postoperative intravenous heparin offsets any beneficial effects of prevention Prophylactic measures, i.e. subcutaneous low molecular weight hepain and compression stocking, are associated with a lower risk of bleeding than intravenous heparin and are safer alternatives Kearon C. Hirsh J. Management of anticoagulation before and after elective surgery. N Engl J Med 1997 May 22;336(21):1506-11. Kakkar VV, et al. Low molecular weight versus standard heparin for prevention of venous thromboembolism after major abdominal surgery. Lancet 1993 Jan 30;341(8840):259-65.

20. Management of anticoagulation in patients undergoing elective surgery Arterial Thromboembolism: General considerations Risk for arterial thrombolism is similar both before and after surgery Risk of bleeding after surgery is relatively higher Elective surgery should be avoided in the first month after arterial thromboembolism. If surgery is essential recommendations are the same as for venous thromboembolism

21. Management of anticoagulation in patients undergoing elective surgery Arterial Thromboembolism Warfarin should be held for two days prior to procedure and reinstituted afterwards Low risk patients, e.g. nonvalvular atrial fibrillation Risk of thromboembolism does not warrant routine pre or postoperative therapy with intravenous heparin Prophylaxis doses of subcutaneous heparin or low-molecular weight heparin High risk patients with atrial fibrillation, e.g. left ventricular dysfunction Administer intravenous heparin until six hours before procedure and restarted as soon as possible after the surgery until warfarin is has been at therapeutic dose for 48 hours. Kearon C. Hirsh J. Management of anticoagulation before and after elective surgery. N Engl J Med 1997 May 22;336(21):1506-11.