Single-arm study of bridging therapy with low-molecular-weight heparin for patients at risk of arterial embolism who require temporary interruption of warfarin.
BACKGROUND
When warfarin is interrupted for surgery, low-molecular-weight heparin is often used as bridging therapy. However, this practice has never been evaluated in a large prospective study. This study was designed to assess the efficacy and safety of bridging therapy with low-molecular-weight heparin initiated out of hospital.


RESULTS
This was a prospective, multicenter, single-arm cohort study of patients at high risk of arterial embolism (prosthetic valves and atrial fibrillation with a major risk factor). Warfarin was held for 5 days preoperatively. Low-molecular-weight heparin was given 3 days preoperatively and at least 4 days postoperatively. Patients were followed up for 3 months for thromboembolism and bleeding. Eleven Canadian tertiary care academic centers participated; 224 patients were enrolled. Eight patients (3.6%; 95% CI, 1.8 to 6.9) had an episode of thromboembolism, of which 2 (0.9%; 95% CI, 0.2 to 3.2) were judged to be due to cardioembolism. Of these 8 episodes of thromboembolism, 6 occurred in patients who had warfarin deferred or withdrawn because of bleeding. There were 15 episodes of major bleeding (6.7%; 95% CI, 4.1 to 10.8): 8 occurred intraoperatively or early postoperatively before low-molecular-weight heparin was restarted, 5 occurred in the first postoperative week after low-molecular-weight heparin was restarted, and 2 occurred well after low-molecular-weight heparin was stopped. There were no deaths.


CONCLUSIONS
Bridging therapy with subcutaneous low-molecular-weight heparin is feasible; however, the optimal approach for the management of patients who require temporary interruption of warfarin to have invasive procedures is uncertain.
Kovacs
M J
MJ
London Health Sciences Centre, 800 Commissioners Rd E, London, Ontario, Canada N6A 4G5. michael.kovacs@lhsc.on.ca
Kearon
C
C
Rodger
M
M
Anderson
D R
DR
Turpie
A G G
AG
Bates
S M
SM
Desjardins
L
L
Douketis
J
J
Kahn
S R
SR
Solymoss
S
S
Wells
P S
PS
D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D001157:Arterial Occlusive Diseases / Q000453:epidemiology / Q000517:prevention & control*; D001241:Aspirin / Q000008:administration & dosage; D001281:Atrial Fibrillation / Q000601:surgery*; D016063:Blood Loss, Surgical; D015331:Cohort Studies; D017985:Dalteparin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D017558:Elective Surgical Procedures; D005240:Feasibility Studies; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D019934:International Normalized Ratio; D007431:Intraoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D011183:Postoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D019106:Postoperative Hemorrhage / Q000139:chemically induced; D011292:Premedication; D011300:Preoperative Care; D011446:Prospective Studies; D012306:Risk; D013923:Thromboembolism / Q000453:epidemiology / Q000517:prevention & control*; D016896:Treatment Outcome; D014812:Vitamin K / Q000008:administration & dosage; D014859:Warfarin / Q000008:administration & dosage*
D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin; D001241:Aspirin; D017985:Dalteparin