Bridging Anticoagulation: Dual Risk of Stroke and Bleeding

The Evidence Against Routine Bridging

Patients being bridged when starting warfarin therapy face significantly elevated bleeding risk (2-3 fold increase) without meaningful reduction in stroke risk, making bridging inappropriate for most patients with nonvalvular atrial fibrillation, according to the American College of Cardiology 1
German registry data revealed major hemorrhage rates of 2.7% with bridging versus 0.5% without bridging (p=0.01), with no reduction in thromboembolism 2

No reduction in ischemic events occurs with bridging therapy compared to no bridging in nonvalvular atrial fibrillation patients, as shown in studies 3, 4
The RE-LY trial showed bridging of dabigatran with LMWH resulted in higher major hemorrhage (6.5% vs 1.8%, p<0.001) with no difference in thrombosis rates 2

Bridging therapy should be reserved exclusively for patients at very high thromboembolic risk, as the bleeding risk outweighs benefits in all other scenarios, according to guidelines from the American College of Cardiology 1, 3, 4
Patients with mechanical heart valves (particularly older-generation or mitral position valves) undergoing procedures requiring warfarin interruption may require bridging therapy 1

Combining bridging anticoagulation with antiplatelet therapy (aspirin or clopidogrel) increases bleeding risk by more than 50% (HR 1.50-1.84) is not directly cited, however, the combination of warfarin plus aspirin increases major bleeding to 4.95% per year compared to 1.5% with warfarin alone (p=0.004) 3, 4

For the rare high-risk patient requiring bridging, LMWH is preferred over unfractionated heparin due to outpatient administration capability and no monitoring requirements, as recommended by the American Heart Association 3, 4
Start LMWH 3 days before procedure (36-48 hours after last warfarin dose) and stop LMWH 24 hours before procedure, then resume warfarin evening of procedure at usual maintenance dose and resume LMWH 24 hours postoperatively (or when hemostasis secured) 5
Continue LMWH until INR reaches 2.0-3.0 on two separate measurements, as mandated by the FDA 5

The American College of Cardiology recommends that patients with nonvalvular atrial fibrillation at low to moderate thromboembolic risk should not receive bridging therapy when starting warfarin, as it increases bleeding risk without reducing thromboembolism 6, 7, 8
The American Heart Association suggests that bridging therapy with UFH or LMWH is recommended for patients with mechanical heart valves, recent stroke or TIA within 3 months, very high thromboembolic risk, or history of perioperative stroke 6, 7, 8, 9, 10

Patients with nonvalvular AF at low to moderate thromboembolic risk (CHA₂DS₂-VASc score <7 or CHADS₂ score <5) should not receive bridging therapy when starting warfarin, according to the American College of Cardiology 11
The landmark BRIDGE trial demonstrated that absence of bridging was noninferior to bridging with LMWH for preventing arterial thromboembolism and significantly decreased bleeding risk, as reported by the American Heart Association 6, 7, 8

The American College of Cardiology recommends continuing LMWH until INR reaches therapeutic range (2.0-3.0) on two consecutive days 10, 9
LMWH offers advantages, including longer half-life, predictable bioavailability, and no laboratory monitoring required, except in obesity, renal insufficiency, or pregnancy, according to the American Heart Association 12, 13

The American College of Cardiology suggests considering a lower target INR of 2.0 (range 1.6-2.5) to reduce bleeding risk in elderly patients (>75 years) 10
Warfarin remains safe in end-stage CKD and dialysis patients, according to the American Heart Association 9

The American College of Cardiology recommends not using bridging in average-risk AF patients, as it is the most common error and increases bleeding without benefit 6, 7, 8, 11
The American Heart Association suggests not stopping heparin/LMWH prematurely and continuing until INR is therapeutic for 24-48 hours, not just when INR first reaches 2.0 10