Bridging Anticoagulation: Primum Non Nocere
Bridging Anticoagulation: Primum Non Nocere
Periprocedural warfarin interruption remains a routine practice for many clinicians. Recent data suggest that 40% to 60% of OAC interruptions may be unnecessary. A 2005 survey of dermatologic surgeons revealed that 44% of them routinely interrupt OAC for dermatologic surgery—a procedure with low bleeding risk. Other surveys similarly reveal that 90% to 100% of physicians would interrupt OAC and even bridge patients who are undergoing low bleeding-risk procedures regardless of TE risk.
OAC should not be interrupted for patients undergoing low bleeding-risk procedures, particularly those at high risk for TE. Uninterrupted warfarin throughout the periprocedural period is not associated with elevated bleeding risk for many procedures and surgeries, especially when a lower international normalized ratio (INR) goal of 2.0 is targeted (Table 2). Ironically, continuous warfarin therapy can paradoxically reduce periprocedural bleeding relative to interrupted warfarin with heparin bridging.
Moreover, warfarin interruption and reinitiation can be associated with an increased incidence of stroke. In 1 retrospective study, warfarin initiation more than doubled the stroke risk during the first week compared with nonanticoagulated, matched control subjects. This paradox may be due to early depletion of the vitamin K–dependent factors, proteins C and S, creating a hypercoagulable milieu.
Relatively major operations may also tolerate continuation of OAC. For example, certain orthopedic surgeries may also prove tolerant to uninterrupted OAC therapy. Rhodes et al. retrospectively analyzed 77 patients undergoing total knee arthroplasty; 38 patients remained on warfarin throughout the perioperative period. They found no significant difference in the rates of blood transfusion, wound complications, or reoperation between the 2 groups.
Randomized studies appear to confirm these observations. Two randomized prospective trials have been conducted to directly compare the safety and efficacy of uninterrupted warfarin versus bridging with heparin. In a 2007 study, 214 patients on OAC undergoing dental extraction were randomized to either continue warfarin or to stop warfarin and bridge with heparin. Interrupted warfarin without bridging was not studied. There were no TE events in either group, consistent with the low rate of TE seen in other studies. Importantly, nearly one-half of the patients were at presumably high TE risk, with either prosthetic valves or atrial fibrillation with valvular disease. The rate of bleeding was also similar between patients with uninterrupted warfarin versus those with heparin bridging (7.34% vs. 4.76%, respectively; p > 0.05).
BRUISE CONTROL (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial), published in 2013, randomized 681 high-risk patients undergoing pacemaker or defibrillator implantation to either uninterrupted OAC or interrupted OAC with heparin bridging. Due to the high TE risk of the study population, there was again no arm of interrupted OAC without bridging. The investigators found that heparin produced more than 4× as many clinically significant pocket hematomas than in those on uninterrupted warfarin (16% vs. 3.5%; p < 0.001). Strokes and transient ischemic attacks occurred in 2 patients on uninterrupted warfarin (0.3%), with no statistically significant difference between the groups.
Nevertheless, in many circumstances, interruption of chronic anticoagulation will be necessary to avoid excessive procedural- or surgical-related bleeding. To justify bridging anticoagulation, the risk of TE while off of anticoagulation should be great enough to justify the bleeding risk of bridging. However, as outlined in the following text, the TE risk is generally modest and outweighed by the risk of bridging-associated bleeding.
Avoid OAC Interruptions
Periprocedural warfarin interruption remains a routine practice for many clinicians. Recent data suggest that 40% to 60% of OAC interruptions may be unnecessary. A 2005 survey of dermatologic surgeons revealed that 44% of them routinely interrupt OAC for dermatologic surgery—a procedure with low bleeding risk. Other surveys similarly reveal that 90% to 100% of physicians would interrupt OAC and even bridge patients who are undergoing low bleeding-risk procedures regardless of TE risk.
OAC should not be interrupted for patients undergoing low bleeding-risk procedures, particularly those at high risk for TE. Uninterrupted warfarin throughout the periprocedural period is not associated with elevated bleeding risk for many procedures and surgeries, especially when a lower international normalized ratio (INR) goal of 2.0 is targeted (Table 2). Ironically, continuous warfarin therapy can paradoxically reduce periprocedural bleeding relative to interrupted warfarin with heparin bridging.
Moreover, warfarin interruption and reinitiation can be associated with an increased incidence of stroke. In 1 retrospective study, warfarin initiation more than doubled the stroke risk during the first week compared with nonanticoagulated, matched control subjects. This paradox may be due to early depletion of the vitamin K–dependent factors, proteins C and S, creating a hypercoagulable milieu.
Relatively major operations may also tolerate continuation of OAC. For example, certain orthopedic surgeries may also prove tolerant to uninterrupted OAC therapy. Rhodes et al. retrospectively analyzed 77 patients undergoing total knee arthroplasty; 38 patients remained on warfarin throughout the perioperative period. They found no significant difference in the rates of blood transfusion, wound complications, or reoperation between the 2 groups.
Randomized studies appear to confirm these observations. Two randomized prospective trials have been conducted to directly compare the safety and efficacy of uninterrupted warfarin versus bridging with heparin. In a 2007 study, 214 patients on OAC undergoing dental extraction were randomized to either continue warfarin or to stop warfarin and bridge with heparin. Interrupted warfarin without bridging was not studied. There were no TE events in either group, consistent with the low rate of TE seen in other studies. Importantly, nearly one-half of the patients were at presumably high TE risk, with either prosthetic valves or atrial fibrillation with valvular disease. The rate of bleeding was also similar between patients with uninterrupted warfarin versus those with heparin bridging (7.34% vs. 4.76%, respectively; p > 0.05).
BRUISE CONTROL (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial), published in 2013, randomized 681 high-risk patients undergoing pacemaker or defibrillator implantation to either uninterrupted OAC or interrupted OAC with heparin bridging. Due to the high TE risk of the study population, there was again no arm of interrupted OAC without bridging. The investigators found that heparin produced more than 4× as many clinically significant pocket hematomas than in those on uninterrupted warfarin (16% vs. 3.5%; p < 0.001). Strokes and transient ischemic attacks occurred in 2 patients on uninterrupted warfarin (0.3%), with no statistically significant difference between the groups.
Nevertheless, in many circumstances, interruption of chronic anticoagulation will be necessary to avoid excessive procedural- or surgical-related bleeding. To justify bridging anticoagulation, the risk of TE while off of anticoagulation should be great enough to justify the bleeding risk of bridging. However, as outlined in the following text, the TE risk is generally modest and outweighed by the risk of bridging-associated bleeding.
