Anticoagulant Bridging During Procedures Increases Bleeding Risk

By Will Boggs MD

NEW YORK (Reuters Health) - Bridging anticoagulation during interruption of oral anticoagulants for procedures in patients with atrial fibrillation (AF) is associated with increased risk of bleeding and adverse events, according to findings from the ORBIT-AF registry.

Study author Dr. Benjamin A. Steinberg from Duke University Medical Center, Durham, North Carolina was not entirely surprised. He told Reuters Health by email, "Prior data from the acute coronary syndrome (ACS) population have suggested that switching among antithrombotics can be a set-up for hazard, and this was also seen in EP (electrophysiology) device trials - in certain situations, continuing chronic anticoagulation seems to be the most prudent course. Of course, identifying those patients and situations is paramount."

Many patients with AF undergo procedures that may require temporary interruption of oral anticoagulation, and some researchers have advocated use of short-acting anticoagulants during these interruptions to bridge the patient in hopes of reducing the risk of embolic events during the interruption.

Dr. Steinberg and colleagues used data from 7372 patients in the ORBIT-AF registry to assess how often this happens and how outcomes compare between patients who were or weren't bridged.

Bridging anticoagulation was used for 24% of the 2803 reported interruptions, the researchers found.

As reported December 12th online in Circulation, anticoagulants used during these interruptions included low-molecular-weight heparin (73%), unfractionated heparin (15%), fondaparinux (1.1%), or some other anticoagulant (11%).

For patients chronically treated with warfarin, time to achievement of therapeutic INRs was significantly shorter with bridging than without (median, 17 vs 23 days; p<0.001).

Although event rates during interruption were low, they were significantly higher with bridging anticoagulation for adverse events in general (5.3% vs 2.8%), major bleeding (3.6% vs 1.2%), hospitalization (2.2% vs 0.7%), and cardiovascular hospitalization (4.2% vs 2.2%).

In multivariate-adjusted analysis, the use of bridging anticoagulation during interruption was associated with a 3.84-fold increased risk of major bleeding or bleeding hospitalization and a 94% increased risk of the composite of myocardial infarction, bleeding, stroke or systemic embolism, hospitalization, or death within 30 days.

The association between bridging and adverse outcomes persisted after adjustment for baseline concomitant antiplatelet use.

"These data do not support the use of routine bridging in anticoagulated patients with AF, and additional data are needed to identify best practices around anticoagulation interruptions," the researchers conclude.

"I think the message is that interrupting anticoagulation in patients with AF can be a period of risk, for both bleeding and thromboembolism, and decisions around whether to interrupt and whether to bridge should not be taken lightly," Dr. Steinberg said. "Certainly, additional trial data will continue to help us clarify these issues."

In the meantime, he said, "I think these data support the guidelines - bridging in patients where anticoagulation really needs to be interrupted (based on the procedure type; e.g., neurological surgery), in the patient at high risk of thromboembolic events (e.g., prior history of an event, mechanical heart valve, etc.)."

In a related commentary, Dr. Amir Y. Shaikh and Dr. David D. McManus from the University of Massachusetts Medical School in Worcester write, "These findings fly somewhat in the face of conventional dogma and may begin a paradigm shift away from the routine use of a bridging strategy for AF patients undergoing procedures."

"Fortunately," they note, "two large randomized, placebo-controlled trials (BRIDGE and PERIOP-2) are underway to better inform peri-procedural anticoagulation decision-making."

"For the time being, however, this investigation calls into serious question whether or not, in our efforts to reduce peri-procedural thromboembolic complications from AF, we are in fact exposing patients to increased risk of harm from bleeding," they write.

Still unanswered, they add, is the question of whether uninterrupted oral anticoagulation is superior to interrupted oral anticoagulation without bridging.

SOURCE: https://bit.ly/1rM1uyW

Circulation 2014.

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