BOSTON—As more anticoagulants bust onto the market, the optimal strategy for managing atrial fibrillation (AF) patients on this class of drugs after a surgical procedure is controversial, Michael R. Gold, MD, PhD, said during a presentation at the 2012 Boston Atrial Fibrillation Symposium (BAFS). He added that figuring out the best way to manage cardioversion and device implantation patients may be even more difficult.

“Patients with atrial fibrillation frequently need surgery or procedures which may or may not be related to whether they have arrhythmias,” said Gold, director of the division of cardiology at the Medical University of South Carolina in Charleston (MUSC). “The optimal strategy for managing antithrombotic agents perioperatively is often controversial and the newer anticoagulants only add further complexity to this decision process.”

Gold pointed out that guidelines have not been updated since 2003 and include only the agent warfarin. "We have very little [information] to guide us,” he said.

The 2003 guidelines put forth the following recommendations:

• Hold warfarin for low-risk patients and proceed with or without heparin products;
• Hold warfarin and proceed with at least prophylaxis pre- and post-procedure for moderate risk patients; and
• Bridge high-risk patients with heparin products at therapeutic dosages.

Recently, published data have outlined that, for low-risk device patients, “a vast majority of clinicians simply hold anticoagulation,” Gold said.

As for high-risk patients with devices, “there seems to be an even split between bridging and holding anticoagulants,” he offered. For the patient population with mechanical valves, Gold said that most are bridging with anticoagulants, a strategy that more recent data said may not be the best approach.

So, which strategy is best?

It has been previously reported that for patients on oral anticoagulation and undergoing a pacemaker procedure, it may be safe to continue warfarin. However, Gold said these data also showed an increased risk in patients administered low molecular weight heparin as a bridging strategy during these types of procedures.

More recently, a large 201-patient study assessed the affects of continuing warfarin compared to a bridging strategy in device patients, cited Gold. Gold said that study authors reported more hematomas in patients receiving devices when a bridging strategy was used compared to those administered warfarin or those in whom anticoagulation was held.

“What was concerning was that holding anticoagulation was associated with an increased risk in embolic events, particularly transient ischemic attacks (TIAs) or strokes,” Gold said. “The risk of holding warfarin was clearly there.”

Another randomized trial from the University of Michigan in Ann Arbor compared heparin initiation six hours or 24 hours post-device implantation. Researchers concluded that continuing warfarin was a better strategy than any that involved bridging heparin. Gold also referenced another study that evaluated patients undergoing cardiac resynchronization therapy which found an increased risk of bleeding in patients who underwent a bridging strategy compared with those continuing on warfarin.

However, other studies have challenged these findings, concluding that bridging strategies were safe and had no excess complications compared with warfarin continuation.

To better understand these data, Gold et al performed a meta-analysis of 13 studies that addressed the best strategy for the periprocedural management of device patients. They looked at both anticoagulation and antiplatelet therapy, as many patients present on dual antiplatelet therapy (DAPT) with clopidogrel or other agents.

Gold et al reported a bleeding complication rate close to 2 percent in patients administered no therapy. Results were similar for patients who had anticoagulation therapy withheld. “However, when you assess a dual antiplatelet therapy or heparin bridging strategy,” Gold said, “you see a marked increased in bleeding complications.”

Currently, there is very little data surrounding the administration of dabigatran (Pradaxa, Boehringer Ingelheim) to device patients. Therefore, Gold outlined the MUSC experience. In a 19-patient prospective study—16 new device implants and three pulse generator replacements—Gold et al found that nine patients did not have an interruption of dabigatran during device procedure. The researchers reported one minor complication—a hematoma, which did not require intervention.

The open label RE-LY registry, which assesses data from more than 600 device implants, showed nonsignificant trends toward lower major complication rates in patients on dabigatran when compared with warfarin. Patients on dabigatran also saw fewer major complications compared with patients bridged on warfarin.

RE-LY registry data also showed that the embolic complication rate was low whether cardioversion patients were on therapeutic warfarin or dabigatran—less than 1 percent in all groups (dabigatran 150 mg, 110 mg or warfarin). Those on the 150 mg dose of dabigatran had the lowest complication rate.

Gold concluded the following:

• Patients who had anticoagulation stopped between a 24- to 48-hour period prior to procedure saw significantly more bleeding problems with warfarin compared with dabigatran;

• Based on the perioperative conclusions from the RE-LY trial, dabigatran was associated with similar risks of perioperative bleeds and thrombotic complications when compared with warfarin, even in patients having major or urgent surgery; and
• Patients receiving dabigatran were four times more likely to have surgical procedures performed within 48 hours of withholding anticoagulants and did so with a lower risk of bleeding compared to those on warfarin.

Heparin bridging or DAPT was associated with increased bleeding. Therefore, continuing patients on anticoagulants is often a safer approach, Gold said. Additionally, he concluded that cardioversion patients on dabigatran have a lower risk of stroke or embolic complications.

“Dabigatran and warfarin have similar overall bleeding complication rates perioperatively for major or minor surgeries,” Gold summed. “However, dabigatran is safer than warfarin with heparin bridging or if anticoagulation is being withheld for less than 48 hours.”