CHICAGO, June 5 -- A revision of guidelines on use of blood thinners in endoscopy patients is likely to recommend against stopping low-dose aspirin therapy, according to a preview offered here at Digestive Disease Week.
Scheduled for final updating in the next few months, the revised guidelines from the American Society for Gastrointestinal Endoscopy (ASGE) will probably continue to recommend that more potent antiplatelet and anticoagulant drugs be stopped prior to "high-risk" endoscopic procedures, according to Michelle Anderson, M.D., of the University of Michigan.
Dr. Anderson, a member of the committee leading the guideline revision, gave a presentation here on the draft that will be submitted to the ASGE's governing board for approval this summer.
She emphasized that changes were likely before the final version is published in about six months.
ASGE first published guidelines for handling aspirin, warfarin, and heparin in endoscopy in 2002.
A 2005 update covered newer antiplatelet and anticoagulant drugs such as clopidogrel (Plavix) and low molecular weight heparin products such as enoxaparin (Lovenox).
Dr. Anderson said another update is desirable because of recent research -- including findings that low-dose aspirin does not substantially increase bleeding events in endoscopy, while stopping it even for short periods does increase the risk of thrombosis.
Consequently, "don't stop aspirin" is likely to be a major recommendation in the new guidelines, Dr. Anderson said.
"The reason we think that will be in the final guideline is because we think the risk associated with stopping the aspirin is far greater to the patient," she said.
The 2002 guideline was more equivocal: it said aspirin could be continued in patients "in the absence of a pre-existing bleeding disorder."
Recommendations involving other types of antithrombotic medications will be more detailed than in existing guidelines, but probably will not contain major changes, Dr. Anderson said.
She said the primary framework would examine three types of factors that collectively influence the risk of adverse effects: those associated with the patients themselves, with the medications they're taking, and with the procedure.
"As gastroenterologists, we tend to focus on procedural factors because we want, rightly, to lower risk of bleeding complications," she said. "But really it's a very complex set of things that cause adverse events."
Some patient factors carry high risk while others don't, she said.
For example, mechanical valves in the mitral valve or a recent coronary stent placement put the patient at high risk for thrombotic events, she said, whereas mechanical valves in the aortic position and atrial fibrillation without valvular heart disease are comparatively low-risk.
Depending on the degree of risk, patients on chronic warfarin scheduled for endoscopy may have the drug simply withheld a few days beforehand, or switched to unfractionated heparin until warfarin may be safely restarted, according to the draft guideline.
Management of antiplatelet and anticoagulant therapy also depends on whether endoscopic procedures are elective or urgent, Dr. Anderson said.
For elective procedures, if continuing on the medications poses a risk of excessive bleeding, the agents should generally be stopped, according to the draft.
Patients at very high risk for thrombotic events -- such as pregnant women with mechanical heart valves or patients with recent coronary stent placements -- should simply defer elective endoscopy.
In an urgent setting, countermeasures such as platelet transfusion may be used in patients receiving antiplatelet agents. For patients on warfarin or heparin products, antidotes may be called for.
Dr. Anderson said patients who are actively bleeding and requiring endoscopy should generally have antiplatelet and anticoagulant medications stopped until hemostasis is achieved. But the drugs can be restarted immediately thereafter, she said.
But she also emphasized that patients need individualized treatment.
For nonbleeding patients, Dr. Anderson described an algorithm that starts by separating patients according to whether they are on antithrombotics temporarily or for the long term.
Management of those on chronic or indefinite therapy then depends on the procedure-associated risks. No change in antithrombotic medications is necessary for low-risk procedures such as diagnostic endoscopy.
For elective high-risk procedures, such as polypectomy or ultrasound-guided fine needle aspiration, management should take into account the specific medication and the risks associated with the underlying condition.
Dr. Anderson said that endoscopists would be encouraged to consult with the patients' other physicians who had prescribed the antithrombotic therapy, especially in tricky cases.
"Know what your staff and your colleagues are doing," she said as part of her summary of the draft.
As is becoming customary in treatment guidelines, the ASGE's update will grade the quality of evidence behind the recommendations.
In addition, relatively weak recommendations will be signaled with phrases such as "we suggest," while terms such as "we recommend" will distinguish those with stronger support, Dr. Anderson said.
She added that the organization was taking pains to harmonize its guidelines with those of other organizations.
The American College of Cardiology and the American Heart Association, in particular, currently have a joint statement on handling of antithrombotic therapy in patients undergoing other medical procedures.
The final guidelines will be published in the ASGE's journal, Gastrointestinal Endoscopy, and also on .