MUNICH -- Atrial fibrillation patients on anticoagulation therapy don't require clopidogrel (Plavix) plus aspirin following stenting and it's aspirin, not clopidogrel, that should be omitted, researchers said.
In a small, randomized trial patients taking warfarin plus clopidogrel had significantly less bleeding than those randomized to clopidogrel, aspirin, and an anticoagulant - 19.5% versus 44.9% HR 0.36 (95% CI 0.26 to 0.50 P<0.001), reported Willem Dewilde, from TweeSteden Hospital in The Netherlands, and colleagues.
Moreover, skipping aspirin did not increase mortality, stent thrombosis, or MI, Dewilde said here at the European Society of Cardiology meeting.
"We originally didn't mean to show that the rate of death would be lower, but we wanted to ensure that the rate of all-cause death would not be higher," Dewilde said. "I think we can say that reducing the bleeding events means also reducing hospital costs and reducing mortality."
"Bleeding is such a huge issue in atrial fibrillation patients undergoing stenting," said David R. Holmes, MD, from the Mayo Clinic in Rochester, Minn.
Holmes, a past president of the American College of Cardiology, moderated the ESC Hot Line press conference where the results from Dewilde's WOEST trial were presented.
"Studies such as this randomized trial that are appropriately powered for the primary endpoint have the chance to change the guidelines. Will they change overnight? No," Holmes said. "Will these results change clinical practice overnight? Clearly, they may."
Noting that vitamin K antagonists (mostly warfarin) were the anticoagulants used in the study, Holmes said that it's premature to extrapolate the results to new oral anticoagulants such as dabigatran (Pradaxa) or rivaroxaban (Xarelto).
But study discussant Marco Valgimigli, MD, from the University of Ferrara in Italy trumpeted the take home from WOEST: "The taboo of discontinuing or omitting aspirin in the contemporary environment has finally been broken."
WOEST (What is the Optimal Antiplatelet and Anticoagulation Therapy in Patients with oral Anticoagulation and Coronary Stenting) is the first randomized trial to address the optimal antiplatelet therapy in patients on oral anticoagulants undergoing PCI.
Long-term oral anticoagulation is necessary in most patients with atrial fibrillation and patients with mechanical heart valves. In this trial, 70% of patients had Afib, while 10% had new valves.
Triple therapy is recommended by the guidelines for this patient population, but it also increases the risk of major bleeding.
"These investigators should be congratulated for taking the bold step of testing whether aspirin was even necessary in the contemporary era," Elliott Antman, MD, from Brigham and Women's Hospital in Boston told MedPage Today.
"The guidelines say that aspirin is a foundational element of antiplatelet therapy for patients with ischemic heart diseases, including those undergoing stenting. These results could lead to a fundamental shift in practice, but it's important to be cautious and examine all the details of the study first," Antman, a spokesperson for the American Heart Association said.
In WOEST, 537 patients already on oral anticoagulants were randomized 1:1 to dual therapy, which included 75 mg of clopidogrel, or triple therapy, which included the same dosage of clopidogrel plus 80 mg aspirin.
Patients receiving bare metal stents stayed on clopidogrel plus aspirin for 1 month minimum, while those with drug-eluting stents (DES) (N-65%) remained on it for 1 year.
Valgimigli questioned the need to keep DES patients in the triple therapy group on clopidogrel for a year.
"There is evidence that 6 months of dual antiplatelet therapy may cut bleeding by 50% without safety concerns," he said.
In addition, he wondered if patients in the triple therapy group who were at a low risk of stroke could have discontinued warfarin, further diminishing bleeding risk.
When researchers analyzed various subgroups such as age, gender, different indications for oral anticoagulation therapy, and stent type, they found no changes in bleeding risk.
When they examined aspirin compliance, they found that noncompliance correlated with an increase in bleeding events.
Interestingly, although overall bleeding events in the triple therapy group were twice that seen in the dual therapy arm, the rate of intracranial bleeding was the same between the two groups.
Several comments were made regarding the difference in GI bleeds, which seemed to be the primary driver of the high bleeding rate in the triple therapy group, Antman said.
Patients in the trial were mostly men and slightly overweight. About 35% of patients were on proton pump inhibitors at baseline.
The secondary endpoint, a combination of all-cause death, myocardial infarction, stroke, target vessel revascularization, and stent thrombosis was significantly lower at 1 year in the double therapy group (11.3% versus 17.7%).
Individually, all components of the secondary endpoint were lower in the double therapy group, but the only one to reach significance was all-cause mortality (2.4% versus 6.4%).
"We propose a strategy of oral anticoagulation therapy plus clopidogrel without aspirin could be used in these patients while undergoing PCI," Dewilde concluded.
Primary source: European Society of Cardiology
Source reference: Dewilde W, et al "The WOEST Trial: First randomized trial comparing two regimens with and without aspirin in patients on oral anticoagulants therapy undergoing coronary stenting" ESC 2012; Abstract.