Aspirin Safely Omitted from Antithrombotic Therapy in Patients with AF Undergoing PCI

Value-Based Care in Cardiometabolic Health Dec 2012, Vol 1, No 3
Mary Mosley

Munich, Germany—Dual antiplatelet therapy with an anticoagulant plus clopidogrel was safe and effective at 1 year in patients with atrial fibrillation (AF) or mechanical valves who underwent a percutaneous coronary intervention (PCI), with less bleeding compared with the current guideline-recommended approach of triple therapy that includes aspirin. The results from the What is the Optimal Antiplatelet and Anticoagulant Therapy in Patients with Oral Anticoagulation and Coronary Stenting (WOEST) trial were presented by Willem Dewilde, MD, TweeSteden Hospital in Tilburg, The Netherlands, at the 2012 European Society of Cardiology Congress.

“WOEST is the first study demonstrating that the omission of aspirin in patients treated with oral anticoagulants and having a coronary stent is safe,” said Dr Dewilde.

The WOEST study was undertaken because, as the name implies, the optimal strategy is unknown for this high-risk population who need anticoagulation because of the stroke risk related to their AF or mechanical valves, and antiplatelet therapy to prevent stent thrombosis. Approximately 30% of these patients have concomitant ischemic heart disease.

A total of 573 patients who received oral anticoagulants and were undergoing coronary stenting were prospectively randomized to double-therapy group (addition of clopidogrel 75 mg) or to triple-therapy group (addition of clopidogrel 75 mg and aspirin 80 mg). Drug therapy continued for 1 month after bare metal stenting and 1 year after drug-eluting stenting, and patients were followed for 1 year.

The study was conducted in 15 hospitals in The Netherlands and Belgium. The patients represented the average population with PCI, stated Dr Dewilde. Their mean age was approximately 70 years, most were men and slightly overweight, approximately 70% had hypertension, and approximately 70% had hypercholesterolemia. The indication for anticoagulation was AF in approximately 70% of patients, mechanical valve in 10%, and pulmonary embolism or other in the balance of patients. Of note, 25% had an acute coronary syndrome at baseline. Also, 5% had a history of gastrointestinal bleeding.

The WOEST study showed that adding clopidogrel to oral anticoagulation and omitting aspirin reduced bleeding and thrombotic and thromboembolic events.

At 1 year, the primary end point of all bleeding events (Thrombolysis In Myocardial Infarction minimum, minor, and major) was 19.5% with double therapy compared with 44.5% with triple therapy (hazard ratio [HR], 0.36; 95% confidence interval [CI], 0.26-0.50; P <.001). The curves diverged almost immediately, with less significant bleeding throughout the follow-up.

Dr Dewilde stated that there was a significant reduction in minimal and minor bleeding, and that major bleeding was numerically lower but did not reach statistical significance. No difference in intracranial bleeding was found, with 3 events in each group.

The secondary composite end points of stroke, death, myocardial infarction (MI), stent thrombosis, and target vessel revascularization (TVR) occurred in 11.3% of the dual-therapy group and 17.7% of the triple-therapy group (HR, 0.60; 95% CI, 0.38-0.94; P = .025).

All-cause mortality rates at 1 year were 2.6% with double therapy (a 61% reduction) compared with 6.4% with triple therapy (HR, 0.39; 95% CI, 0.16-0.93; P = .027).

The event rates for the other individual components of the secondary end point for the double-therapy and triple-therapy groups, respectively, were MI, 3.3% and 4.7%; TVR, 7.3% and 6.8%; stroke, 1.1% and 2.9%; and stent thrombosis, 1.5% and 3.2%.

“Although the number of the patients in the trial is limited,” said Dr Dewilde, “this is an important finding with implications for future treatment and guidelines in this group of patients known to be at high risk of bleeding and thrombotic complications.”

A few issues regarding the results were raised by Marco Valgimigli, MD, PhD, Chair of Cardiology, University Hospital of Ferrara, Italy, the discussant for the trial. The number of patients who were at low risk for stroke is not known, because the level of the stroke risk in the patients with AF was not reported.

Nearly 70% of the patients received a drug-eluting stent, and, of these, the patients in the triple-therapy group received treatment for 1 year, although there is evidence that double therapy for 6 months may reduce bleeding by 50% without a safety concern. Approximately 50% of the patients who received a bare metal stent received double therapy for 1 year. Dr Valgimigli said the international LEADERS study of 16,000 all-comers will provide information on the role of aspirin in the setting of adequate P2Y12 inhibition.

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