EWOLUTION Analysis Backs LAA Closure in High-Risk Patients Taking DAPT, Not Warfarin, After Procedure

PARIS, France—In a registry of patients with nonvalvular atrial fibrillation implanted with the Watchman left atrial appendage (LAA) closure device, 1-year results suggest the intervention can reduce the risk of stroke without unduly increasing the risk of serious adverse events for those treated with dual antiplatelet therapy (DAPT) alone.

New findings from the multicenter, single-arm EWOLUTION registry show the 1-year risk of ischemic stroke was 1.4% among individuals who received the Watchman device (Boston Scientific) and DAPT rather than the standard 45-day course of oral anticoagulation.

In treating these high-risk, mostly warfarin-ineligible patients with LAA closure, investigators say the risk of ischemic stroke appears to be significantly lowered when compared with the predicted risk among oral anticoagulation-ineligible patients with an equivalent risk of stroke based on the CHA2DS2-VASc score.

Martin Bergmann, MD (Cardiologicum Hamburg, Germany), who presented safety and efficacy data of the DAPT subgroup treated in the EWOLUTION registry, said that while LAA closure for stroke prevention has been incorporated into clinical guidelines, studies thus far have been conducted in those eligible for oral coagulation. Those guidelines also note that platelet inhibition alone is ineffective for stroke prevention.

“In Europe, we have the feeling that the device is currently positioned best for patients that have a contraindication—relative or absolute—for oral anticoagulation, including the [non-vitamin K antagonist oral anticoagulants (NOACs)],” he told TCTMD. “This is where we’re using it and this is also where we get reimbursement. Yet this patient cohort doesn’t have any data.”

Cohort of Watchman Patients Treated With DAPT Only

At the recently held Heart Rhythm 2017 meeting, Lucas Boersma, MD (St. Antonius Hospital Nieuwegein, the Netherlands), presented 1-year safety and efficacy data from 1,020 patients treated with Watchman in the EWOLUTION registry, of whom 73% had a contraindication to long-term oral anticoagulation. In the main study, 60% of patients were taking DAPT.

In the DAPT substudy, which was presented last week at EuroPCR 2017 in Paris, France, investigators reported data on 605 oral anticoagulation-ineligible patients who received the Watchman device and were treated with DAPT following the procedure. To TCTMD, Bergmann noted this was a high-risk cohort, with approximately one-third of patients being older than 80 years. Nearly 90% of treated patients had a CHA2DS2-VASc score ≥ 3. The majority of patients discontinued DAPT in the first 6 months.

Major bleeding and major bleeding excluding procedural-related bleeds (those occurring in the first 7 days) occurred in 2.5% and 2.1% of patients, respectively. Fatal bleeding occurred in four patients (0.5%). To TCTMD, Bergmann said that based on their HAS-BLED score, the rate of major bleeding among a similar group of patients receiving oral anticoagulation would be expected to be 5.1%.

In terms of efficacy, there were 11 strokes (1.4%), with no fatal or hemorrhagic events and one disabling event. Compared with the predicted risk in patients with a similar CHA2DS2-VASc score unable to take oral anticoagulation, the risk of ischemic stroke was lower by 81% (down from an expected rate of 7.5%). Similarly, the risk of ischemic stroke, TIA, and systemic embolism—1.8% at 1 year in EWOLUTION—was also significantly reduced compared with the predicted risk in warfarin-ineligible patients with a similar CHA2DS2-VASc score.  

“It suggests efficacy. I’m not saying proving, but it suggests a benefit,” said Bergmann, referring to use of Watchman in DAPT-treated patients not taking oral anticoagulation. “What’s interesting is that all of the [ischemic] events occurred in highest-risk patients.”

The researchers said the stroke rate per 100 patient-years among the highest-risk Watchman-treated patients (CHA2DS2-VASc score ≥ 3) in the EWOLUTION-DAPT subgroup compares favorably to the stroke rate observed with apixaban-treated patients in the ARISTOTLE study—1.61% with LAA closure and DAPT versus 1.48% with apixaban (Eliquis; Bristol-Myers Squibb).        

Given that the efficacy for stroke prevention with Watchman in this mostly anticoagulation-ineligible cohort is similar to the efficacy observed with NOACs, the researchers suggest the European Society of Cardiology guidelines recommending LAA closure for patients with A-fib who are ineligible for anticoagulation, which is currently a class IIb, level of evidence B recommendation, should be strengthened.  

“Don’t worry about the patient being oral anticoagulation-ineligible,” Bergmann told TCTMD. “DAPT directly after the implantation is safe, and you don’t run the risk of increased stroke.”