201Left atrial appendage closure for stroke prevention in patients with atrial fibrillation: the difficult task of estimating the possible benefit in real life setting

Abstract

Transcatheter left atrial appendage (LAA) closure is an alternative strategy for stroke prevention in atrial fibrillation (AF) patients with an inacceptable risk of bleeding with oral anticoagulation (OAC). Recent observational analyses compared the ischemic stroke rate in AF patients after LAA closure with the rate expected for a same risk score population (if untreated). However, most patients receive various antithrombotic strategies after LAA closure, which should also be taken into account in this type of estimation. Methods: In patients treated with Watchman or Amplatzer LAA closure devices from 8 French centers, yearly rate of ischemic stroke during follow-up was calculated and compared to that expected for a same risk score population (if untreated). Adjustment was then made for exposure to antiplatelet therapy (APT) treatment, assuming that aspirin provides a 22% reduction in TE risk, and to oral anticoagulation (OAC) assuming that OAC provides a 64% reduction in TE risk. Theoretical yearly rate of bleeding was extrapolated from that reported with the HASBLED score. Results: A total of 469 consecutive AF patients (299 males, 74.968.9 years old, mean CHA2DS2-VASc score 4.561.4, HASBLED score 3.761.0) received LAA closure from March 2012 to January 2017. There were 272 Watchman devices (58%) and 197 Amplatzer devices (42%) implanted. At discharge, 36% received a single anti platelet APT, 23% received dual APT, 29% received oral OAC and no APT, 5% received OAC plus APT and 8% received no antithrombotic therapy. Mean follow up was 13613 months during which 70 major cardiovascular events (19 ischemic strokes, 18 major hemorrhages and 33 deaths) were recorded in 69 patients. The annual rate of ischemic stroke was 3.96%, which translates into a 43% relative risk reduction (95%CI 1 to 67%) as compared with the calculated stroke rate of 6.95% without the use of antithrombotic therapy for similar CHA2DS2-VASc score. After adjustment for exposure to APT and OAC, relative risk reduction was 13% (95%CI-59 to 52%). The annual rate of major bleeding in the study was 3.75%, which corresponds to a 48% relative risk reduction (95%CI 9 to 70%) as compared with the rate that would have been expected based on a comparable HAS-BLED score. As a result, clinical benefit was a relative risk reduction in combined ischemic stroke and bleeding events ranging from 45% (95%CI 20 to 63%) to 34% (95%CI 3 to 56%) after adjustment on antithrombotic use. Conclusions: AF patients treated with LAA closure and an antithrombotic strategy proposed on an individual basis had a significant reduction in the risk of events (stroke and/or bleeding) compared to their theoretical risk. This estimated benefit was not as dramatic as that seen in other registries and was variable according to the method of adjustment. A better identification of this benefit is needed, which might only be obtained in a specific randomized trial performed in patients with OAC contraindication.