The ALSTER-FLX Registry: 3-Month outcomes after left atrial appendage occlusion using a next-generation device, a matched-pair analysis to EWOLUTION

Background: The new-generation WATCHMAN FLX (Boston Scientific) device for left atrial appendage occlusion has been modified in various aspects to improve procedural results. No comparison of the WATCHMAN FLX device with the previous WATCHMAN device is available. Objective: We aimed to compare procedural results with WATCHMAN FLX in patients on dual antiplatelet therapy at ∼3 months with data with WATCHMAN (EWOLUTION [Registry on WATCHMAN Outcomes in Real-Life Utilization]). Methods: One hundred sixty-four consecutive patients receiving the WATCHMAN FLX device in 4 European centers were included in the retrospective ALSTER-FLX registry. As a control group for a matched-pair analysis, 1020 patients treated with the WATCHMAN device and data up to first follow-up (∼3 months) from EWOLUTION were used. Results: Implantation was successful in all ALSTER-FLX patients (100%) and similar to results in EWOLUTION (99%) (P = .2). We observed no stroke or device embolization in ALSTER-FLX similar to EWOLUTION (stroke 0.5%, device embolization 0.4%) at 3 months. Numerically less ALSTER-FLX patients (2.4%) developed a device-associated thrombus as compared with 3.7% EWOLUTION patients, yet without reaching statistical significance after matching (median [95% confidence interval] device-associated thrombus pairwise event difference 2 [0–6]; P = .1). WATCHMAN FLX implantation was associated with a significant higher sealing rate compared with EWOLUTION at 3 months (ALSTER-FLX 90% vs EWOLUTION 79.4%; P = .039 after matching). Major nonprocedural bleeding events and mortality were similar after matching (median event difference for bleeding 0 [−3 to 3]; P = .6 and death 1 [−2 to 4]; P = .3). Conclusion: Periprocedural, early 3-month outcomes with WATCHMAN FLX demonstrate a similar safety profile and an improved sealing rate compared to the WATCHMAN device.