A systematic review and meta-analysis comparing the clinical outcomes of the Watchman FLX versus Watchman 2.5 device for transcatheter left atrial appendage occlusion in patients with atrial fibrillation.

BACKGROUND: Transcatheter left atrial appendage occlusion (LAAO) prevents cardioembolic stroke in patients with non-valvular atrial fibrillation who cannot tolerate long term anticoagulation. Whether the second-generation Watchman FLX confers superior clinical outcomes over the first-generation Watchman 2.5 remains incompletely characterized. METHODS: We performed a PRISMA 2020-compliant systematic review and meta-analysis of studies comparing Watchman FLX with Watchman 2.5. Three electronic databases were searched through April 2026. Pooled risk ratios (RRs) and mean differences (MDs) with 95% confidence intervals (CIs) were derived using DerSimonian-Laird random-effects models. Nine prespecified outcomes were analyzed: procedural success, device-related embolism, device-related thrombosis (DRT), major bleeding, pericardial effusion, all-cause mortality, any stroke, ischemic stroke, and length of hospital stay (LOHS). RESULTS: Seven observational cohort studies enrolling 131,728 patients (Watchman FLX: n = 54,023; Watchman 2.5: n = 77,705) were included. All studies received Newcastle-Ottawa Scale scores of 8-9 (high quality). The Watchman FLX demonstrated significantly higher procedural success (RR 1.02 [1.02-1.02]; p < 0.00001) and significant reductions in pericardial effusion (RR 0.33 [0.27-0.41]; p < 0.00001), device-related embolism (RR 0.38 [0.23-0.60]; p < 0.0001), all-cause stroke (RR 0.75 [0.65-0.86]; p < 0.0001), ischemic stroke (RR 0.81 [0.69-0.96]; p = 0.01), major bleeding (RR 0.65 [0.53-0.81]; p < 0.0001), and all-cause mortality (RR 0.54 [0.37-0.78]; p = 0.001). DRT showed a directional but non-significant trend toward reduction (RR 0.33 [0.09-1.20]; p = 0.09). LOHS was not reliably estimable (I² = 87%). CONCLUSIONS: The Watchman FLX is associated with significantly superior safety and efficacy outcomes relative to the Watchman 2.5 across the principal clinical domains of transcatheter LAAO. These findings are observational and hypothesis-generating rather than definitive evidence of device superiority; all comparisons reflect temporal and contextual differences inherent to sequential device eras and should be interpreted with caution. These results support the design of prospective, contemporaneously enrolled comparative studies and may inform future guideline deliberations.