Effect of Device Size on Outcomes Following Left Atrial Appendage Closure in Borderline-Sized Anatomy

Selecting the optimal WATCHMAN FLX (a second-generation left atrial appendage [LAA] closure device) size for a borderline-sized LAA, for which 2 device sizes are acceptable, remains challenging.

The aim of this study was to evaluate how device size affects procedural and clinical outcomes in borderline-sized LAAs undergoing LAA closure.

From the Japanese multicenter TERMINATOR (Transcatheter Modification of Left Atrial Appendage by Obliteration with Device in Patients With NVAF) registry, 1,190 patients who underwent LAA closure with the second-generation device between May 2021 and September 2023 were reviewed. Of these, 757 with borderline-sized LAAs were included and categorized into large (n = 390) and small (n = 367) device groups. The median follow-up duration was 274 days (Q1-Q3: 100-368 days). Outcomes included peridevice leak (PDL), all-cause mortality, ischemic cerebrovascular accident or systemic embolism, major bleeding, and device-related thrombus.

PDL occurred less frequently in the large device group compared with the small device group (1.54% [6 of 390] vs 4.90% [18/367]; P = 0.015). Ischemic cerebrovascular accident or systemic embolism was lower in the large device group (8.4% [95% CI: 1.8%-34.1%] vs 10.5% [95% CI: 3.6%-28.4%]; P = 0.036). No significant difference was observed in all-cause mortality (15.2% [95% CI: 6.0%-35.7%] vs 12.3% [95% CI: 4.6%-30.6%]; P = 0.288), major bleeding (4.5% [95% CI: 2.6%-7.7%] vs 15.7% [95% CI: 4.3%-48.7%]; P = 0.570), or device-related thrombus (8.6% [95% CI: 3.2%-22.2%] vs 3.2% [95% CI: 1.6%-6.4%]; P = 0.603).

In borderline-sized LAAs, the larger device was associated with fewer PDLs and ischemic events without increased procedural risk.