Left atrial appendage closure in patients with prohibitive anatomy: Insights from PINNACLE FLX

Background: Watchman 2.5 (Boston Scientific Inc, Marlborough, MA) implant success approaches 95% in registries, yet many patients are not attempted because of complex left atrial appendage (LAA) anatomy. Watchman FLX can expand the range of ostium width (14-31.5 mm) and depth available for LAA closure.

Objective: The purpose of this study was to evaluate the safety and efficacy of Watchman FLX in patients with a failed Watchman 2.5 attempt or prohibitive LAA anatomy.

Methods: The roll-in (n = 58) and primary effectiveness (n = 400) cohorts of the PINNACLE FLX trial comprised the study population. Subjects were identified who previously failed implantation of Watchman 2.5 (n = 11) or were not attempted because of prohibitive LAA anatomy (n = 88). Demographic characteristics, implant procedure details, and TEE follow-up data were compared to controls composed of enrollees not meeting these criteria (n = 359).

Results: Watchman FLX LAA closure was successfully implanted in all subjects with a prior failed Watchman 2.5 attempt (n = 11 of 11). Subjects with previously failed Watchman 2.5 were more likely to receive a 35 mm FLX device than controls (27.3% vs 7.3%; P = .047). Patients with prohibitive anatomy had smaller LAA dimensions than did controls (diameter 18.0 ± 4 mm vs 20.4 ± 3 mm; P < .001 and length 23.7 ± 5 mm vs 28.9 ± 5 mm; P < .001). There was no difference in age, sex, CHA₂DS₂-VASc score, HAS-BLED score, or primary efficacy between cohorts. Transesophageal echocardiography (TEE) at 12 months showed zero leak in 90.9% in the failed Watchman 2.5 cohort, 91.3% in the prohibitive anatomy cohort, and 89.5% in the control cohort (P = .84). Overall and cardiovascular mortality was lower in the prohibitive anatomy cohort (1.2% vs 8.8% in controls; P = .02).

Conclusion: Watchman FLX implantation in patients with a prior failed Watchman 2.5 attempt or prohibitive LAA anatomy remained safe and highly effective. The association of reduced overall mortality with smaller LAA dimension warrants future study.