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.