BACKGROUND The PRAGUE-17 (Left Atrial Appendage Closure vs Novel Anticoagulation Agents in Atrial Fibrillation) trial demonstrated that left atrial appendage closure (LAAC) was noninferior to nonwarfarin direct oral anticoagulants (DOACs) for preventing major neurological, cardiovascular, or bleeding events in patients with atrial fibrillation (AF) who were at high risk. OBJECTIVES This study sought to assess the prespecified long-term (4-year) outcomes in PRAGUE-17. METHODS PRAGUE-17 was a randomized noninferiority trial comparing percutaneous LAAC (Watchman or Amulet) with DOACs (95% apixaban) in patients with nonvalvular AF and with a history of cardioembolism, clinically-relevant bleeding, or both CHA(2)DS(2)-VASc >= 3 and HASBLED >= 2. The primary endpoint was a composite of cardioembolic events (stroke, transient ischemic attack, or systemic embolism), cardiovascular death, clinically relevant bleeding, or procedure-/device-related complications (LAAC group only). The primary analysis was modified intention-to-treat. RESULTS This study randomized 402 patients with AF (201 per group, age 73.3 +/- 7.0 years, 65.7% male, CHA(2)DS(2)-VASc 4.7 +/- 1.5, HASBLED 3.1 +/- 0.9). After 3.5 years median follow-up (1,354 patient-years), LAAC was noninferior to DOACs for the primary endpoint by modified intention-to-treat (subdistribution HR [sHR]: 0.81; 95% CI: 0.56-1.18; P = 0.27; P for noninferiority = 0.006). For the components of the composite endpoint, the corresponding sHRs were 0.68 (95% CI: 0.39-1.20; P = 0.19) for cardiovascular death, 1.14 (95% CI: 0.56-2.30; P = 0.72) for all-stroke/transient ischemic attack, 0.75 (95% CI: 0.44-1.27; P = 0.28) for clinically relevant bleeding, and 0.55 (95% CI: 0.31-0.97; P = 0.039) for nonprocedural clinically relevant bleeding. The primary endpoint outcomes were similar in the per-protocol (sHR: 0.80; 95% CI: 0.54-1.18; P = 0.25) and on-treatment (sHR: 0.82; 95% CI: 0.56-1.20; P = 0.30) analyses. CONCLUSIONS In long-term follow-up of PRAGUE-17, LAAC remains noninferior to DOACs for preventing major cardiovascular, neurological, or bleeding events. Furthermore, nonprocedural bleeding was significantly reduced with LAAC. (C) 2022 by the American College of Cardiology Foundation.