Patient-Level Analysis of Watchman Left Atrial Appendage Occlusion in Practice Versus Clinical Trials

Objectives: The aim of this study was to compare outcomes among patients from the PROTECT-AF (WATCHMAN Left Atrial Appendage System for Embolic PROTECTion in Patients With Atrial Fibrillation) and PREVAIL (Evaluation of the WATCHMAN Left Atrial Appendage [LAA] Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy) left atrial appendage occlusion (LAAO) trials with matched patients from the National Cardiovascular Data Registry LAAO Registry using patient-level data.

Background: Patients undergoing LAAO in clinical practice generally have more comorbidities than trial participants.

Methods: Propensity-matched analyses, with up to 3 registry patients matched to each trial patient, were performed using Cox proportional hazards and Fine-Gray models.

Results: A total of 1,904 registry patients were matched to 667 trial LAAO patients; 1,010 registry patients were matched to 348 warfarin patients. Compared with registry patients, trial LAAO patients experienced more pericardial effusion requiring intervention (3.8% vs 0.6%, P < 0.001), periprocedural ischemic stroke (0.9% vs 0.2%, P = 0.005), and failed device implantation (7.5% vs 3.6%, P < 0.001). The 425-day risk of ischemic stroke in trial LAAO patients was higher than in registry patients (2.70% vs 1.21%; HR: 1.951; P = 0.03); warfarin patients had comparable rates of ischemic stroke compared with registry patients (1.15% vs 1.29%; HR: 0.728; P = 0.57). Hemorrhagic stroke risk was similar among trial LAAO and registry patients (P = 0.88). Hemorrhagic stroke risk was greater among warfarin patients versus registry patients (1.44% vs 0.20%; HR: 5.871, P = 0.03). Mortality was lower in trial LAAO patients than in registry patients (2.92% vs 6.23%; HR: 0.477; P = 0.004), a difference attributable to noncardiovascular deaths. Mortality was similar (P = 0.44) among trial warfarin (4.48%) and registry (5.86%) patients.

Conclusion: In clinical practice, patients who meet trial criteria and undergo LAAO experience a lower risk of ischemic stroke, a similar risk of hemorrhagic stroke, and a higher risk of death after implant versus LAAO trial patients. (WATCHMAN Left Atrial Appendage System for Embolic PROTECTion in Patients With Atrial Fibrillation [PROTECT-AF], NCT00129545; Evaluation of the WATCHMAN Left Atrial Appendage [LAA] Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy [PREVAIL], NCT01182441).