ABSTRACT: Importance:Moderate/severe and even mild paravalvular regurgitation (PVR) are associated with increased mortality following transcatheter aortic valve replacement (TAVR) with first and second generations of transcatheter valves. Objective:To examine the incidence, evolution, and effect on 1-year outcomes of PVR following TAVR with a third-generation balloon-expandable transcatheter heart valve. Design, Setting, and Participants:Prespecified analysis of PVR in the Placement of Aortic Transcatheter Valves (PARTNER) II SAPIEN 3 trial, conducted between October 1, 2013, and September 3, 2014. Multicenter, nonrandomized registry of 1661 patients at intermediate or high surgical risk undergoing TAVR with the SAPIEN 3. Patients with severe, symptomatic aortic stenosis and high/intermediate surgical risk were enrolled in the registry at 51 sites in the United States and Canada. Interventions:Transcatheter aortic valve replacement with the SAPIEN 3 valve. Main Outcomes and Measures:Paravalvular regurgitation was assessed in a core laboratory at 30 days and 1 year according to a 5-class scheme: 0, none or trace; 1, mild; 2, mild to moderate; 3, moderate; 4, moderate to severe; and 5, severe. We assessed the effect of PVR on 1-year mortality and heart failure rehospitalization. Results:Among the 1661 included in the registry, 1592 received a SAPIEN 3 valve and had assessment of PVR. Of these patients, 55.7% had none-trace PVR, 32.6% had mild, 8.2% had mild to moderate, and 3.5% had at least moderate PVR at 30 days. At 1 year, 9.3% of patients had died and 14.2% had been rehospitalized. Only patients with at least moderate PVR had higher 1-year mortality (hazard ratio [HR], 2.40; 95% CI, 1.30-4.43; P?=?.005) and composite of mortality/rehospitalization (HR, 2.35; 95% CI, 1.52-3.62; P?