Transcatheter Aortic Valve Replacement in Low-Risk Patients

ranscatheter aortic valve replacement (TAVR) has become the preferred therapy over surgical aortic valve replacement (SAVR) in intermediate-or greaterrisk patients with symptomatic severe aortic stenosis (AS).Results from the 2 randomized trials comparing TAVR with SAVR in low-risk patients have been reported.1,2 The PARTNER 3 trial (The Safety and Effectiveness of the SAPIEN 3 Transcatheter Heart Valve in Low Risk Patients With Aortic Stenosis [P3]) that evaluated the Sapien 3 (S3) valve (Edwards Lifesciences LLC) showed superiority of TAVR over SAVR at 1 year in the primary composite outcome of mortality, stroke, and rehospitalization related to the procedure, valve, or heart failure (8.5% versus 15.1%, P=0.001).The Evolut Low Risk trial (Medtronic Evolut Transcatheter Aortic Valve Replacement in Low Risk Patients [ELR]) that evaluated the Evolut valve (Medtronic Inc) showed the noninferiority of TAVR versus SAVR in the 2-year primary composite end point of mortality or disabling stroke (5.3% versus 6.7%).The 2 trials had similar patient characteristics, with mean age 74 years and the Society of Thoracic Surgeons predicted risk of operative mortality score 1.9% in both groups (Table).At 1 year, mortality rates were 1.0% TAVR versus 2.5% SAVR, P=0.09 in P3, and 2.3% versus 3.0%, log-rank P=0.41 in ELR.Disabling stroke rates trended lower with TAVR than with SAVR (0.2% versus 0.9%, P=0.14 in P3; 0.7% versus 2.4%, log-rank P=0.024 in ELR).In ELR, although no significant difference was found in the primary outcome, the composite outcome of mortality, disabling stroke, or heart failure hospitalization at 1 year showed that TAVR was superior (5.6% versus 10.2%, P=0.002).3 Thus, both trials showed that TAVR was superior to SAVR for clinical outcomes, with remarkable concordance between the 2 trials.Although both TAVR valves were associated with similar rates of new left bundle-branch block, the 1-year permanent pacemaker implantation rate was lower with S3 than Evolut (7.3% versus 19.4%), with differences likely attributed to device design and operator variability.The incidence of mild or greater paravalvular leak associated with S3 or Evolut valves was not different at 1 year (30.0% and 37.5%, respectively).Both TAVR devices had similarly low incidence of coronary obstruction, valve thrombosis, and aortic valve reintervention.However, S3 had a higher incidence of severe prosthesis-patient mismatch than Evolut (8.3% versus 1.1%), likely because of valve design and sizing differences.This difference may be clinically important given the previously reported higher 1-year mortality and heart failure hospitalization in patients with severe mismatch after TAVR (mortality: 17.2% in severe versus 15.6% in moderate versus 15.9% in none, P=0.02).With TAVR showing superiority over SAVR, how should we select the ideal treatment of low-risk patients with symptomatic severe AS?We believe both trials share certain conclusions but also raise new questions.First, in low-risk patients, SAVR has excellent outcomes but is limited by more new-onset atrial fibrillation than TAVR (at 1 year: 40.9% versus 7.0% in P3; 38.3% versus 9.8% in ELR).