Transcatheter aortic valve replacement (TAVR) is superior to medical therapy in inoperable patients with severe, symptomatic aortic stenosis (AS), and may be the preferred option in high-risk surgical patients. The comparative efficacy of TAVR and surgical aortic valve replacement (SAVR) in intermediate risk AS patients has been less well studied. The PARTNER 2 randomized trial showed non-inferiority of balloon expandable TAVR compared to SAVR in intermediate risk patients at 2 years. In the Surgical Replacement and Transcatheter Aortic Valve Implantation (SURTAVI) trial, a self-expandable TAVR prosthesis (Medtronic’s CoreValve [84%] and Evolut R [16%]) was randomized against SAVR in 1660 intermediate risk patients. The primary endpoint was a composite of death from any cause and disabling stroke at 24 months. The mean age was 79.8±6.2 years with an average Society of Thoracic Surgeons (STS) estimated risk of death of 4.5±1.6%. At 24 months, the TAVR group was non-inferior to the SAVR group for the primary endpoint (12.6% vs. 14.0%, posterior probability of non-inferiority, >0.999). Rates of both individual components of this endpoint were also similar. TAVR, compared to surgery was associated with lower rates of acute kidney injury (1.7% vs. 4.4%), atrial fibrillation (12.9% vs. 43.4%), and transfusion requirements (12.5% vs. 41.1%), but higher rates of residual aortic regurgitation (5.3% vs. 0.6%) and need for pacemaker implantation (25.9% vs. 6.6%).

Conclusions
While the trials migrate across risk spectrum and prosthesis type, short term outcomes with TAVR are equivalent to, if not better than, SAVR. Two large industry-sponsored randomized trials of TAVR vs SAVR in low surgical risk individuals are currently on-going and are sure to be scrutinized closely. Evidence for transcatheter valve durability remains a critical unknown that will need to be addressed prior to full-scale adoption of TAVR as first-line therapy in younger individuals.
Reardon MJ, Van Mieghem NM, Popma JJ, et al., for the SURTAVI Investigators. Surgical or Transcatheter Aortic-Valve Replacement in Intermediate-Risk Patients. N Engl J Med 2017;376:1321-31.

Enrique Zolezzi, James M McCabe

University of Washington, Division of Cardiology