At Low Surgical Risk: A Review of TAVR in Low-Risk Patients
Aditya Sengupta, MD; Sophia L. Alexis, MD; Gilbert H. L. Tang, MD, MSc, MBA
This past decade has witnessed the evolution of Transcatheter Aortic Valve Replacement (TAVR) as the preferred treatment for symptomatic severe aortic stenosis in patients who are at an intermediate, high, or extreme risk for surgery. Four landmark clinical trials now provide strong evidence that TAVR is non-inferior, and perhaps even superior, to surgery at short- and mid-term follow-up. However, issues such as new-onset left bundle branch block and permanent pacemaker implantation continue to plague outcomes after TAVR, and the long-term durability of the implanted bioprostheses have yet to be determined before TAVR can be universally adopted.
Since its first clinical application in 2002, Transcatheter Aortic Valve Replacement (TAVR) has evolved dramatically and has surpassed Surgical Aortic Valve Replacement (SAVR) as the standard of care for patients with severe symptomatic aortic stenosis who are at an intermediate or higher risk for surgery.[1-12] Trial data now suggest that TAVR with a balloon-expandable or self-expanding transcatheter heart valve (THV) is at least as safe and effective as SAVR in patients at low surgical risk.[13-16] Here, we critically assess the data from the recent low-risk TAVR studies in the context of its evolving clinical indications. Outstanding issues, including long-term adverse events and durability, are also discussed.
Landmark Low-Risk Trials
Four landmark trials comparing TAVR with SAVR in patients at low surgical risk are discussed below (Table 1).
The results of four landmark low-risk trials are summarized here. AF = Atrial Fibrillation; AKI = Acute Kidney Injury; AR = Aortic Regurgitation; BVF = Bioprosthetic Valve Failure; CI = Confidence Interval; HALT = Hypoattenuated Leaflet Thickening; HR = Hazard Ratio; NORDIC = Nordic Aortic Valve Intervention; PARTNER = Placement of Aortic Transcatheter Valves; PPM = Permanent Pacemaker; SAVR = Surgical Aortic Valve Replacement; STS-PROM = Society of Thoracic Surgeons-Predicted Risk of Mortality; SVD = Structural Valve Deterioration; TAVR = Transcatheter Aortic Valve Replacement; THV = Transcatheter Heart Valve.
The PARTNER 3 & Evolut Low-Risk Trials
The Placement of Aortic Transcatheter Valves (PARTNER) 3 Trial evaluated the noninferiority and superiority of the Edwards SAPIEN 3 THV (N = 503) versus SAVR (N = 497) in low-risk patients (Society of Thoracic Surgeons Risk of Mortality, or STS-PROM, <4%). The composite endpoint of death from any cause, stroke, or re-hospitalization at one year was significantly lower with TAVR. While the vast majority of the 30-day safety end points were similar between the two treatment arms, the rates of new-onset atrial fibrillation (AF) at 30 days, death or stroke at 30 days, and length of hospitalization were significantly lower with TAVR.
Similarly, the Evolut Low-Risk Trial tested the non-inferiority of the Medtronic self-expanding THV (N = 725) against surgery (N = 678) in low-risk patients. Here, three different self-expanding prostheses were used for TAVR due to their availability during the study period (CoreValve, Evolut R, or Evolut PRO). Compared to the PARTNER 3 trial, this study had a longer follow-up period of two years with regards to the composite primary endpoint of death or disabling stroke (5.3% vs. 6.7%, posterior probability > 0.999 for noninferiority). Furthermore, at 30 days, TAVR patients had a lower incidence of AF and life-threatening bleeding, but a higher incidence of at least moderate aortic regurgitation (AR).
To read the full article, please go to the October 2019 Issue of CCT.