A randomized controlled trial led by Dr. M.J. Mack, published in the New England Journal of Medicine, showed that in patients with severe aortic stenosis and a low surgical risk, treatment with transcatheter aortic valve replacement (TAVR) with a balloon expandable valve was associated with a lower risk of stroke, death or rehospitalization by 1 year when compared to surgery.
The role of TAVR in the treatment of patients with severe aortic stenosis (AS) continues to evolve. Previously randomized trials showed that TAVR with both balloon expandable valves and self-expanding valves was either superior or non-inferior to surgery in patients with either a moderate or high risk of death with surgery. As TAVR techniques continue to develop, more patients have begun to undergo TAVR for the treatment of aortic valve replacement. However, a majority of patients requiring aortic valve replacement are at low surgical risk. Currently, there isn’t enough evidence supporting the use of TAVR in patients with a low risk of death after surgery. The PARTNER 3 trial was designed to address this knowledge gap.
“During the past decade, recommendations for TAVR in patients with severe, symptomatic aortic stenosis have been expanded to include strata with incrementally lower surgical risk. Current clinical practice has restricted the use of TAVR in patients who are at low risk and in younger patients, for whom surgery is standard therapy.” – Dr. M.J. Mack, M.D.
A total of 1,000 patients with severe aortic stenosis and a low risk of death were randomized to either TAVR with the SAPIEN 3 system or surgical aortic valve replacement. Surgical risk was assessed clinically and using the Society of Thoracic Surgeons Predicted Risk of Mortality score (<4% risk of death by 30 days). Patients with clinical frailty, bicuspid aortic valves or other features that increased the risk of complications associated with TAVR were excluded. The primary endpoint was the composite risk of death from any cause, stroke, or rehospitalization at 1 year after the procedure.
The assigned procedure was performed in 950 out of the 1,000 patients randomized. Of those 950 patients, 1-year data was available in 98.4% of patients. The composite outcome occurred in 42 patients in the TAVR group (8.5%) and 68 patients in the surgery group (15.1%) with a hazard ratio of 0.54 (95% CI 0.37 – 0.79, p = 0.001). Each component of the composite outcome was also assessed separately. Patients in the TAVR group had lower rates of death from any cause (1.0% vs 2.5%, HR 0.41, 95% CI 0.14 – 1.17), stroke (1.2% vs 3.1%, HR 0.41, 95% CI 0.15 – 1.00), and rehospitalization (7.3% vs 11.0%, HR 0.65, 95% CI 0.42 – 1.00). Additionally, 30-day outcomes were also evaluated. Patients in the TAVR group had lower rates of stroke (0.6% vs 2.4%, p = 0.02), lower rates of death or stroke (1.0% vs 3.3%, HR 0.30, p = 0.01), and new-onset atrial fibrillation (5.0% vs 39.5%, HR 0.10, p <0.001). TAVR also resulted in a shorter hospitalization after the procedure (3 days vs 7 days, p <0.001). Finally, patients who underwent TAVR had a faster improvement in the NYHA class, 6-minute walk-test distance and Kansas City Cardiomyopathy Questionnaire (KCCQ).
Despite the excellent surgical outcomes in both groups, patients in the TAVR group performed significantly better. However, transvalvular aortic-valve gradients were better in the surgical arm. When discussing the results of the study, Dr. Mack discussed the currently restricted indication for TAVR. He wrote, “During the past decade, recommendations for TAVR in patients with severe, symptomatic aortic stenosis have been expanded to include strata with incrementally lower surgical risk. Current clinical practice has restricted the use of TAVR in patients who are at low risk and in younger patients, for whom surgery is standard therapy.” However, with the results of this trial, as well as several other recently published randomized controlled trials, this may change. In an editorial published with the article, Dr. Catherine Otto discussed the need to change how aortic stenosis is viewed and treated. She stated, “It is time for a paradigm shift in how we approach decisions about valve type in patients with aortic stenosis. Estimated surgical risk no longer dictates the choice between surgery and TAVR; instead, the primary considerations are life expectancy and valve durability, both of which are related to the patient’s age.”