Trials have demonstrated that transcatheter aortic valve replacement (TAVR) results in similar mortality and lower risk of major bleeding and atrial fibrillation but higher risk of vascular complications for patients with severe, symptomatic aortic stenosis at intermediate or high surgical risk compared to surgical (open) aortic valve replacement (SAVR). However, no randomized trials have compared the two interventions in low surgical risk patients.

The PARTNER 3 trial is a randomized trial comparing TAVR versus SAVR among patients at low surgical risk. A thousand patients with severe, symptomatic aortic stenosis with a low risk of surgical mortality defined using the Society of Thoracic Surgeon Predicted Risk of Mortality (STS-PROM) calculator were randomized to open SAVR or TAVR. The protocol defined low-risk as an STS-PROM score of less than four percent surgical mortality at 30 days, a cut-off that was increased from two percent midway through the trial. Notably, patients with an ejection fraction less than 30 percent were excluded from the trial. Patients had an average age of 73 and average STS-PROM score of 1.9 percent. The TAVR group had more participants with New York Heart Association (NYHA) III or IV heart failure (31.2 percent vs. 23.8 percent). The non-inferiority margin for the primary composite endpoint of death, stroke, or rehospitalization at one year was set at six percent difference between the two groups. A significantly higher number of patients randomized to SAVR dropped out of the trial (seven patients vs. 43 patients), leaving 496 in the TAVR arm and 454 in the SAVR arm.

Evidence is accumulating in support of less invasive approaches to managing aortic stenosis.

In a per-protocol analysis, the rate of death, stroke, or rehospitalization was 8.5 percent in the TAVR group vs.15.1 percent in the SAVR group, meeting the non-inferiority margin. In a prespecified, superiority analysis, there was a statistically significant reduction in the primary endpoint in the TAVR group vs. the SAVR group (hazard ratio 0.54, 95% CI 0.37-0.79). An intention-to-treat sensitivity analysis met both the prespecified non-inferiority and superiority margins for the primary composite outcome. There were fewer adverse events and complications in the TAVR group compared to the SAVR group. Patients in the TAVR group had lower rates of major bleeding requiring transfusion and atrial fibrillation requiring a new medication, shorter hospital stays, and higher rates of discharge home.

While the findings of this trial may be difficult to generalize due to its strict inclusion criteria and industry influence in recruitment, design, and analysis, evidence is accumulating in support of less invasive approaches to managing aortic stenosis. This trial demonstrates that among patients with a low risk of mortality, TAVR reduces the risk of death, stroke, and rehospitalization at one year while also reducing complications from surgical intervention. With the addition of this trial, a minimally invasive approach should be offered to patients of all risk categories with severe, symptomatic aortic stenosis.

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