Three-Year Data Presented From Medtronic Evolut Low Risk Trial of TAVR Versus SAVR

March 5, 2023—The American College of Cardiology (ACC) announced that the Evolut Low Risk trial demonstrated that the number of deaths and disabling strokes among patients at low surgical risk who were treated with transcatheter aortic valve replacement (TAVR) remained lower at 3 years postprocedure, but not significantly lower, compared with patients who received surgical aortic valve replacement (SAVR). The study was funded by Medtronic, manufacturer of the aortic valve replacement devices used in the trial.

The findings were presented by John K. Forrest, MD, at ACC.23/WCC, the ACC's annual scientific session together with the World Congress of Cardiology held March 4-6, 2023, in New Orleans, Louisiana. The study, "Three-Year Outcomes after Transcatheter or Surgical Aortic Valve Replacement in Low-Risk Patients with Aortic Stenosis," was simultaneously published by Dr. Forrest et al online in Journal of the American College of Cardiology.

Dr. Forrest commented in the ACC press release, "This study shows that the initial benefit of TAVR remained broadly consistent over the first 3 years. In patients who are at low risk for death, stroke, or other serious complications of aortic valve surgery, we need to have compelling evidence that TAVR is both safe and effective and also that the results are durable. The consistent benefit of TAVR at 3 years is not something that has been observed in prior studies and provides further evidence that TAVR deserves to be the dominant treatment modality for patients with aortic stenosis undergoing valve replacement." Dr. Forrest is director of interventional cardiology and structural heart disease at Yale University School of Medicine in New Haven, Connecticut.

The 2020 ACC/American Heart Association Guideline for the Management of Patients With Valvular Heart Disease recommends TAVR over SAVR for patients aged > 80 years and SAVR for patients aged < 65 years who have a life expectancy of > 20 years. The guideline was published in December 2020 in Journal of the American College of Cardiology (2021;77:e25–e197). It was also published in Circulation (2021;143:e72–e227).

For patients aged 65-80 years, noted Dr. Forrest, the guideline recommends that the choice of TAVR or SAVR be based on shared decision-making by the patient and their cardiologist.

As summarized in the ACC press release, the Evolut Low Risk trial enrolled 1,468 patients (median age, 74 years; 35% women) in seven countries (Australia, Canada, France, Japan, the Netherlands, New Zealand, and the United States). All patients had severe symptomatic aortic stenosis and were deemed to be at low risk from surgery, defined as having no more than a predicted 3% risk of death within 30 days of the procedure. Half of the patients were randomly assigned to receive TAVR and half to SAVR.

The study’s primary endpoint was a combination of death from any cause or a disabling stroke at 2 years. Secondary endpoints included (a) death from any cause, a disabling stroke, or readmission to the hospital for an aortic valve blockage; (b) the percentage of patients experiencing leakage of blood around the replacement valve or needing a permanent new heart pacemaker; and (c) improvement in patients’ quality of life.

ACC noted that in May 2019, findings from a prespecified interim analysis conducted after a median follow-up period of 12.2 months was published by Jeffrey J. Popma, MD, et al in The New England Journal of Medicine (2019;380:1706-1715).

That analysis estimated statistically that 5.3% of patients in the TAVR group would experience the primary endpoint within 24 months, compared with 6.7% in the SAVR group, suggesting that TAVR was noninferior to SAVR at 2 years.

ACC reported that in the current study presented at ACC.23, all patients have been followed for at least 3 years. The investigators found that 7.4% of patients treated with TAVR had died or had a disabling stroke versus 10.4% of patients treated with SAVR, a difference that fell just short of statistical significance. Occurrence of the secondary combined endpoint of death from any cause, a disabling stroke, or readmission to the hospital for an aortic valve blockage was significantly lower for the TAVR group than the SAVR group (13.2% vs 16.8%).

More patients in the TAVR group than the SAVR group experienced mild leakage of blood around the replacement heart valve (20.3% vs 2.5%); however, this finding was not associated with an increase in deaths or disabling stroke. In addition, compared with SAVR patients, more TAVR patients needed permanent new heart pacemakers (9.1% vs 23.2%).

In both groups, approximately 1% of patients needed a repeat aortic valve replacement procedure and < 1% experienced a blood clot on the replacement valve. At 30 days postprocedure, TAVR patients reported greater improvement in quality of life compared with SAVR patients; however, at 3 years both groups reported similar improvements in quality of life.

In addition to being deemed low risk for death or a stroke after surgery, patients enrolled in the study were also required to have "favorable anatomy" for TAVR, Dr. Forrest said. For example, patients with large, bulky calcium deposits in the aortic valve or other disease features that increased the likelihood of TAVR failure were excluded from the study.

Since the Evolut Low Risk trial was completed, the replacement valves evaluated in the trial have been replaced by a new generation of devices that have been shown to reduce leakage of blood around the replacement valve, noted Dr. Forrest said. Additionally, he said, higher incidence of new pacemaker placement remains a risk for TAVR patients receiving certain types of replacement aortic valves.

Although the current study’s findings are largely reassuring, longer-term data for low-risk patients are still needed and patients enrolled in the study will be followed for 10 years, advised Dr. Forrest in the ACC press release.

Dr. Forrest concluded, "Patients with severe aortic stenosis who are at low surgical risk should continue to engage in shared decision-making with their physicians concerning the risks and benefits of surgical versus transcatheter valve replacement."