PARTNER 3: New Studies Shed Light on Long-Term Outcomes of TAVR vs. SAVR in Low-Risk Patients With Severe AS

There was no significant between-group difference in the composite of death, stroke or rehospitalization at five years in patients who were at low surgical risk with severe, symptomatic aortic stenosis who underwent either TAVR or surgery, based on new findings from the PARTNER 3 trial presented Oct. 24 during TCT 2023 and simultaneously published in the New England Journal of Medicine. Similarly, no significant differences were observed in the hierarchical composite that included death, disabling stroke, nondisabling stroke, and the number of rehospitalization days.

Under the PARTNER 3 trial, a total of 1,000 patients were randomly assigned to either TAVR or surgery. A total of 948 patients (495 in the TAVR group and 453 in the surgery group) received the intended valve. A previous analysis of data after one year, found a significantly lower composite endpoint of death, stroke or rehospitalization with TAVR compared with surgery. This new analysis compares the two primary endpoints from the one-year analysis, and also assesses hemodynamic performance and incidence of bioprosthetic-valve failure at five years.

In presenting the findings, Martin B. Leon, MD, FACC, said that a component of the first primary endpoint – death, stroke or rehospitalization – occurred in 111 of the patients in the TAVR group (22.8%) compared with 117 of the patients (27.2%) in the surgery group. The win ratio for the second primary endpoint (the hierarchical composite of death, stroke and number of rehospitalization days) was 1.17 (95% CI, 0.90 to 1.51; p=0.25). According to Leon, the incidence of stroke at five years, while low, still remains one of the most serious complications of aortic-valve replacement.

In other findings, Leon highlighted the importance of valve durability, especially in younger patients, and noted no significant difference in hemodynamic valve performance and the incidence of bioprosthetic-valve failure between the TAVR and surgery groups at five years. Specifically, the hemodynamic performance of the valve was 12.8 ± 6.5 mm Hg in the TAVR group and 11.7 ± 5.6 mm Hg in the surgery group, while bioprosthetic-valve failure occurred in 3.3% of patients in the TAVR group compared with 3.8% of patients in the surgery group.

“Hemodynamic valve performance of both TAVR and surgical valves seemed to be similar to that reported previously at two years,” said the study authors. “The incidence of bioprosthetic-valve failure and of the need for reintervention was similar in the two groups at five years; these results are consistent with reported findings in intermediate-risk patients.”

In a separate late-breaking TCT 2023 study, Rebecca T. Hahn, MD, FACC, and Philippe Pibarot, DVM, PhD, FACC, shared results from their PARTNER 3 analysis comparing echocardiographic findings at five years, as well as examining any associations between 30-day echocardiographic parameters in the PARTNER 3 trial and clinical outcomes at five years.

In the 79% of PARTNER 3 patients available for the echocardiographic analysis, Hahn, Pibarot and colleagues observed sustained improvement over the five years in mean transaortic gradient and aortic valve area, among both the TAVR and surgery groups. While there was no significant difference in left ventricular remodeling between the two groups, researchers did note significantly lower tricuspid annular plane systolic excursion (TAPSE) and RV-PA coupling, with greater incidence of mild tricuspid regurgitation, among patients in the surgery group. Additionally, a significant association between the composite primary endpoint of death, stroke or rehospitalization and valvulo-arterial impedance (Zva) was also observed across both groups, with researchers noting this trend was largely driven by rehospitalization. 

“In patients treated with TAVR or surgery, post-intervention Zva and RV-PA coupling are associated with worse five-year outcomes,” said Hahn and Pibarot. “Parameters of ventricular/valvular/arterial coupling, such as Zva or TAPSE, should be considered as key endpoints to compare different types of aortic valve replacement in future [clinical trials], and should be considered in clinical practice to enhance risk stratification and therapeutic decision-making.”

Clinical Topics: Noninvasive Imaging, Echocardiography/Ultrasound, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease

Keywords: Transcatheter Cardiovascular Therapeutics, TCT23, Echocardiography, Stenosis, Aortic Disease

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