SURTAVI: five-year results from a randomized trial of TAVR vs. SAVR in patients at intermediate surgical risk

Reported from TCT 2021

Why this study – the rationale/objective?

Although transcatheter aortic-valve implantation (TAVI) is an accepted alternative to surgery in patients with severe aortic stenosis who are at high surgical risk, less is known about long-term comparative outcomes among patients with aortic stenosis who are at intermediate surgical risk.

At 5-year follow-up, TAVI procedures performed with balloon-expandable prostheses compared to surgical aortic valve replacement (SAVR), in the context of patients at intermediate surgical risk, were associated with similar hemodynamic performances, although with higher rates of readmission.

How was it executed – the methodology?

The SURTAVI trial is a multinational, randomized, noninferiority clinical trial designed to compare the safety and efficacy of TAVI (performed with a self-expanding prosthesis) and surgery in patients with symptomatic, severe aortic stenosis at intermediate surgical risk (Risk of Operative Mortality ≥ 3 % to < 15 %), with the risk profile determined by a multidisciplinary Heart Team.

• Patients were pre-stratified for revascularization before randomization
• A total of 1,746 patients underwent randomization at 87 centres. In the MITT arm, 864 patients were in the TAVI cohort (mean age was 79.9 ± 6.2 years; STS-PROM 4.4 ± 1.5 %) and 796 were in the surgical cohort (mean age was 79.7 ± 6.1 years; STS-PROM 4.5 ± 1.6 %)
• In the majority of cases, was used the Corevalve bioprosthesis (1^st generation; 84 %), while in the reminder, the Corevalve Evolut R (2^nd generation; 16 %) was implanted
• Serious adverse events were adjudicated by a clinical events committee following the VARC definitions
• Iliofemoral was the preferred vascular access (93.6 %)
• Echocardiographic outcomes at baseline, discharge, and at the 1,2 and 5-year follow-up were assessed by a core laboratory
• Key clinical outcomes were the following:
  • All-cause mortality or disabling stroke (primary endpoint);
  • valve durability (core-laboratory assessed echocardiography, endocarditis, and thrombosis);
  • Valve-related reinterventions and rehospitalizations;
  • Quality of life
• Primary analysis relayed on modified intention to treat (MITT) cohort (defined as undergoing an attempt implant of the assigned therapy)
• Comparisons of adverse events were performed with log-rank test and reported as Kaplan-Meier estimates. Key outcomes between 2 and 5 years were assessed by using a post hoc landmark analysis

What is the main result?

The 2-year results of the trial were previously reported (Reardon et al. NEJM 2017). In brief, the 2-year rate of all-cause death or disabling stroke was 12.6  % in patients who underwent TAVI and 14.0 % with surgery, a difference that met the criteria for noninferiority. However, TAVI was associated with elevated rates of major vascular complications (6.0 % vs 1.1 %), pacemaker implantation (25.9 % vs 6.6 %), and moderate or severe residual paravalvular regurgitation was more common following (5.3 % vs 0.6 %), compared to surgery.

• In the SURTAVI 5-year, the follow-up was available for 93.7 % of patients in the TAVI arm, and 95.5 % of patients in the surgical arm, with around 50 % of the population presenting with frailty features at baseline.
• There was no difference in the rate of all-cause mortality or disabling stroke between the TAVI and SAVR arms at 5 years (31.3 % vs 30.8 %; HR 1.02; 95 % CI 0.85-1.22)
• In terms of clinical outcomes, no differences were observed between the two cohorts in terms of death, stroke, and myocardial infarction. However, the TAVI arm showed a significantly higher rate of pacemaker compared to surgery (35.8 % vs. 14.5 %; p < 0.001)
• Compared to the 2-year follow-up results of SURTAVI, showing significant differences between TAVI and surgery in the rates of reintervention (2.5 % vs. 0.5 %; p = 0.002) and a trend toward higher rates of hospitalization for heart failure (12.8 % vs. 9.5 %; p = 0.06), the post hoc landmark analysis performed between 2 and 5 years showed a low rate of reintervention (TAVI 1.0 % vs. SAVR 1.3 %; p = 0.60) and heart failure hospitalizations (TAVI 12.7 % vs. SAVR 12.5 %; p = 0.60), without significant differences between the two arms.
• The 5-year echocardiographic data about hemodynamic showed TAVI provided larger effective orifice areas (2.2 cm² vs. 1.8 cm²) and lower mean gradients (8.6 mmHg vs. 11.2 mmHg) compared with surgery at each follow-up time point through 5 years (P < 0.001 for all). However, they had significantly less ≥ mild aortic regurgitation or paravalvular leaks at each time point of the follow-up (P < 0.001 for all).
• Finally, at the 5-year follow-up, there were no differences in terms of quality of life as assessed by KCCQ and NYHA.

Critical reading and relevance for clinical practice

Interventional cardiologist's perspective

Overall, these results confirm and extend the favourable outcomes of TAVI, in terms of key clinical endpoints, up to 5 years from the index procedure, with similar outcomes between percutaneous and surgical treatments after two years.

The present analysis presents reassuring data with respect to durability of TAVI with self-expandable prostheses both in terms of forward-hemodynamics and clinical outcomes, answering one of the most prominent concerns that emerged when the 2-year follow-up results were published.

The data from the 5-year follow-up of the SURTAVI trial support the safety and effectiveness of percutaneous valve implantation in elderly patients, down to 80 years old, at intermediate surgical risk presenting with severe symptomatic aortic stenosis.

Of note, these results appear in line with the 5-year data from the PARTNER 2A trial showing similar outcomes with TAVI using a balloon-expandable valve and surgery in patients with a similar risk profile.

In routine clinical practice, the treatment of choice will always require a joint discussion of the Heart Team. However, in light of the SURTAVI results, the added value of a less-invasive therapy with a faster recovery makes TAVI treatment appealing in such an elderly population, making it a reasonable option for the majority of patients.

As a note of caution, in patients with longer life expectancy, the higher rates of permanent pacemaker implantation (35.8 % vs. 14.5 %; p < 0.001) and ≥ mild paravalvular leaks (30.1 % vs. 3.4 %, p < 0.001) showed in the TAVI arm compared to surgery, appear not negligible aspects to take into consideration. This is particularly true in light of the accumulating evidence showing moderate-to-severe paravalvular regurgitation does have a detrimental impact on outcomes, warranting improvements in device technologies and sizing techniques.

 

Cardiac surgeon's perspective

5-year results of the SURTAVI trial demonstrated that there is no significant difference between TAVI and SAVR in all-cause mortality or disabling stroke. Nevertheless, several other factors must be taken into account.

At 5 years, 27 % of SAVR patients, either were lost to follow-up or withdrew from the study, vs 11 % of TAVI patients. This bias may considerably affect the results, favouring TAVI instead of SAVR.

Surgery proved to be significantly better than the transcatheter approach in relation to some secondary endpoints:

• Pacemaker implantation rate (14.6 % SAVR vs 35.8 % TAVR, p < 0.001)
• More-than-mild paravalvular leak or aortic regurgitation (all p < 0.001 in favour of surgery)

Both factors may worsen prognosis in the long term, as already described in the literature, and this must be considered in the case of patients younger than 80 years old (mean age of this study).

Only hemodynamical data was significantly better in TAVI at 5 years: mean gradient was lower (8.6 mmHg vs 11.2 mmHg in SAVR group), and effective orifice area was wider (2.2 cm2 vs 1.8 cm2). Trends of these parameters were similar and constant over time for both groups.

Furthermore, no differences were detected for rehospitalization, NYHA class, and Kansas City Cardiomyopathy Questionnaire. Valve thrombosis and endocarditis occurred in a low percentage of patients in both groups (valve thrombosis: 0.5 % TAVI vs 0.4 % SAVR, p = 0.51; endocarditis: 1 % TAVI vs 1.8 % SAVR, p = 0.15). No data were reported on medical therapy.

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