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Long-term outcomes and valve durability


Background

Early data for transcatheter aortic valve implantation (TAVI) was limited to inoperable and high surgical risk patients and as such the life span of the implanted prosthesis may be expected to exceed the life expectancy of these high-risk recipients. This has limited the data on longer-term outcomes available to date. In recent years, as TAVI has been expanded as a treatment option for both intermediate and low-risk patients, there is a heightened interest in valve durability and how these percutaneous options for patients with aortic stenosis (AS) compare with surgical aortic valve replacement (SAVR).

Long-term outcomes after TAVI in aortic stenosis

In all patient cohorts with degenerative AS, TAVI has been shown to be feasible (procedural success rates >90%) with outcomes that are not inferior to SAVR. Over the past two decades the combination of increased heart team expertise, better preprocedural imaging workup of the patients, and technical improvements of valves and delivery systems has led to gradual improvements in results with regard to early mortality and complication rates. Despite this, there are still some concerns on the long-term effectiveness of TAVI compared with SAVR, which are summarized in Fig. 16.1 . The key patient-focused outcomes after TAVI are as follows:

  • Whereas the 30-day mortality rate ranged from 5% to 15% in earlier reports, it has come down to 0.4% to 0.5% in the most recent studies of last-generation devices in low-risk population. In large registry data, all-comers 30-day mortality has reduced from 7.2% (2011) to 2.5% (2019).

  • Stroke is one of the most feared complications aftert TAVI, and rates have declined in recent years. Registry data suggest that in-hospital stroke rates have decreased slightly from 2.1% (2012) to 1.6% (2019), which may represent the gradual reduction in patient risk profile as the rate of stroke seen in high-risk patients has remained consistent (2.7%). A recent meta-analysis of clinical trials reported that TAVI is associated with a 19% lower risk of stroke compared with SAVR through 2 years.

  • Although the risk of mortality and stroke is broadly comparable between balloon-expandable and self-expandable valves, there is a marked difference in outcomes with regard to the need for new permanent pacemaker insertion in randomized studies. These rates have consistently been higher with self-expandable valves, and the most recent data suggest a rate of 17% in low-risk patients whereas pacemaker rates using balloon-expandable valves have consistently been under 10%.

  • Paravalvular regurgitation had been common, although it was reported to be trace or mild in the majority of patients and rarely clinically relevant; more than mild aortic regurgitation (AR) has an impact on long-term survival. This remains a concern and requires careful further follow-up and critical evaluation. In registry data, the incidence of greater than moderate AR at 30 days after implantation has fallen from 8.0% (2012) to 1.6% (2019).

  • Registry data from the Society of Thoracic Surgeons (STS)-American College of Cardiology (ACC) transcatheter valve therapy (TVT) Registry confirms this improvement in quality of life in a real-world setting with an improvement in Kansas City Cardiomyopathy Questionnaire (KCCQ) Score at 1 year from baseline across all surgical risk categories in patients undergoing TAVI. Interestingly, it is the low-risk patients that demonstrate the greatest improvement in KCCQ Score after TAVI.

Fig. 16.1, Issues Concerning Long-Term Outcomes After TAVI.

Outcomes from landmark randomized clinical studies

TAVI has been extensively investigated in a sequence of randomized clinical trials using both balloon-expandable and self-expanding devices in patients with symptomatic severe AS across the entire risk spectrum. A summary of the major outcomes after TAVI in large, randomized studies up to 5 years is shown in Table 16.1 . Next is a brief description of the landmark studies with the major findings highlighted.

TABLE 16.1
Overview of Current Patient Profiles and Outcomes of TAVI in Randomized Clinical Trials
Partner A Partner B Partner 2 Partner 3 CoreValve™ Surtavi Notion Trial Evolut Low Risk
n 348 179 1011 496 394 879 145 725
Age (years) 83.6 ± 6.8 83.1 ± 8.6 81.5 ± 6.7 73.3 ± 5.8 83.2 ± 7.1 79.9 ± 6.2 79.2 ± 4.9 74.1 ± 5.8
Female (%) 42.2 54.2 45.8 32.5 46.4 42.2 46.2 36.0
STS score (%) 11.8 11.6 5.8 ± 2.1 1.9 ± 0.7 7.3 ± 3 4.4 ± 1.5 2.9 ± 1.6 1.9 ± 0.7
30-day mortality (%) 3.4 5.0 3.9 0.5 3.3 2.2 2.1 0.5
30-day stroke (%) 3.8 6.7 5.5 0.6 4.9 3.4 1.4 3.4
New-onset pacemaker implantation (%) 4.4 3.4 8.5 6.5 19.8 25.9 34.1 17.4
1-year mortality (%) 24.3 30.7 12.3 1.0 14.2 6.7 4.9 2.4
2-year mortality (%) 33.9 43.3 16.7 2.4 22.2 11.4 8.0 —
5-year mortality (%) 67.8 71.8 46.0 — 55.5 31.3 27.6 —
STS , Society of Thoracic Surgeons.

PARTNER I (SAPIEN, prohibitive/high risk)

The Edwards SAPIEN balloon-expandable valve system was used for TAVI in this trial. The primary endpoint was all-cause death at 1 year. The PARTNER I trial consisted of two randomized cohorts:

  • Cohort B randomly assigned inoperable patients to either conservative treatment or transfemoral TAVI.

  • Cohort A randomly assigned high-risk patients to either transfemoral/transapical TAVI or SAVR.

In cohort B:

  • TAVI was associated with a 20% absolute risk reduction of all-cause death compared with conservative treatment at 1 year.

  • The follow-up data reported up to 5 years showed TAVI to maintain superiority over medical treatment.

In cohort A:

  • At 1-year follow-up TAVI was noninferior to SAVR in terms of all-cause death.

  • At 5-year follow-up:

    • The risk of all-cause death remained similar between TAVI and SAVR.

    • There was no difference in mortality between transfemoral TAVI and SAVR, whereas transapical TAVI was associated with a numerically higher risk of mortality compared with SAVR.

    • The risks of repeat hospitalization, stroke, and myocardial infarction, as well as functional status, were comparable between the groups.

US CoreValve high risk (CoreValve, high risk)

The US CoreValve High Risk trial compared TAVI by means of the CoreValve self-expanding valve system with SAVR in high-risk patients.

  • At 1-year follow-up TAVI was associated with a significantly lower risk of all-cause death than SAVR.

  • At 5-year follow-up:

    • Both TAVI and SAVR resulted in similar survival outcomes.

    • The risks of repeat hospitalization, major stroke, and myocardial infarction, as well as functional status, were comparable between the groups.

PARTNER II (SAPIEN XT, intermediate risk)

In the PARTNER II trial, intermediate-risk patients were randomized to TAVI using the SAPIEN XT balloon-expandable valve system or SAVR. Patients were stratified in cohorts according to access route (transfemoral or transthoracic) before the randomization. The primary endpoint was the composite of all-cause death or disabling stroke.

  • At 2-year follow-up:

    • TAVI was noninferior to SAVR in terms of the primary endpoint.

    • In the transfemoral access cohort, TAVI resulted in a lower rate of death or disabling stroke than SAVR.

    • In the transthoracic access cohort, outcomes were similar between the two groups.

  • At 5-year follow-up:

    • There was no significant difference in the primary endpoint between the TAVI group and the SAVR group.

    • This was driven by similar results for the transfemoral-access cohort compared with SAVR.

    • The risk of all-cause death or disabling stroke was higher after transthoracic-access TAVI than after SAVR.

    • Improvements in health status (New York Heart Association class and KCCQ-OS score) were also similar.

    • More patients in the TAVI group than in the SAVR group had aortic-valve reintervention and repeat hospitalization.

Surtavi (CoreValve/Evolut R, intermediate risk)

The SURTAVI trial was a randomized trial designed to compare the safety and efficacy of TAVI using the CoreValve or the Evolut R self-expanding valve system and SAVR in intermediate-risk patients. For the TAVI procedure, transfemoral access was preferred. The primary endpoint was the composite of all-cause death or disabling stroke at 2 years.

  • At 1-year follow-up:

    • TAVI was noninferior to SAVR for the primary endpoint. Each procedure was associated with different adverse events:

      • ■

        TAVI group: higher moderate or severe paravalvular leak (PVL) and need for new permanent pacemaker implantation (PPI)

      • ■

        SAVR group: higher rates of acute kidney injury and atrial fibrillation

  • At 2-year follow-up there were no differences in terms of all-cause death, major stroke, or myocardial infarction.

  • At 5-year follow-up, there were no differences in all-cause mortality or stroke, but there was higher reintervention in the TAVR group (3.5% vs. 1.9%), with associated increased rates of moderate to severe PVL. However, for the first time, TAVR demonstrated improved hemodynamic performance compared with SAVR (mean gradient: 8.6 vs. 11.2 mm Hg [ p < 0.001]; effective orifice area: 2.2 vs 1.8 cm 2 [ p < 0.001]).

PARTNER III (SAPIEN 3, low risk)

The PARTNER III trial was a randomized trial that compared transfemoral TAVI using the SAPIEN 3 balloon-expandable valve system with SAVR in low-risk patients. The primary endpoint was the composite of all-cause death, any stroke, or repeat hospitalization at 1 year.

  • At 30-day follow-up:

    • TAVI resulted in lower rates of stroke and new-onset atrial fibrillation than SAVR.

    • There were no significant between-group differences in major vascular and new PPI.

    • The incidence of moderate or severe PVL was low and not statistically different between the groups.

    • The percentage of severe prosthesis-patient mismatch at 30 days was low and similar between the groups.

  • At 1-year follow-up the rate of the primary endpoint was lower in the TAVI group than in the SAVR group; these benefits were maintained at 2-year follow-up.

Evolut low risk (CoreValve/Evolut R/PRO, low risk)

In the Evolut Low Risk trial, low-risk patients were randomized to TAVI or SAVR. TAVI was performed with the CoreValve, Evolut R, or Evolut PRO self-expanding valve systems. Transfemoral access was the default strategy (99.0%). The primary endpoint was the composite of all-cause death or disabling stroke at 2 years.

  • At 30-day follow-up:

    • TAVI resulted in a lower incidence of disabling stroke, bleeding complications, acute kidney injury, and new-onset atrial fibrillation compared with SAVR.

    • Using the self-expanding device, the rates of new PPI were higher in the TAVI group than in the SAVR group.

    • Severe prosthesis-patient mismatch occurred at 1 year in 1.8% of the TAVI group and in 8.2% of the SAVR group.

  • At 2-year follow-up TAVI was noninferior compared with SAVR in terms of the primary endpoint.

Long-term risk of stroke after TAVI

Stroke is a well-documented complication in the early period after TAVI, with 30-day stroke rates spanning between 1.0% and 5.5% in contemporary studies, and 1-year stroke rates spanning between 4.3% and 8.2%. Recent data have been published with medium-term outcomes with 5-year follow-up: the rates of stroke were similar between TAVI and SAVR in the PARTNER II population (odds ratio [OR] 1.2 [0.95–1.50]) and in the CoreValve High Risk participants (17.5% vs. 21.0%, P = 0.13).

In the longer term, little is known about the impact of treatment with TAVI on the risk of developing a stroke. Recent data from SWENTRY (SWEdish traNscatheter cardiac intervention regisTRY) found an annual stroke risk between 2.0% and 3.1% after TAVI compared with an age- and sex-matched cohort annual stroke risk of between 1.5% and 1.9% when patients were followed through 8 years postprocedure. Although there is numerically a higher risk of stroke after TAVI than seen in the general population, this may be due to an increased frequency of predisposing risk factors seen in patients undergoing TAVI (i.e., diabetes, history of prior stroke, age, male sex, and renal dysfunction). These data, together with clinical trial data suggesting comparable medium-term stroke outcomes compared with SAVR, are reassuring that there is no significant long-term increase in stroke rate after TAVI.

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