NOTION: TAVR Still Holds Sway in Low-Risk Patients at 6 Years

Patrice Wendling

May 29, 2018

PARIS — Follow-up data from low-risk patients through 6 years of the NOTION trial continue to favor transcatheter aortic valve replacement (TAVR) with the self-expanding CoreValve (Medtronic) over surgical bioprostheses for valve hemodynamic performance and structural deterioration.

Rates of bioprosthetic failure and endocarditis were similar for both strategies, and there was no sign of valve thrombosis in either group, Lars Søndergaard, MD, MSc, Rigshospitalet Copenhagen, Denmark, reported in a hotline session at the Congress of the European Association of Percutaneous Cardiovascular Interventions (EuroPCR) 2018.

At the recent American College of Cardiology 2018 Scientific Session, 5-year outcomes data from NOTION showed similar rates of stroke, myocardial infarction, and all-cause mortality between TAVR and surgical aortic valve replacement (SAVR).

Analysis of TAVR durability is important in light of its increasing use in patients with longer life expectancy who will survive their bioprosthetic valve, he said. There have also been troubling reports that TAVR valves may not be as durable as their surgical counterparts.

Session co-chair Alain Cribier, MD, University of Rouen, France, remarked that the results were eagerly anticipated and that "this is extremely encouraging."

The post hoc analysis examined valve durability in the all-comers NOTION trial using extended definitions of structural valve deterioration and valve failure standardized in a 2017 European consensus statement. The trial enrolled 280 patients (mean age, 79 years) with severe aortic stenosis and randomly assigned 145 patients to TAVR and 135 patients to SAVR. More than 80% of patients had a Society of Thoracic Surgeons score less than 4.

All-cause mortality through 6 years was 42.5% with TAVR and 37.7% with SAVR (P = .58).

Bioprosthetic valve dysfunction, defined as structural valve deterioration, nonstructural valve deterioration, bioprosthetic valve thrombosis, or endocarditis, trended lower with TAVR compared with SAVR (56.1% vs 66.7%; P = .07).

The individual component of structural valve deterioration, defined as having a mean gradient of at least 20 mm Hg, a change in mean gradient of at least 10 mm Hg from 3 months, or moderate/severe aortic regurgitation, was significantly less common with TAVR than with SAVR (4.3% vs 23.7%; P <  .0001).

Nonstructural valve deterioration was similar in the TAVR and SAVR groups (54% vs 57.8%; P = .52), driven by more moderate/severe prosthesis-patient mismatch at 3 months with SAVR (43.2% vs 57.8%) but more moderate/severe paravalvular leak with TAVR (21.6% vs 1.5%).

Rates of endocarditis were similar with TAVR and SAVR (5.8% vs 5.9%; P = .95), and no thrombosis occurred.

Søndergaard noted that patients were enrolled early in the TAVR era from 2009 to 2013 when aortic annulus sizing was based on echocardiography instead of CT imaging and no echocardiography core lab was used.

"I'm sure quite a few of these patients would have a larger valve prosthesis if there were treated today," he said.

After 6 years, the effective orifice area was larger for TAVR than for SAVR (1.53 cm2 vs 1.16 cm2), although mean gradient was lower (9.9 mm Hg vs 14.7 mm Hg; P <  .001 for both).

After the presentation, an audience member questioned why the rate of prosthesis-patient mismatch, although lower than in the surgical arm, was higher than expected with the CoreValve despite its excellent hemodynamics.

"I can't really explain why this is, but it's captured at 3 months" and may be related to small left ventricular outflow tract, Søndergaard replied.

The panel also asked how much of the hemodynamic difference between TAVR and SAVR is due to prosthesis mismatch or smaller valve size and whether the data can be used to support TAVR as the preferred option in smaller women, regardless of risk.

Søndergaard observed that there was no default strategy for these patients to receive transcatheter treatment outside a clinical trial when NOTION launched and that the self-expanding CoreValve prosthesis was believed to be the optimal treatment for patients with small annulus.

"But I'm sure if you look today at the opening area, TAVR for sure is a better option for a small lady who is going to have a prosthesis mismatch from day 1 after surgical aortic valve replacement," he said.

Panelist Corrado Tamburino, MD, University of Catania, Italy, asked whether the high rate of paravalvular leak after TAVR might have played a role in an uptick in mortality at 6 years in this group.

Søndergaard responded that multiple studies have shown having more than a mild paravalvular leak affects survival rates after TAVR, but "If you dive down to the NOTION trial and see if the patient who had a paravalvular leak more than mild had a better or worse outcome compared to the rest of the group, there was no difference. We couldn't see that."

Valve Failure

Rates of valve failure were low and similar for the transcatheter and surgical valves (7.5% vs 6.7%; P = .89). The outcome was defined by three components: valve-related death (5.0% vs 3.7%), valve re-intervention (2.2% vs 0.7%), or severe hemodynamic structural valve deterioration (0.7% vs 3.0%; all comparisons nonsignificant).

Session co-chair Ran Kornowski, MD, Rabin Medical Center, Petah Tikva, Israel, asked how many patients who initially had valve deterioration went on to have failure or whether they were a priori with failure vs deterioration.

Søndergaard replied that it is a very good point and worth following up on, but at the time of the analysis the consensus statement was only just published.

"I think what's very important is if you want to talk about failure, you need consensus on how to define failure or dysfunction, both for the surgical group and for the transcatheter group, and maybe even more important, you need to have something to compare against," he said. "A failure rate by itself doesn't say anything. You have to say, what was the alternative for the patient?"

NOTION was funded by the Danish Heart Foundation, and Medtronic provided statistical support. Søndergaard reported consultancy fees and institutional research grants from Abbott, Boston Scientific, Edwards Lifesciences, Medtronic, and Symetis.

Congress of the European Association of Percutaneous Cardiovascular Interventions (EuroPCR) 2018. Presented May 23, 2018.

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