Deborah Brauser

March 19, 2015

SAN DIEGO, CA — Although past studies, including long-term results presented this week from the PARTNER cohort A trial, have shown that transcatheter aortic-valve replacement (TAVR) is an effective alternative to surgical aortic-valve replacement (SAVR) for patients with severe aortic-valve stenosis who are at high risk for surgery, results from the Nordic Aortic Valve Intervention Trial (NOTION) suggest that it may be a viable option for low-risk patients, too[1].

NOTION enrolled almost 300 patients older than 70 years with severe aortic-valve stenosis but deemed low risk for surgery at three European centers. One-year results showed no significant differences in the composite rate of death from any cause, stroke, or MI (the primary outcome) between those undergoing TAVR and those undergoing SAVR.

While the TAVR group had more conduction abnormalities and greater total aortic-valve regurgitation, the SAVR group had more episodes of major bleeding, cardiogenic shock, and new-onset or worsening AF.

These findings were presented at a featured clinical-research session here at the American College of Cardiology (ACC) 2015 Scientific Sessions and simultaneously published in the Journal of the American College of Cardiology.

"The NOTION trial was the first all-comers trials to randomize low-risk patients to TAVR or SAVR," lead author Dr Hans Gustav Hørsted Thyregod (Heart Center, Rigshospitalet, Copenhagen University Hospital, Denmark) told meeting attendees, adding that long-term durability and morbidity data in this patient population are now needed.

Dr David E Kandzari (Piedmont Heart Institute, Atlanta, GA) told heartwire from Medscape afterward that this was a "very provocative study."

"I believe in many ways a 'tie' is a win in this instance. And numerically, at least, all the individual end points of the composite were lower with [TAVR]," said Kandzari, who was not involved with the research.

"This is offset by higher regurgitation and higher-than-previously-reported frequency of pacemaker implantation. But I think there is some further opportunity to study whether that event rate remains as high with newer generations of that specific catheter and in newer generations of different transcatheter technologies," he added.

Similar Outcomes

A total of 280 older patients (mean age 79.1 years) with degenerative aortic-valve stenosis were enrolled between December 2009 and April 2013 at one of two centers in Denmark or at one center in Sweden; 81.8% of the participants scored <4 on the STS predicted risk of mortality.

All patients were randomized to the self-expanding CoreValve (Medtronic)  bioprosthesis (n=145, 53.8% men) or to SAVR (n=135, 52.6% men). The primary outcome was assessed 1 year later, with follow-ups scheduled for up to 5 years.

Exploratory outcomes included cardiovascular death, cardiogenic shock, prosthesis reintervention, AF, and "conduction abnormalities requiring permanent pacemaker." Renal and bleeding complications were also recorded, as was total aortic-valve regurgitation.

Intention-to-treat results showed that the composite rate of death from any cause, stroke, or MI was 13.1% in the TAVR group vs 16.3% in the SAVR group, which was not statistically different. The difference was still not significant in the as-treated population (11.3% vs 15.7%, respectively).

There were also no between-group differences in cardiovascular death, transient ischemic attack, major vascular complications, or prosthesis reintervention.

When examining safety outcomes, the researchers found that the patients had "different spectra of complications related to the different nature of the treatments."

The TAVR group had significantly lower rates of major or life-threatening bleeding vs the SAVR group (11.3% vs 20.9%, respectively; P=0.03), as well as acute kidney injury (0.7% vs 6.7%; P=0.01), and cardiogenic shock (4.2% vs 10.4%; P=0.05).

They also spent less mean time in the hospital postprocedure (mean days 8.9 vs 12.9; P=0.001) and had lower rates of AF first presenting or worsening at 30 days (16.9% vs 57.8%; P<0.001) and during the first year (21.2% vs 59.4%; P<0.001).

However, patients undergoing TAVR had significantly higher rates of pacemaker implantation vs the SAVR-treated group (38% vs 2.4%, respectively; P<0.001), as well as more mild dyspnea at 1 year (29.5% vs 15%; P=0.01) and higher rates of relevant total aortic-valve regurgitation at 3 months to 1 year (moderate to severe at 1 year, 15.7% vs 0.9%; P<0.001).

"Therefore, at present we are not able to recommend or refute one procedure over the other in lower-risk patients," write the investigators, adding that more research looking into these issues is definitely needed.

A Leap Forward

When asked for comment, Kandzari noted that the study had a "modest" number of participants and was conducted at a modest number of institutions but was ambitious in its objectives.

"It was statistically underpowered for these important end points. Nevertheless, the study really highlighted the potential procedural safety and benefit of [TAVR]—and extended it to a very low-risk population that has not really been formerly studied," especially in comparison with SAVR, said Kandzari.

"The real issue raised by this study is the need for longitudinal follow-up for longevity. It isn't practice changing, but I think this study is more than just a step: it's a real leap. It opens the door for larger trials that truly would extend this potential to this type of low-risk and even intermediate-risk population," he concluded.

Funding was provided by the Danish Heart Foundation. Thyregod reports no relevant financial relationships. Disclosures for the coauthors are listed in the article. Kandzari reports receiving research, grants, and consulting honoraria from Medtronic, "but none from transcatheter-valve therapy."

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