UK TAVI: Similar Outcomes to Surgery in Real World

Sue Hughes  

March 29, 2020

Transcatheter aortic valve replacement (TAVR) was not inferior to conventional surgery with respect to death from any cause at 1 year in a new real-world study in patients age 70 years or older with severe symptomatic aortic stenosis at increased operative risk due to age or comorbidity.

The UK TAVI study was presented March 29 at the "virtual" American College of Cardiology 2020 Scientific Session (ACC.20)/World Congress of Cardiology (WCC).

The trial involved a broad group of patients who were treated at every medical center that performs the transcatheter procedure across the United Kingdom.

"The importance of this trial is that it confirms the effectiveness of the TAVR strategy in a real-world setting," said lead author, William D. Toff, MD, professor of cardiology at the University of Leicester, United Kingdom.

Previous clinical trials have found TAVR to be noninferior or superior to open-heart surgery for various patient groups, but most trials have been limited to medical centers that perform a high volume of procedures or focus on the use of specific types of replacement valves, he noted.

"Our results are concordant with those from earlier trials in intermediate- and low-risk patients, but those earlier trials were performed in the best centers and had many exclusion criteria. We have replicated those results in populations more representative of the real world."

"I think it is a very important message that supports the findings in earlier trials that were focused on showing whether TAVR can work under ideal conditions, while our trial shows that it does work in real-world clinical practice," he added.

The UK TAVI trial enrolled 913 patients referred for treatment of severe aortic stenosis at 34 UK sites from 2014 to 2018. They were randomly assigned to receive TAVR or open-heart surgery.

Enrollment was limited to participants age 70 years or older (with additional risk factors) or age 80 years or older (with or without additional risk factors). The average age was 81 years.

Overall, participants were at intermediate to low risk from surgery, with a median Society of Thoracic Surgeons (STS) risk score of 2.6%. However, researchers did not specify a particular risk score cutoff for enrollment.

"This allowed the trial to evolve along with changes in guidelines and practice regarding TAVR over the course of the study and to reflect physicians' nuanced, real-world approach to considering risk in decision-making rather than taking a formulaic approach," Toff said.

At 1 year, the rate of death from any cause (the primary endpoint) was 4.6% in the TAVR group and 6.6% in the surgery group, a difference that met the trial's prespecified threshold for noninferiority of TAVR.

Rates of death from cardiovascular disease or stroke were also similar between the two groups.

Patients who received TAVR had a significantly higher rate of vascular complications (4.8%) than those receiving surgery (1.3%).

TAVR patients were also more likely to have a pacemaker implanted. This occurred in 12.2% of TAVR patients and 6.6% of those undergoing surgery.

In addition, patients who underwent TAVR had a higher rate of aortic regurgitation. Mild aortic regurgitation occurred at 1 year in 38.3% of the TAVR group and 11.7% of the surgery group, whereas moderate regurgitation occurred in 2.3% of TAVR patients and 0.6% of surgery patients.

On the other hand, patients undergoing TAVR had a significantly lower rate of major bleeding complications, which occurred in 6.3% of patients having TAVR and 17.1% of those undergoing surgery.

TAVR was also associated with a shorter hospital stay, fewer days in intensive care, and a faster improvement in functional capacity and quality of life. Functional capacity and quality-of-life measures at 6 weeks after the procedure were better in the TAVR group but by 1 year they were similar in the two groups.

"Longer follow-up is required to confirm sustained clinical benefit and valve durability to inform clinical practice, particularly in younger patients," Toff concluded.

"The results from our trial and others are encouraging, but patients need to be fully informed and know that the long-term durability of the TAVR valves and the long-term implications of the increased risk of aortic regurgitation are still uncertain," he added.

The researchers plan to continue to track outcomes for a minimum of 5 years.

Discussant of the UK TAVI trial at an ACC press conference, Julia Grapsa, MD, Guys and St Thomas NHS Trust, London, United Kingdom, said it was a well-designed study.

"It was impressive to see so many UK sites and the age range of patients from 70 to 91 years, and the shorter hospital stays and functional recoveries as well as reduced major bleeding in the TAVR group," Grapsa said.

"But something that was very striking to me was the increase in moderate aortic regurgitation in the TAVR arm, 2.3% versus 0.6% in the surgical arm, so it is very important to keep following these patients long term," she added.

In answer to a question during the main session about using age alone as an inclusion criterion in those over 80 years old, Toff said, "We were more comfortable taking all comers over 80 years of age because of the uncertainty about TAVR is more in relation to its durability and the clinical significance of the aortic regurgitation, which may have consequences in the longer term. But the longer term for the over 80s is obviously less of a problem than for those in their 70s."

This study was funded by the UK National Institute for Health Research Health Technology Assessment Programme. Toff reports no disclosures.

American College of Cardiology 2020 Scientific Session (ACC.20)/World Congress of Cardiology (WCC). Abstract 20-LB-20309-ACC.  Presented March 29, 2020.

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