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SAN FRANCISCO -- Transapical transaortic valve repair (TA-TAVR) may be inferior to standard repair for older patients who are candidates for surgery, researchers said here.

The STACCATO trial was halted early because of an excess of cardiovascular events among elderly patients having the less invasive procedure, Leif Thuesen, MD, of Aarhus University Hospital in Aarhus, Denmark, and colleagues reported at the Transcatheter Cardiovascular Therapeutics meeting.

"In its present phase of development, transapical transaortic valve repair seems inferior to surgical valve repair in older, operable patients," Thuesen said.

But a number of other clinicians at the meeting said the trial was designed to fail, citing issues with expectations regarding event rates and selection bias.

"I think it was an incredibly poorly designed study, and poorly executed, and it was set up to fail -- and fail it did," Michael Mack, MD, of Baylor Healthcare in Plano, Texas, said during a press briefing.

The role of transaortic TAVR in surgically lower-risk patients is still unclear, Thuesen said, so he and his colleagues set out to enroll 200 patients at two Danish centers to compare the transaortic procedure with regular surgery in lower-risk patients over age 70 who would otherwise be candidates for the surgical procedure.

The primary endpoint was a composite of death, stroke, and/or renal failure at 30 days. To eliminate learning curve issues, the study began only after at least 40 procedures had been done at the centers.

Thuesen said the safety concerns halted the study last May, after only 70 patients had been enrolled.

At 30 days, the primary endpoint was met in five TA-TAVR patients -- there were two deaths, two major strokes, and one case of renal failure -- compared with just one stroke in the surgical repair group.

At three months, Thuesen said, there were still more events in the TA-TAVR group -- eight events compared with two in the surgery group.

He noted that valvular leakage was especially a problem, with 13% of TA-TAVR patients having moderate-to-severe leakage and 43% having minimal leakage, versus only 6% with minimal leakage in the surgery arm (P<0.001).

He added that there have since been significant improvements in the TA-TAVR procedure: Routine preoperative multi-slice CT assessment allows for more accurate valve sizing, and the availability of a 29-mm valve has helped to minimize leakage.

Mack said he took issue with the anticipated event rate for the transapical group, which was set at 2.5% compared with 13.5% for the surgical group.

"Nowhere in the world, for a composite endpoint, are you going to have a 2.5% event rate," he said.

Thuesen countered that researchers were very optimistic about the technology at the time the trial was designed and admitted that the power calculations "were really completely wrong."

"It was an eye-opener to us," he said. "We expected one result but got the opposite."

Juan Granada, MD, of Columbia University in New York City, emphasized concerns about selection bias.

"You cherry-picked the patients, and the leftovers were the ones who were actually randomized," he said during the briefing. "I don't think this is truly a fair randomization."

Not all researchers, however, felt the study was mishandled.

"I think there's a bit of an issue here, and that this is a bit of a wake-up call that going down into STS scores of 4 to 6 at this time may be a significant issue," said Joseph Bavaria, MD, of the University of Pennsylvania. "I think this trial is more of a clearing call about the great results you get with surgical repair."

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