STACCATO: Transapical TAVR Inferior to Surgery for Operable Elderly Patients

SAN FRANCISCO, CALIF.—Data from the randomized STACCATO trial showed that among elderly operable patients, transcatheter aortic valve replacement (TAVR) via the transapical route resulted in more early adverse events than surgical AVR. However, the trial, presented by Leif Thuesen, MD, of Aarhus University Hospital in Aarhus, Denmark, was stopped prematurely, and even its initiation was questioned by some commentators.

The study focused on patients with valvular aortic stenosis who were aged at least 70 years (later amended to 75 years), were deemed operable, and had an expected survival of more than 1 year following successful treatment.  Researchers planned to enroll 200 patients, but after randomization of 70 patients to TAVR (n=34) or surgery (n=36), the study was terminated on the advice of the Data Safety Monitoring Board due to an excess number of adverse events in the TAVR arm.

The two groups were well balanced for baseline characteristics. On average patients were slightly over 80 years old. The STS score ranged from 3.1±1.5 for surgery patients to 3.4±1.2 for TAVR patients.

The primary endpoint (the composite of all-cause mortality, major stroke and renal failure  at 30 days) was met in five TAVR patients, comprising two deaths, two major strokes and one case of renal failure, compared with one stroke in the surgery group (P=.07).

Aortic valve area and peak aortic gradient were significantly improved compared with baseline by both treatments (P<.0001), but afterwards there was no difference between the TAVR and surgery groups for these parameters.

After 30 days, 13% of TAVR patients had moderate/severe paravalvular leakage, 43% had minimal leakage and 43% had no leakage, whereas in the surgical group only 6% experienced minimal leakage and 94% had none (P<.001). NYHA functional class improved from baseline to 3 months in both groups, but at that point there was no significant difference  between the treatment groups in the distribution of NYHA class (P=.16). In addition, no differences were seen with regard to MI, placement of a permanent pacemaker, hospital stay, or composite physical or mental function scores.

Dr. Thuesen acknowledged several limitations of the study, including the fact that only one third of the anticipated number of patients were included. Therefore, the excess number of adverse events in the TAVR group might have been due to the play of chance. Thuesen also noted that preoperative multislice CT assessment, which was not used in the trial, might have optimized valve sizing.

Is transapical at fault—or the trial?

In comments following the presentation, A. Pieter Kappetein, MD, PhD, of Thoraxcenter, Rotterdam, the Netherlands, pointed out that many of the complications seen in TAVR patients were not necessarily due to use of the transapical route. Paravalvular leakage and stroke, for example, are also seen in the transfemoral approach. Also, he said, the anticipated primary endpoint rate of 13.5% for surgery was probably pessimistic, while the expectation of a 2.5% rate for TAVR was optimistic.

Perhaps the most important issue, however, is whether the centers had sufficient transapical experience to embark on the trial, Dr. Kappetein said, adding, “I think this trial deserves a new trial with experienced centers, showing better inclusion and exclusion criteria, and perhaps a little bit higher risk patients, to see if transapical TAVR is as bad as had been shown here — which I doubt.”

TCT Course Director Martin B. Leon, MD, of Columbia University Medical Center in New York, was more blunt. “The STACCATO trial should never have been done,” he said. “With a mean STS of 3, we’re talking about many patients who had an STS score of 1 or 2. There was just not enough experience with transapical [TAVR] to randomize that patient cohort with confidence and to think you could achieve comparable results.

“I just don’t know why there were so many events in this small cohort,” he added. “Maybe it was sample size, maybe it was early experiences. Presently we would not have expected this degree of adverse events with a transapical procedure in experienced centers.”

Disclosures
  • Dr. Kappetein reports no relevant conflicts of interest.
  • Dr. Leon reports receiving grant support/research fees, consultant fees and honoraria from multiple pharmaceutical and device corporations.
  • Dr. Thuesen reports serving as a physician proctor for Edwards Lifesciences.

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