November 10, 2011 (San Francisco, California)— A study comparing the transapical approach for transcatheter aortic-valve implantation (TAVI) against conventional aortic-valve replacement surgery was stopped early due to an increase in adverse events, including an increased risk of major stroke and severe paravalvular leakage, in elderly patients eligible for surgery.

Dr Leif Thuesen

Dr Leif Thuesen (Aarhus University Hospital, Denmark), who presented the results of the STACCATO trial today at TCT 2011, said he is concerned about extending the indication of transapical TAVI to include patients who are candidates for surgery, especially given the increased risk of major stroke observed in this trial.

Dr Michael Mack

"There is no doubt there are patients who can't be operated on, and they should be treated with TAVI," Thuesen told heartwire . "But the patient who can be operated on--here, we should be very, very cautious. It's the operable patients, the low-risk patients; they should not have the TAVI procedures, but that's what is happening. We had one patient, for instance, who did not want the conventional operation, so he had the TAVI procedure in Canada. That's how it is. Indications are slipping."

The results of the study were presented during the late-breaking clinical-trials session, as well as during a morning press conference. After Thuesen's presentation to the media, Dr Michael Mack (University of Texas, Dallas) pulled no punches in his criticism of the trial, saying the study was poorly designed and poorly executed. Mack said the trial was designed too optimistically and powered for event rates in the TAVI arm that were too low. Moreover, some of the events that stopped the trial, including one patient in the transapical-TAVI arm who died while on the waiting list for the procedure, skewed the results.

"I think there is some misinformation here, based on invalid trial design, that is likely to hurt the field," Mack told heartwire .


The STACCATO trial was designed three years ago and included elderly patients with valvular aortic stenosis who could be treated with surgery or transapical TAVI. Based on data from a surgery registry, they anticipated a surgical-event rate--defined as a composite of 30-day all-cause mortality, major stroke, and/or renal failure--of 13.5% and an estimated event rate in the TAVI arm of 2.5%. The study was stopped due to an increase in adverse events in the TAVI arm after the inclusion of 70 patients.

Indications are slipping.

Regarding the primary end point in the transapical-TAVI arm, there was one non–treatment-related death, one left coronary artery blockage, two major strokes, and one patient who had renal failure requiring dialysis. In the surgical arm, there was one case of perioperative major stroke. Other adverse events in the TAVI arm included a transient ischemic attack followed later with a major stroke, two perioperative cases of severe paravalvular leakage, one perioperative aortic rupture, one left main occlusion during balloon valvuloplasty, and one case of major bleeding.

Thuesen emphasized that the study was initiated three years ago and that the transapical TAVI devices at that time were relatively "unsophisticated" and not available in the full range of sizes now on the market. Moreover, he noted that the study investigators were optimistic about the success of TAVI in this population, especially given their absence of clinical events before the study was started, and for that reason they assumed an event rate of 2.5%, which he admitted was "completely wrong." He noted that the trial began after investigators had performed approximately 40 transapical TAVI procedures.

Dr Joseph Bavaria

To heartwire , however, Mack said the event rates were too low and that investigators should have estimated an event rate closer to 13%, similar to the event rate assumed in the surgical arm. Dr Joseph Bavaria (University of Pennsylvania, Philadelphia), on the other hand, saw a silver lining in the data, especially for surgeons. He said that the study shows the great surgical results obtained in patients with an average Society of Thoracic Surgeons (STS) risk score of 3.4.

Discussing the results and the stopping of the trial, Thuesen said that operators are now much better at handling paravalvular leakage, and newer devices might provide a much better fit into the aorta. Moreover, multislice computed tomography (MSCT) is able to provide better preoperative assessments over echocardiography, which was used in STACCATO. Still, despite the limitations of the trial, Thuesen said that in the current phase of development, transapical TAVI is likely inferior to surgery.

Asked about patients who want TAVI despite eligibility for surgery, Thuesen told heartwire that "we should try to persuade them to have surgery, no doubt." Mack, on the other hand, said that on the front lines surgeons are forced to tell patients that their surgical risks are too low for TAVI and that surgery is the recommended treatment. "The patients don't want what I'm selling," said Mack.


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