LOS ANGELES – A new investigational transcatheter aortic valve implantation system, the Engager system, yields generally good early results when used to treat severe aortic valve stenosis, according to an interim analysis of a pivotal European regulatory trial.
Among the first 61 patients who underwent implantation of the valve, which is performed transapically, the 30-day rate of all-cause mortality according to intention to treat (the trial’s primary end point) was about 10%, lead investigator Dr. David M. Holzhey reported at the annual meeting of the Society of Thoracic Surgeons.
Valve implantation reduced the mean aortic gradient, which translated to an improvement in New York Heart Association functional class in nearly all cases.
Most complications were uncommon, but one-third of patients needed new pacemakers after their procedure.
"The system works as expected. It reduces the gradient and it improved the clinical outcome in these patients with severe symptomatic aortic stenosis who were at high risk for surgical aortic valve replacement," commented Dr. Holzhey, a cardiac surgeon with Heart Center Leipzig (Germany).
"We had no positioning-related complications as we have seen with other valves before. The low incidence of paravalvular leak seems to prove the concept and the design of the Engager valve," he added.
Part of the reason for the reduced leakage with the Engager is its size, Dr. Holzhey said. "The current systems are 24-French or 26-French. The 29-French [with Engager] means it is 1 mm more. In the transapical setting, this has no impact at all because the tissue spreads easily, and it’s easy to close it again. So this is one of the advantages actually of the transapical access as compared to transfemoral, for instance, that you can have larger delivery systems without any more problems," Dr. Holzhey replied.
The unusually high pacemaker rate may be attributable to other design features. "The valve ... was meant to overcome some of the drawbacks of former devices and was designed for easy, intuitive implantation, also for sealing of the leaks. This is why the valve is maybe protruding a little more into the outflow track than other systems. This might be a cause for the higher pacemaker rate," Dr. Holzhey proposed. "So the major concern with the development and design of the valve was sealing off paravalvular leakages, which seems to work, maybe at the cost of a higher pacemaker rate."
In addition, the study centers were liberal in implanting pacemakers as soon as the first postoperative day because the patients were predominantly elderly and early postoperative mobilization was the first priority, he continued.
Session attendee Dr. Craig Miller of Stanford (Calif.) University also remarked on this complication, saying, "I am alarmed by that 32% pacemaker rate at 6 months. ... We have got to figure out what is causing that and fix that. ... What do you know ... about the patients that may have predisposed them to have this extraordinarily high need for pacemakers or perceived need?"
About half of the patients had true third-degree AV block, according to Dr. Holzhey. The other half had mixed indications, such as sinus bradycardia or sick sinus syndrome. "I cannot tell you at present what the exact indications were for each single patient, but this is being investigated."
Session attendee Dr. Lars Svensson of the Cleveland Clinic noted that the original Engager system was associated with vascular injury in some cases. "Any thoughts why they made the cuff so big and so far down into the ventricle?" he asked.
"The intention was to produce a valve that facilitates implantation, makes it easy, and maybe implanter-independent, with those arms that you just sort of pull back" to deploy the valve, Dr. Holzhey replied. "The first concern was that these arms might cause hematoma or even dissection. We haven’t seen that at all." The valve’s size and height again relate to better leak prevention, he said.
A total of 125 patients from Germany, Switzerland, Belgium, and Israel were enrolled in the trial, which is the pivotal trial for device CE marking in Europe. The interim analysis was based on the first 61 patients.
They were 82 years old, on average, and 62% were women. Most had a NYHA functional class of III or IV. One-third had atrial fibrillation or flutter.
The overall rate of device success, according to Valve Academic Research Consortium (VARC) criteria, was 94%, Dr. Holzhey reported.
None of the patients experienced annulus rupture, valve embolization, conversion to open aortic valve replacement, or coronary compromise or needed to undergo a second valve implantation.