Percutaneous Aortic Valve Replacement: Early Promise
Fifty-one patients successfully received femoral AVR for severe aortic stenosis.
Past research has confirmed that transcatheter aortic valve replacement (AVR) therapy is effective in either balloon-expandable or self-expanding delivery systems. The short-term hemodynamic results have also been consistently excellent, according to Martin B. Leon, MD, founder of the Cardiovascular Research Foundation and Professor of Medicine at Columbia University Medical Center. However, the route of approach, either antegrade or retrograde, has complicated the procedure.
Summarizing several pending studies in a plenary session yesterday, Leon discussed the future of AVR for patients with severe aortic stenosis. He called for randomized clinical trials in patients with aortic stenosis at high surgical risk, advising that such trials should compare transcatheter AVR systems with appropriate control therapies.
Unmet need
“Patients with severe aortic stenosis benefit tremendously from AVR,” Leon said. “They live longer, feel better and there is a marked symptom benefit with improved left ventricular (LV) function (Figure), particularly if they had antecedent LV dysfunction.”
But not all patients with aoritc stenosis receive AVR. Data from 92 hospitals in 25 countries, where 5,001 patients were treated from April 2001 to July 2001, indicated that 31.8% of patients with severe valvular heart disease did not receive intervention, despite having NYHA Class III/IV symptoms, Leon said.
In data from a new echocardiography study from the University of Michigan Heart and Vascular Center by David Bach, MD, 47% of 145 patients with severe aortic stenosis did not receive AVR and were treated medically. At 206-day follow-up, 16 of those patients (17%) had died.
New data
In a study conducted by John G. Webb, MD, Director of Interventional Cardiology at St. Paul’s Hospital in Vancouver, British Columbia, 80 patients received AVR (58 femoral and 22 apical). Webb and colleagues, who will present their full data on Thursday, successfully performed transcatheter AVR via a femoral approach in 51 of 54 patients and with an apical approach in 18 of 22 patients.
In the group of patients with femorally placed valves, there was a 12.1% 30-day mortality rate and a 3.4% 30-day stroke rate.
Leon also discussed preliminary results from another transfemoral delivery trial, REVIVAL II, which will be presented today by Susheel K. Kodali, MD, of the New York-Presbyterian Hospital and Columbia University Medical Center.
Leon said that Kodali and colleagues found that retrograde delivery was successful in 47 of 54 patients. The intent-to-treat analysis of all 54 patients showed a 7.4% 30-day mortality (four deaths) and a 16.7% 30-day major adverse coronary events rate (nine events).
Twenty percent of the patients were over 90 years old, said Leon, the study’s senior researcher.
The technology
The standard transcatheter AVR consists of the valve, a platform and the delivery system. The general features include a circular platform with a biologic trileaflet valve with good hemodynamic performance that minimizes flow into the coronary arteries, Leon said.
The valve does not cause significant paravalvular leaks and has a landing zone in the annular or subannular region. Sometimes hemodynamic support is necessary, and the patient must be adequately stabilized for successful implantation, he said.
The most validated system is the Cribier-Edwards Aortic Bioprosthesis, which uses a balloon-expandable stainless steel device that is made of an equine pericardial valve and is delivered via an unsheathed catheter (FlexCath). It can be delivered via antegrade, retrograde or transapical approaches.
Another device, the CoreValve Revalving System, uses a self-expanding nitinol cage bioprosthesis made of a porcine pericardial valve. It is delivered via a sheathed 21 Fr to 18 Fr catheter in a retrograde approach. The system has been studied in fewer than 100 patients, but data are promising Leon said.