AT EUROPCR 2016
PARIS (FRONTLINE MEDICAL NEWS) – The first-ever study of the long-term durability of transcatheter bioprosthetic aortic valves has documented a disturbing rise in the valve degeneration rate occurring 5-7 years post implant.
Prior consistently reassuring follow-up studies have been intermediate in length, with a maximum of 5 years. The PARTNER 2A trial, which generated enormous enthusiasm for moving TAVR to intermediate-risk patients on the basis of positive results presented at the 2016 meeting of the American College of Cardiology, reported 2-year results.
“We found, as have others, that there’s very little degeneration in the first 4 years: 94% freedom from degeneration. But at 6 years, it’s 82%, and we estimate that by 8 years, it’s about 50%,” Dr. Danny Dvir reported at the annual congress of the European Association of Percutaneous Cardiovascular Interventions.
“We need to be cautious: This is our first look at the data. But we have a signal for a problem,” said Dr. Dvir of St. Paul’s Hospital in Vancouver.
He presented a retrospective study of 378 patients who underwent TAVR 5-14 years ago at two pioneering centers for the procedure: St. Paul’s and Charles Nicolle Hospital in Rouen, France. Patients’ average age at the time of TAVR was 82.3 years, with an STS score of 8.3%. The study featured serial echocardiography conducted during house calls in this frail elderly population.
Thirty-five patients developed prosthetic valve degeneration, defined by at least moderate regurgitation and/or a mean gradient of at least 20 mm Hg in 23 cases and stenosis in 12. The risk of degeneration was unrelated to the use of warfarin, a finding that suggests the valve deterioration issue is unrelated to clotting. The strongest risk factor for transcatheter valve degeneration in this study was baseline renal failure at the time of TAVR.
Dr. Dvir’s presentation was the talk of the meeting, and it cast a pall over the proceedings. The red flag raised by the study regarding valve durability has major implications regarding the current enthusiasm among many interventional cardiologists to routinely extend TAVR to intermediate and even lower-risk patients. As one audience member later confessed, “I have felt sick since hearing that presentation.”
Discussant Dr. A. Pieter Kappetein observed that transcatheter heart valve durability was a hot topic of discussion about 4 years ago but subsequently faded below the radar as a concern – until Dr. Dvir’s study.
“This is a very important study that puts transcatheter heart valve implantation in a little bit different light,” said Dr. Kappetein, professor of cardiothoracic surgery at Erasmus University in Rotterdam, the Netherlands.
He noted that the surgical aortic valve replacement (SAVR) literature shows that the rate of structural valve deterioration is age related. It’s higher in 75-year-olds than in 85-year-olds, and higher still in 65-year-olds.
“Valve degeneration didn’t play a major role when we were doing TAVR in 80- and 85-year-olds because of their limited life expectancy, but it will play a role in younger patients. So I think we have to be careful before we move toward lower-risk patients,” the surgeon continued.
Dr. Jean-Francois Obadia , who performs both SAVR and TAVR, noted that the median duration of freedom from valve degeneration for Edwards Lifescience’s Carpentier surgical aortic valve is a hefty 17.9 years.
“This should be the gold standard,” declared Dr. Obadia, head of the department of adult cardiovascular surgery and heart transplantation at the Louis Pradel Cardiothoracic Hospital of Claude Bernard University in Lyon, France.
“Dr. Dvir’s study is one of the key messages we all should take back home: a 50% rate of valve deterioration at 8 years. Valve deterioration is the Achilles’ heel of bioprostheses. There is a lot of improvement left to do for the TAVR,” he said.
Dr. Dvir and others were quick to note that his long-term study was of necessity restricted to early-generation, balloon-expandable devices: the Cribier Edwards , Edwards Sapien , and Sapien XT valves. Contemporary valves, patient selection methods, and procedural techniques are far advanced in comparison.
“The Sapien 3 has much less paravalvular leakage than earlier-generation valves. Maybe with less paravalvular leakage and better hemodynamics there will be a decreased rate of degeneration. It could be. We need to see. We have to wait a few more years to see if later-generation transcatheter heart valves are more durable,” Dr. Dvir said.
To gain a better understanding of the full dimensions of the valve degeneration issue, he and his coinvestigators have formed the VALID (VAlve Long-term Durability International Data) registry. Operators interested in contributing patients to what is hoped will be a very large and informative data base are encouraged to contact Dr. Dvir ( ddvir@providencehealth.bc.ca ).
In the meantime, he has reservations about extending TAVR to intermediate-risk patients outside of the rigorous clinical trial setting. He added that he’d feel far more comfortable in performing TAVR in intermediate-risk 70- to 75-year-olds if there was a tried and true valve-in-valve replacement method, something that doesn’t yet exist. The major limitation of current attempts at valve-in-valve replacement is underexpansion because the former valve doesn’t allow sufficient room for the new one to expand fully, resulting in residual stenosis.
“If you tell me that you can implant a platform that will enable a safe valve-in-valve procedure in 5, 7, 10 years – a less invasive bailout for a failed prosthetic valve – if you can do that safely and effectively I would be more keen to do TAVR even in a young patient,” the interventional cardiologist said.
He and others are working on this unmet need. Dr. Dvir’s novel valve, being developed with Edwards Lifesciences, has performed well in valve-in-valve procedures in cadavers and animals. The first clinical trials are being planned.
“We need to think always that a bioprosthetic valve is not a cure, it’s a palliation. We treat the patients, they feel better, but we leave them with some kind of a chronic disease that’s prone to thrombosis, prone to degeneration and failure, prone to many different things,” he reflected.
The study was conducted without commercial support. Dr. Dvir reported serving as a consultant to Edwards Lifesciences, Medtronic, and St. Jude Medical.
