EXPERT ANALYSIS FROM THE AHA SCIENTIFIC SESSIONS
NEW ORLEANS (FRONTLINE MEDICAL NEWS) – Despite increasing use of transcatheter aortic valve replacement for patients with severe aortic stenosis at intermediate risk for surgery, the procedure is meeting selected resistance because of ongoing concerns about the procedure’s limitations.
As more data emerge from randomized trials and registries, cardiologists and cardiothoracic surgeons see the choice between transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) for patients at intermediate surgical risk as something to individualize based on factors that include age, the type of TAVR access possible (transfemoral or an alternative route), and of course, patient preference. An added variable is the constant stream of new data that keeps TAVR in flux, with improved and smaller valves and delivery systems coming onto the market that eclipse the experience and lessons learned from older TAVR systems.
In intermediate-risk patients, usually defined as those with a Society of Thoracic Surgeons (STS) mortality risk score of 4%-8%, “I think you can go either way,” said Frank W. Sellke, MD , at the American Heart Association scientific sessions.
“If a patient is 90 years old and can’t expect to live more than a couple of years, you use TAVR; but if the patient is 55 years old and can expect to live 30 years, I would recommend SAVR,” said Dr. Sellke, professor and chief of cardiothoracic surgery at Brown University in Providence, R.I.
He rattled off four things about TAVR that keep it from being for everyone: periprocedural vascular complications, higher rates of paravalvular leak than with surgery, leaflet thrombosis (a phenomenon with unclear clinical consequences), and undocumented long-term durability.
Dr. Sellke made these comments while discussing the report at the meeting on registry data collected from nearly 6,000 intermediate-risk patients who underwent TAVR or SAVR in Germany during January 2011 through December 2013 and assembled in the German Aortic Valve Registry . During that 3-year period, German TAVR patients could receive either the SAPIEN XT valve or the CoreValve, two TAVR systems that now have been superseded in both Europe and the United States by next-generation systems, SAPIEN 3 and Evolut R.
Limitations of a transthoracic approach
Another factor limiting TAVR is the endovascular approach. The best TAVR results by far have come from using a transfemoral approach for endovascular valve placement, but experts estimate that today at least 10% of patients considered for TAVR have a vascular anatomy that makes the transfemoral TAVR impossible. In the past, when such patients underwent TAVR, it was via either a transapical or transaortic approach (collectively called transthoracic), although additional endovascular entry sites are now being tested.
The limitations of transthoracic TAVR were underscored by results from a prespecified quality-of-life analysis done as part of the PARTNER 2 trial that compared the SAPIEN XT system with SAVR in intermediate-risk patients ( N Engl J Med. 2016 April 27;374[17]:1609-20 ).
“The most important finding was a significant interaction of health status and TAVR access site,” said David J. Cohen , MD, in presenting the findings at the Transcatheter Cardiovascular Therapeutics annual meeting in Washington. In PARTNER 2, of the 1,011 patients who underwent TAVR, 775 (77%) had their procedure via a transfemoral approach, and 236 (23%) had it by a transthoracic approach. At 1 month after treatment, the average overall summary score on the Kansas City Cardiomyopathy Questionnaire ( KCCQ ) had increased by 14 points among the transfemoral TAVR patients, compared with the randomized SAVR patients, a short-term gain in health status by the TAVR patients over the SAVR patients that was both statistically significant and highly clinically meaningful (a 5-point increase in KCCQ score is considered clinically meaningful), reported Dr. Cohen, director of cardiovascular research and an interventional cardiologist at St. Luke’s Health System in Kansas City, Mo.
In contrast, the patients in the study who had their TAVR done by a transthoracic route had a statistically nonsignificant incremental gain in their KCCQ score, compared with randomized SAVR patients, after 1 month, and their incremental rise in KCCQ score was not clinically meaningful.
The investigators measured KCCQ scores at both 1 and 2 years after treatment, and they were similar regardless of whether patients had undergone TAVR or SAVR in both the transfemoral and transthoracic subgroups. All the quality-of-life benefit from TAVR compared with SAVR occurred only during the first month (and possibly for a few additional months beyond that) and only in TAVR patients treated by the transfemoral route. Dr. Cohen stressed that the SAVR patients in both the transfemoral and transthoracic subgroups had very similar outcomes, showing that patient differences could not explain why the transfemoral patients received a much greater incremental benefit, compared with the SAVR patients, at 1 month than did the transthoracic patients.
“A transthoracic TAVR approach may not be preferable to SAVR, at least in the short to intermediate term,” said Dr. Cohen. “There is no benefit from TAVR, compared with SAVR, if you can’t do it transfemorally, although emerging evidence has suggested that other nontransfemoral approaches that stay out of the chest may provide benefit similar to transfemoral TAVR. The message is, stay out of the chest,” he concluded.
Clinicians had already begun to appreciate the limitations of transthoracic TAVR based on prior reports, noted Craig R. Smith, MD , professor and chairman of surgery at Columbia University Medical Center in New York. “Transapical and transaortic approaches are playing increasingly small roles,” he said in an interview during the American Heart Association meeting. “A strong argument can be made for using SAVR if the patient is not a candidate for transfemoral TAVR; it’s how patients are often triaged.”
Concerns about durability
The durability of TAVR valves is another concern that has recently been influencing patients as they decide between TAVR and SAVR, said Dr. Smith. “A lot of patients don’t want TAVR because of their concerns about its durability.” These patients usually cite evidence reported in May 2016 at the annual congress of the European Association of Percutaneous Cardiovascular Interventions in Paris by Danny Dvir, MD , on longer-term follow-up of 378 patients who underwent TAVR at either of two pioneering centers. A retrospective review suggested a valve degeneration rate of about 50% after 8 years, Dr. Dvir reported.
This report “has gotten a lot of penetration over the Internet, and a lot of patients don’t like the uncertainty” about TAVR durability that this report produced. “A lot of the time now, patients come in with a fixed idea of whether they want TAVR or SAVR,” Dr. Smith said.
Dr. Smith essentially agreed with Dr. Sellke on the current role for TAVR relative to SAVR in lower-risk patients.
“If the patient is clearly intermediate risk, with an STS mortality risk of more than 6% and is at least 80 years old, then they’ll have TAVR 99% of the time. But if it’s a 75 year old with an STS score of 3.2% and otherwise healthy, the best choice is not as clear.”
Another cardiothoracic surgeon with lots of TAVR experience, Michael J. Reardon, MD , has much more enthusiasm for TAVR. “In my practice, I use TAVR exclusively in patients at least 80 years old. I don‘t care how healthy they look,” said Dr. Reardon, professor of cardiovascular surgery at Houston Methodist. He acknowledged that broader use of TAVR for intermediate-risk patients is getting push back from other cardiothoracic surgeons.
Dr. Sellke is one such surgeon, and he called uncertain TAVR valve durability the deciding factor. “We need longer-term data on [TAVR] valve longevity before we routinely put them into intermediate- or low-risk patients,” he said during a panel discussion at the meeting.
Dr. Reardon highlighted that newer TAVR systems have been reducing problems such as paravalvular leaks and the need for pacemakers following placement of self-expanding TAVR valves. Despite these technical improvements, the final frontier for TAVR for lower-risk patients is valve durability, Dr. Reardon said in an interview.
“I’m convinced the durability is there, and that any 80-year-old patient who is anatomically suited for transfemoral TAVR should get it no matter now healthy they look. If their likely survival is 15 years or less, then they are reasonable candidates for TAVR.”
Dr. Sellke had no relevant disclosures. PARTNER 2 was funded by Edwards, the company that markets Sapient TAVR systems. Dr. Cohen had no relevant disclosures. Dr. Smith has been an investigator in the PARTNER studies. Dr. Reardon has been a consultant to Medtronic, the company that markets the CoreValve and Evolut R TAVR systems.
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