TAVI expansion controversy continues

Reed Miller

August 09, 2012

Chicago, IL - Many physicians and patients may need to temper their enthusiasm for transcatheter aortic-valve implantation (TAVI) and take a more clear-eyed view of the risks and benefits of this alternative to valve surgery, the latest major journal editorial on TAVI argues[1].

"Clinicians must emphasize the proven short-term and long-term benefits of surgical aortic-valve replacement in patients with low surgical risk," write Drs Chintan Desai and Robert Bonow (Northwestern University, Chicago, IL). "As with all new technologies, it is essential that patient and physician expectations must be balanced with a realistic assessment of potential benefits, risks, and outcomes to provide the optimal therapy for severe aortic stenosis."

Questions about the expansion of TAVI to patients who could undergo surgery, but with high risks—as opposed to those deemed inoperable—has been a topic of debate among interventionalists and surgeons since the PARTNER results showed similar one-year mortality for TAVI and high-risk surgery patients but showed that mortality was significantly lower with TAVI than standard medical therapy in inoperable patients (30.7% vs 50.7%, p<0.001).

However, as some critics have stressed, PARTNER showed worse rates of stroke and vascular complications in TAVI patients. Also, in PARTNER, TAVI patients treated with the transapical approach because the transfemoral route was not feasible had worse outcomes than the surgery patients.

The authors observe that the stroke risk has been apparent since the early trials of transcatheter aortic-valve technology, but now paravalvular regurgitation has also become a concern. For example, in the FRANCE 2 registry, 30-day incidence of grade 2 or higher paravalvular aortic regurgitation was 17.1%. PARTNER showed that even mild paravalvular regurgitation was linked to a twofold increase in mortality risk, Desai and Bonow point out.

"These complications of [transcatheter aortic-valve replacement] TAVR provide the opportunity for further investigation and device development to improve clinical outcomes, [but] they also provide reason for pause in the rush to expand the patient population eligible for TAVR," Desai and Bonow argue. "Not only are complication rates likely to be higher in clinical practice compared with trials, the magnitude of benefit observed in many trials is often attenuated in practice."

They are especially concerned about the possibility of "indication creep" in Europe, citing data from a German registry showing that patient preference steered the treatment decision to TAVI in 13% of patients, all of whom were operable[2], and results from a Dutch cohort in which 67% of patients underwent TAVI for off-label indications[3].

More data from the German registry, showing whether or not the expansion of TAVI is decelerating, will be presented at the upcoming European Society of Cardiology conference in Munich.

Difficult conversations

Desai and Bonow stress that one of the important achievements of PARTNER is that it demonstrated the value of insisting that every aortic-valve repair or replacement candidate be evaluated by a heart team including surgeons and cardiologists. They emphasize the importance of the heart-team approach to ensuring the best possible care for the patient. "Faced with the need for valve replacement, patients and their families understandably will prefer a percutaneous treatment approach, if available, rather than open heart surgery. It is essential for clinicians to temper increasing consumer expectations for TAVR with a frank discussion emphasizing that the time has not yet come for TAVR in patients who fulfill criteria for aortic-valve replacement and have low surgical risk."

However, the editorialists are not optimistic that this discussion is happening as often as it should "The results of this trial likely represent the best outcomes that can be achieved by such a team-based approach. This multidisciplinary collaboration may not occur in all real-world practices, where individual physician and patient preference may play an overly influential role in determining treatment recommendations."

Surgeon Dr Michael Mack (Baylor Health Care System, Plano, TX), a PARTNER investigator, told heartwire ,"That conversation happens all the time, and it's an extremely difficult conversation [with the patient]."

Mack says that he informs patients that the TAVI approach is less invasive, but the durability of the valve is uncertain and the stroke rate is twice as high as with surgery. "Many patients say 'I understand all of that. I just don't want surgery.' And this is me, as a surgeon, explaining to them. Very often you're faced with the option of telling them 'Sorry, I can't get you [TAVI], it's either surgery or nothing.' And many patients say 'I'll take nothing.' That's how much patients don't want surgery. So you can see how clinicians faced with patients saying that will say, 'Okay, we'll cheat a little bit and put a transcatheter valve in,' " Mack said.

Is TAVI expanding too fast in Europe?

As reported by heart wire , the tendency for patients to drive the TAVI-vs-surgery decision process is one of many raised by Dr Hans Van Brabandt (Belgian Health Care Knowledge Center, Brussels) and colleagues in a recent editorial in BMJ . The authors of that editorial conducted a cost-effectiveness analysis showing that TAVI can be justifiable only for inoperable patients—about 10% of the aortic-valve-disease population—and is not a safe or cost-effective alternative to surgery for patients who could undergo surgical valve replacement.

Just because it's off-label doesn't mean it's the wrong thing to do or that it's just interventionalists going crazy.

"In the high-risk patients, if you take into account the economic aspects, then it's not rational at all to reimburse, for the reason that it's more expensive for not a better result," coauthor Mattias Neyt (Belgian Health Care Knowledge Center, Brussels) told heart wire . The Belgian group argues that TAVI devices are among many devices that were allowed onto the European market without sufficient evidence of their effectiveness because the CE Mark rules are too weak. "A general problem is our [device regulation] legislation, and we can only hope that this legislation will become stricter in the future and ask for more evidence on new devices. We want to be surer that what we use is better for the patients in mortality, morbidity, or quality of life. This evidence is often lacking for devices on the European market."

Mack said, "I'm sure there's abuse that goes on and has gone on, which is why there is such a push-back, with everything from carotid stenting to [implantable cardioverter defibrillators] ICDs to TAVI right now. Clearly that abuse has led to this scrutiny. But just because it's off-label doesn't mean it's the wrong thing to do or that it's just interventionalists going crazy.

"You're trying so hard to do the right thing, but sometimes when you're faced with the patient in front of you, that's the only patient you've got," Mack said. "People are so focused on the short term and immediate outcome that they'd rather buy into [a less invasive option] even if there's a greater long-term benefit from a more invasive alternative."

Mack said he expects expansion of TAVI beyond inoperable patients to move more slowly in the US than it has in Europe because the Centers for Medicare and Medicaid Services [CMS] is likely to be "pretty restrictive in what they reimburse for in the United States. The reimbursement is going to be closely aligned with FDA labeling, and the effect of that will be to attenuate the degree of expansion, unlike what is happening in Germany," he said. The CMS recently announced coverage for TAVI for FDA-approved indications but restricted coverage to experienced operators and insists that TAVI data be collected in a national registry. The FDA's advisors recently recommended approving TAVI for high-risk operable patients.

Two-year results of the PARTNER II trial, which is comparing TAVI and surgery in "intermediate-risk" patients, will not be available until sometime in 2015, he predicted.

Bonow has previously received consultancy fees from Edwards Lifesciences . Desai reported no disclosures. Mack has a nonremunerative position of interest on the executive committee of the PARTNER trial for Edwards Lifesciences. The authors of the Belgian study declare no conflicts of interest.




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