麻豆传媒

The prospect of bringing transcatheter aortic valve replacement (TAVR) to lower-risk populations has interventional cardiologists and cardiothoracic surgeons disputing how far to push the limits of the procedure.

Few data have given an edge to TAVR over surgery, but regulators in Europe and the U.S. have started to green-light the procedure in patients beyond the most high-risk.

Two commentaries in JACC: Cardiovascular Interventions argued the opposing viewpoints.

Interventionalist Supports Expansion

"A logical question is whether TAVR is an alternative to surgical aortic valve replacement (SAVR) in patients deemed to be at low surgical risk," according to interventional cardiologist , of Denmark's Rigshospitalet.

"But how should we define a low-risk patient? One way is to use an STS score <4%, yet an 85-year-old male patient without comorbidities who generates a low score (1.8%) would already be offered TAVR at many institutions. Thus, it may be more interesting to pursue the role of TAVR patients with aortic stenosis who are not only at low surgical risk, but also at younger age – particularly due to a marked decrease in the age at which surgical bioprostheses are preferred at many sites," Sondergaard wrote in his .

Among the initial shortcomings of TAVR, paravalvular leak can be addressed with the routine use of cardiac CT for annulus sizing; new devices also have an outer skirt or adaptive seal that can reduce paravalvular leak.

Another weakness has been the association between TAVR and heart block with need for permanent pacemaker implantation: But operators can use a higher prosthesis implantation technique and opt for re-positional TAVR devices, he suggested.

As for the question of TAVR bioprosthesis durability raised by data from Danny Dvir, MD, of St. Paul's Hospital in Vancouver, "it is important to notice that these findings were observed in older patients using first-generation devices," Sondergaard argued, adding that TAVR degeneration was not limited to cases requiring reintervention in Dvir's report.

Ultimately, Sondergaard wrote, the only way to know if TAVR is right for lower-risk patients is to start generating the data now. "Although some of the earliest TAVR devices already have longer follow-up data than some of the newer surgical bioprostheses introduced to the market, the only way to get reliable longterm durability data is to introduce the therapy into younger, low-risk patients – preferably in randomized clinical trials against SAVR."

Surgeon Says Not So Fast

"As surgeons, involved in the surgical assistance of TAVR procedures or in the standby coverage in case of major complications, we have been reflecting on the implications of the interventionists' and on the potential drawbacks and real-life applicability of TAVR in lower-risk patients," , of Centre Cardiologique du Nord de Saint-Denis in France, and fellow surgeons wrote in a counterpoint commentary.

Acknowledging the strides that have been made in the field, Nappi and colleagues nonetheless made a point of the financial incentives driving TAVR expansion. "All the major randomized TAVR studies published disclosed sponsorships by the companies in the market and, considering the non-negligible financial interest and role of industries in this field, one could provocatively think that transcatheter devices companies have been effective in 'conquering' the cardiovascular departments of the hospitals around the world."

"This might lead to even more provocative considerations: To what degree is the clinical decision on TAVR actually influenced by the industrial push and financial injection? Could economical considerations be a driving force guiding the clinical indications? Does this [explain] the not-uniform geographical distribution across Europe (Germany, France, Italy, Spain, Portugal, Greece) of TAVR procedures?"

There may also be problems with TAVR in the hands of inexperienced operators, the surgeons commented, adding that increased transvalvular gradient and valvular hemodynamic degeneration are other problems that have not gone away even in the current TAVR era.

"The interesting field of sutureless surgical valves, although supported by consistent body of evidence, seems to have been overlooked or at least have struggled for respect compared to the attention given to TAVR," Nappi and colleagues wrote.

"We hope that with the expansion of TAVR procedures, more investigator-driven investigations will be produced in order to obtain less biased and more balanced comparisons."