乌鸦传媒

PARIS -- Bioprosthetic devices used in transcatheter aortic valve replacement (TAVR) appeared to keep working years after implantation, researchers reported here, though caveats in their methodologies left bioprosthesis durability still under question.

A post hoc analysis wherein investigators looked for valve dysfunction and failure in the NOTION trial showed that bioprosthetic valve dysfunction was numerically lower in TAVR group over 5 years (55.4% versus 65.2%, P=0.10).

Neither group had any intra-prosthetic aortic regurgitation or valve thrombosis. There were no difference in non-structural valve deterioration (54.0% versus 57.8%, P=0.52) or endocarditis (4.3% versus 5.9%, P=0.55), according to Lars Sondergaard, MD, DMSc, of Rigshospitalet in Copenhagen, and colleagues at the EuroPCR meeting.

His group defined bioprosthetic valve dysfunction as:

• Structural valve deterioration (large gradients, gradient increase, or intra-prosthetic aortic regurgitation)
• Non-structural valve deterioration (patient-prosthesis mismatch or paravalvular regurgitation)
• Bioprosthetic valve thrombosis; or endocarditis

Sondergaard noted that structural valve deterioration rates substantially favored TAVR at 3.9% versus 26.1% for surgical aortic valve replacement (SAVR, P<0.0001). Here the difference lay solely in elevated gradients among SAVR patients.

Bioprosthetic valve failure -- defined as valve-related death, aortic valve re-intervention, or severe structural valve deterioration in terms of gradients and aortic regurgitation -- turned up no differences between TAVR and SAVR groups at 5 years (8.5% versus 9.5%, P=0.89).

"Excellent hemodynamic valve performance was maintained. Bioprosthetic failure was low and similar for the self-expanding transcatheter and the surgical valves implanted," Sondergaard stated.

NOTION randomized lower-risk patients to SAVR or TAVR with the CoreValve. The multicenter trial previously reported comparable death rates at 5 years, with TAVR beating SAVR in valve performance (larger effective orifice areas and reduced gradients achieved).

Included was an all-comers population of patients over age 70 (n=280). Study limitations included the lack of a core lab for echocardiographic assessment.

Valve-Related Adverse Events

Separately, TAVR valves were infrequently linked to adverse events, according to an Italian registry study.

The ClinicalService Project, an Italian registry of consecutive patients who got TAVR with the CoreValve classic and Evolut R devices, revealed a prosthesis-related event rate of 3.2%, reported Luca Testa, MD, PhD, of IRCCS Policlinico San Donato in Italy, at the same EuroPCR session. Each year saw 0.2% to 1.5% of TAVR patients experiencing prosthesis-related cardiac deaths and hospitalizations.

"Our data suggest a very low rate of 'clinically relevant' bioprosthesis failure, and provide evidence about a reassuring long-term performance," he said.

There were 20 events over 7 years: 6 fatalities (3 from endocarditis, 1 bioprosthesis regurgitation after 6 years, 2 severe stenosis after 2 years and 7 years) and 14 re-hospitalizations. At the same time, all-cause mortality reached 68.1%.

Testa's group reviewed the files of 2,343 patients enrolled at 13 Italian centers (average age 82). The mean follow-up was 22 months.

There were no valve-related events between 7 and 9 years, while mild and moderate paravalvular leaks stayed stable from discharge to last follow-up.

Keep Calm and Carry On?

"These are obviously very important results since long-term durability of TAVR valves is a major question in the field," said Dharam Kumbhani, MD, of UT Southwestern in Dallas, who was not part of either study.

Regarding the 22-month follow-up in the Italian registry, he told 乌鸦传媒: "To me, the issue of long-term durability really begins after 5 years. Up to 5 years, we have pretty robust evidence from clinical trials and large registries that these valves appear to function pretty well with low structural valve deterioration rates."

Kumbhani added that the 68.1% death rate was high. "This brings up the issue of competing risks in this elderly population. If they die from non-cardiac causes within 5 years, it is unknown if they would have experienced structural valve deterioration beyond 5 years. This issue is particularly important when extrapolating these data to younger populations."

He expressed surprise at the fact that the NOTION investigators reported so few valve-related deaths at 5 years, given that they showed at 1 year a 16% rate of moderate-to-severe paravalvular leak (compared with 1% for SAVR), which predicts a worse prognosis in the long run.

"I think these data add to our understanding of long-term durability of these valves, but none of the studies so far have presented a complete and generalizable result, in my opinion. This issue is obviously critical for lower risk patients and clinical trials specifically addressing this issue, many of which are ongoing, will be very important."

"Both the technology of TAVR platforms and the procedural technique itself has evolved dramatically just in the past 5 years. Thus, it is difficult to extrapolate current long-term data to today's TAVR patients 5 years forward. Our hope, however, is that improvements in technology and technique will provide even better performance long term," pointed out Chandan Devireddy, MD, of Emory University Hospital Midtown in Atlanta.

Kumbhani and Devireddy both suggested that the two studies won't be changing practice anytime soon.