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WASHINGTON -- Newer-generation transcatheter heart valves have improved upon older models in their efficacy for patients with severe non-calcified native aortic regurgitation (AR), but much work remains to be done, according to a registry study presented here.

Off-label transcatheter aortic valve replacement (TAVR) was more likely to be successful when patients got newer-generation heart valves (82% versus 47% for first-generation valves CoreValve and Sapien XT, P<0.001). One component of device success, the incidence of residual moderate-to-severe AR, also numerically favored newer valves (96% versus 69%), reported Danny Dvir, MD, of Seattle's University of Washington.

The Valve Academic Research Consortium-2 (VARC-2) definition of early safety at 30 days favored neither group (74% versus 72%, P=0.88). However, VARC-2 clinical efficacy gave the edge to newer-generation devices once again (72% versus 56%, P=0.04) in terms of recipients having fewer combined strokes, mortalities, valve-related dysfunctions, residual AR, and severe heart failure, Dvir said in a presentation at the Cardiovascular Research Technologies meeting.

Even so, one-fifth of TAVR recipients ended up needing a new permanent pacemaker.

"Although significant improvement is seen with newer-generation transcatheter heart valve devices, TAVR for [native AR] is a challenging approach associated with limited procedural efficacy," Dvir concluded.

Dvir theorized that better clinical outcomes can be expected if patients were referred for the intervention at an earlier clinical stage. Additionally, new devices designed for aortic valve insufficiency might improve patient outcomes, he suggested.

"Patients with AR are a more heterogeneous patient population as compared to patients with degenerative aortic stenosis due to the wide etiological spectrum of AR. Dilatation of the aortic root and absence of valvular calcification complicate anchoring of the device and may call for alternative device designs. Alternative concepts and designs may be needed to treat these patients," agreed Thomas Pilgrim, MD, of Bern University Hospital in Switzerland.

"Alternative designs may anchor the valve to the native leaflets -- such as the JenaValve and the J-Valve. In addition, larger sized transcatheter heart valves will be needed as a significant number of patients with AR have a dilated aortic annulus that cannot be treated with currently available devices," added Pilgrim, who was not involved in the study.

There are no transcatheter devices indicated for isolated native AR in the U.S. Meanwhile, the JenaValve has the sole CE Mark for this indication in Europe.

"I do foresee that we will, hopefully, have dedicated devices for [native AR] patients," said Chandan Devireddy, MD, of Emory University Hospital Midtown in Atlanta.

His prediction was also that new devices would have to accommodate much larger aortic annuli and root dimensions. Leaflet technology would remain the same. "The key bioengineering focus would need to be on reliable stabilization and annular sealing to reduce risk of embolization and paravalvular leak," added Devireddy, who was not involved in the study.

Dvir's group included 254 cases in 2017, all identified from the VIVID registry. Degenerative AR accounted for 61% of cases. Mean age was 74 and the cohort was 54% men. Patients went into the procedure with an average of EuroSCORE II of 8.7% and a 6.5% Society of Thoracic Surgeons (STS) score. Mean left ventricular ejection fraction was 44.7%.

The study group tended to get general anesthesia and transfemoral access during TAVR. They stayed 4.2 days in the ICU on average (and 12.5 days total in the hospital).

Dvir's group found that the predictors of 1-year mortality were:

• Moderate-or-worse AR: HR 2.85 (95% CI 1.02-7.94)
• STS score >8%: HR 3.65 (95% CI 1.15-9.54)
• Acute kidney injury grade 2 or higher: HR 8.88 (95% CI 2.37-29.9)

"The study underscores that device malpositioning and residual AR represent the most important challenges in TAVR for native AR," according to Pilgrim. "The study indicates that there is a lower risk of device malpositioning and residual AR in patients treated with early, as compared to newer-generation devices, and corroborates the findings of previous reports."

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