Optimal Implantation Depth Not Met in Majority of TAVR Procedures

Optimal implantation depth (ID) was found to be achieved in <30% of transcatheter aortic valve replacement (TAVR) procedures, according to a study published in JACC: Cardiovascular Interventions.

Performing TAVR with the optimal ID is likely to influence clinical outcomes in patients. As there is no standardized method to assess ID, an array of approaches to calculate ID is used in daily practice, thus hampering the reliability of ID reporting in clinical trials. Investigators sought to compare 3 different approaches in terms of their relationships with post-TAVR outcomes, in a first of its kind study.

A total of 258 patients (mean age, 80.8 years; 68.6% women) with severe, symptomatic aortic stenosis and considered to be at high surgical risk were included in this study. Patients underwent transfemoral TAVR with a third-generation self-expanding device (Medtronic Core Valve Evolut R^TM).  Clinical and hemodynamic outcomes were prospectively evaluated in study participants. At baseline, the mean pressure gradient was 38.1±16.6 mm Hg, the mean aortic valve area was 0.6±0.2 cm², and the mean aortic annulus perimeter was 74.5±6.6 mm in this cohort.

Three different methods were used to calculate ID: the arithmetic mean method uses the mean of the distances between the distal end of the prosthesis and the noncoronary and left coronary cusp (NCC and LCC, respectively). The NCC distance approach takes into account only the distance between the NCC and the distal prosthesis end; the deepest edge method uses the deepest edge of the prosthetic distal end.

The study’s primary outcome was the rate of pacemaker implantation after TAVR. Secondary outcomes were mean pressure gradient reduction and occurrence of aortic regurgitation and paravalvular leakage post-TAVR. The median follow-up time was 42.5 days, and the 30-day mortality rate was 1.6%.

In this cohort, the optimal ID was achieved in <30% of procedures, regardless of the methodology used to calculate it. Use of the arithmetic mean, the NCC distance, and the deepest edge approaches yielded optimal ID in 25.4%, 28.4%, and 20.5% of cases, respectively. The rate of optimal ID attainment was different, based on the calculation method used (P =.008). This difference was driven largely by differences between the arithmetic mean and deepest edge methods (P =.006) and between the deepest edge and NCC distance methods (P =.015).

The pacemaker implantation rate was lower in patients in whom the optimal ID was vs those in whom it was not reached (3.7% vs 14.6%, respectively; P =.033), as was the aortic regurgitation index (20.8 vs 25.1, respectively; P =.001). There was no significant difference in mean pressure gradient reductions when optimal ID was vs was not reached (7.4 vs 8.3 mm Hg, respectively; P =.093).

Study limitations include a small sample size and single-center setup.

“A consistent definition with practical applicability in daily clinical practice would probably increase the reporting of the ID in clinical studies. This report should draw attention to this omitted parameter, which is left out of the highly standardized outcome reports of TAVR patients,” noted the authors. They recommended that future research involve larger trials and different devices and that ultimately a uniform assessment method be established for determination of optimal ID.

Reference

Piayda K, Hellhammer K, Veulemans V, et al. Navigating the “optimal implantation depth” with a self-expandable TAVR device in daily clinical practice. JACC Cardiovasc Interv. December 2019. doi: 10.1016/j.jcin.2019.07.048