Large Field-of-View Intravascular Ultrasound for Mitral and Tricuspid Valve-in-Valve Guidance: A Pilot Study

BACKGROUND: Actual expansion of a transcatheter heart valve (THV) might differ from nominal, particularly during nonaortic valve-in-valve for a degenerated bioprosthetic surgical heart valve (SHV). This pilot study compared THV expansion measured using large-field-of-view intravascular ultrasound (IVUS) vs. multi-slice computed tomography (MSCT) and assessed the correlation between THV dimensions and transvalvular gradients.

METHODS: Fourteen patients were successfully treated with mitral/tricuspid valve-in-valve SAPIEN 3 implantation sized using the true SHV inner diameter; all 14 had baseline MSCT and transvalvular gradients measured at baseline, postprocedure, and at discharge. Periprocedural IVUS (in 6 patients using a Philips 10MHz Vision PV035) was compared with postprocedural MSCT (in 9 patients) with offline measurements performed at 1-mm steps along the THV height. Overall, 190 MSCT and paired 124 IVUS cross-sections were analyzed.

RESULTS: There was very good agreement between IVUS THV dimensions and corresponding MSCT measurements (intraclass correlation coefficient ≥0.986 and p < 0.001). IVUS measured THV expansion (percent of the nominal cross-sectional area) was smaller within the inflow and middle of the THV overlapping the ring (85.9% ± 11.3%, 83.8% ± 11.8%) than within the outflow (98.8% ± 12.7%). The residual mean transvalvular gradient increased from periprocedural to predischarge (3.5 ± 2.0 vs. 6.3 ± 1.7 mmHg, p < 0.001). The only independent predictor of predischarge maximal transvalvular gradient was the smallest minimal inner THV frame diameter (r 2 = 0.67), predicted by true SHV internal diameter (Beta = 0.066, 95% CI = 0.015-0.117, r 2 = 0.49, p = 0.037).

CONCLUSIONS: This pilot study is the first to report the feasibility of a large field-of-view IVUS for periprocedural measurement of actual THV expansion when deployed valve-in-valve. Minimal inner THV stent frame dimensions correlate with increased postprocedural transvalvular gradients.