Large field-of-view intravascular ultrasound for actual valve-in-valve transcatheter heart valve expansion. A Pilot study.

Abstract

Abstract Background. Actual expansion of a transcatheter heart valve (THV) might differ from nominal particularly during non-aortic valve-in-valve (VIV) for degenerated bioprosthetic surgical heart valve (SHV). Aims. To compare THV expansion measured using large-field-of-view intravascular ultrasound (IVUS) versus multi-slice computer tomography (MSCT) and assess the correlation between THV dimensions and transvalvular gradients. Methods. Fourteen patients were successfully treated with mitral/tricuspid VIV SAPIEN 3 implantation sized using the true SHV inner diameter; all 14 had baseline MSCT and transvalvular gradients measured at baseline, post-procedure, and at discharge. Peri-procedural IVUS (in 6 patients using with a Philips 10MHz Vision PV035) was compared with post-procedural MSCT (in 9 patients) with offline measurements performed at 1-mm steps along the THV height, and analyzed 190 MSCT and paired 124 IVUS cross-sections. 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 peri-procedural to pre-discharge (3.5±2.0 vs 6.3±1.7mmHg, p<0.001). The only independent predictor of pre-discharge maximal transvalvular gradient was the smallest minimal inner THV frame diameter (r2=0.67), predicted by true SHV internal diameter (Beta = 0.066, 95%CI = 0.015 – 0.117, r2=0.49, p=0.037). Conclusions. Peri-procedural use of a large field-of-view IVUS offers accurate insight into actual THV expansion when deployed valve-in-valve. Minimal inner THV stent frame dimensions correlate with increased post-procedural transvalvular gradients.