Patient-tailored computational fluid dynamics models for assessing the effect of transcatheter edge-to-edge repair devices on mitral regurgitation flow convergence.

Transcatheter edge-to-edge repair (TEER) devices change the direction of blood flow convergence, leading to errors in the calculation of the effective regurgitant orifice area (EROA) via the proximal isovelocity surface area (PISA) method during and after the TEER procedure; in turn, this affects intraoperative decision-making and postoperative follow-up treatment plans. This study aimed to quantify the influence of TEER devices on PISA geometry and EROA calculation using patient-specific computational fluid dynamics (CFD) models and to develop a correction approach for the more accurate assessment of residual mitral regurgitation. For 38 patients undergoing TEER, individualized CFD models for post-TEER mitral regurgitation were constructed based on the multimodal fusion of cardiac computed tomography (CT) and three-dimensional transesophageal echocardiography. The distance from the midpoint of the mitral regurgitation orifice to the TEER device (recorded as D) was measured. The TEER devices were then removed from the CFD models. The PISA radius with and without the TEER device was measured, and the corresponding EROA1 and EROA2 were calculated. The EROA correction coefficient (CC) was calculated as follows: CC = EROA2/EROA1. A total of 49 CFD model sets of post-TEER for mild-or-greater residual mitral regurgitation were constructed, with 57 sets of PISA. According to the relative position of PISA and the TEER device, four types of PISA were observed: Type 1 included PISA located far from the TEER device (15 cases; CC: 0.93±0.07); Type 2 included PISA adjacent to the TEER device (37 cases; CC: 0.65±0.10); Type 3 included PISA inside the TEER device (3 cases; with CCs of 1.81, 2.72, and 1.06, respectively); and Type 4 included PISA between two TEER devices (2 cases; with CCs of 0.30 and 0.31, respectively). In Types 1 and 2 PISA, D and CC were significantly correlated (R=0.88; P<0.001), and the calculation of EROA could be corrected with the following formula: CC = 0.52 × D + 0.53. Individualized CFD models can be used to assess the impact of TEER devices on PISA. For types 1 and 2 PISA, CCs based on echocardiography data can be applied to reduce or eliminate the influence of TEER devices on the calculation of EROA.