Residual Mitral Regurgitation Interacts With Transmitral Mean Pressure Gradient to Modify the Association With Mortality Following Transcatheter Edge-to-Edge Repair.

Background: The association, if any, between the transmitral mean pressure gradient (TMPG) after mitral transcatheter edge-to-edge repair and 1-year mortality is controversial in patients undergoing mitral transcatheter edge-to-edge repair with the MitraClip system. We sought to estimate the association between intraoperatively measured residual mitral regurgitation (rMR) and TMPG and 1-year mortality among patients undergoing mitral transcatheter edge-to-edge repair to facilitate decisions on additional devices.

Methods: In patients with severe secondary (functional) MR, we analyzed registry data using generalized estimating equations. Both rMR and TMPG were nonlinearly transformed using fractional polynomials.

Results: We studied 570 patients with secondary MR who underwent mitral transcatheter edge-to-edge repair in 11 centers. Most patients were men (61%) and averaged 72±12 years of age. Most (78%) patients had TMPG <5 mm Hg and 22% had TMPG ≥5 mm Hg. Postprocedural MR severity improved substantially, being ≤2+ in 95% (with ≤1+ in 76%), 3+ in 3%, and 4+ in 2%. 1-year mortality was 20%. After adjustment for confounders, rMR (odds ratio, 2.10 [95% CI, 1.88-2.35]; P<0.001 for rMR^.5) and TMPG remained associated with mortality, with odds ratios of 1.26 (95% CI, 1.19-1.32), 1.84 (1.58-2.10), and 3.13 (2.31-3.98) for TMPG values of 4, 6, and 8, respectively, compared with TMPG=2 mm Hg at rMR=1+.

Conclusions: Both rMR and TMPG were nonlinearly associated with 1-year mortality. At low levels of rMR, changes in TMPG are associated with only small changes in the risk of death. Conversely, at higher levels of rMR, even small changes in TMPG are associated with larger changes in the absolute risk of death.