A Comprehensive Deep-Dive on Secondary Mitral Regurgitation

In the special April issue of JACC Imaging focusing on secondary mitral regurgitation (SMR), a number of articles on outcomes after transcatheter edge-to-edge repair (TEER) are reported. Specifically, the concept of proportionate vs disproportionate SMR was explored. Studies evaluated proportionality of SMR based on effective regurgitant orfice area (EROA) to left ventricular end-diastolic volume (LVEDV) and found a lower ratio (i.e., more proportionate SMR) had reduced benefit after TEER. Similarly, the ratio of regurgitant volume to LVEDV was found to impact survival with only medical therapy among those with high ratio, but benefit was observed after TEER. Yet, in MITRA-FR randomized trial, neither of these 2 parameters were predictive of outcomes after TEER vs optimal guideline-directed medical therapy (GDMT). Another concept looking total leaflet area to annular area ratio showed that a reduced ratio was associated with suboptimal MR reduction after TEER, likely due to inadequate coaptation reserve. In a study evaluating atrial SMR, a relatively new entity suggesting SMR due to left atrial enlargement and type 1 dysfunction, outcomes were poor except when surgery was performed. An important article on echo evaluation of MR was also presented, as well as CT evaluation of neo-LVOT on evaluation of anatomic feasibility of transcatheter mitral valve replacement (TMVR). Overall, this is a must-read issue from JACC Imaging if you want to learn the latest on research into SMR.