Atrial Secondary Mitral Regurgitation Outcomes Following Mitral Transcatheter Edge-to-Edge Repair: Results From the EXPANDed Studies

BACKGROUND: Atrial secondary mitral regurgitation (aSMR) is a distinct subtype of SMR characterized by normal leaflets, annular dilatation, left atrial (LA) enlargement, and preserved left ventricular function. Treatment pathways for aSMR are undefined, and limited data exist regarding outcomes following mitral transcatheter edge-to-edge repair (MTEER). The analysis aimed to evaluate outcomes in patients with aSMR treated with MTEER from the EXPANDed (Evaluation of the MitraClip X System Post-MArket Real-World CliNical Outcomes Database ) studies. METHODS: One-year outcomes were assessed in patients from the EXPANDed studies (EXPAND and EXPAND G4 [Evaluation of the MitraClip X System Post-MArket Real-World CliNical Outcomes Database Generation 4 ]) who met criteria for aSMR. aSMR was defined by the presence of atrial fibrillation, left ventricular ejection fraction ≥45%, and at least 1 dilated LA parameter per echocardiographic core laboratory assessment: LA volume index, LA diameter, or LA diameter index. RESULTS: Of the 967 patients with SMR treated with MTEER in the EXPANDed data set, 160 (17%) met criteria for aSMR. Patients with aSMR were elderly (78±8 years), symptomatic (Kansas City Cardiomyopathy Questionnaire Overall Summary score, 48±27 pts), and had small left ventricular and large LA dimensions at baseline. Acute procedural success was achieved in 97.5% of patients with aSMR, with MR reduction to ≤1+ in 95.2% at 1 year. There were significant 1-year improvements in quality of life (+19 pt Kansas City Cardiomyopathy Questionnaire Overall Summary) and functional capacity (New York Heart Association I/II 80%). The 1-year all-cause mortality rate was 9%, with patients experiencing a 56% reduction in 1-year heart failure hospitalization rates from pre- to post-MTEER. CONCLUSIONS: In the largest population of patients with aSMR assessed by an echocardiographic core laboratory, MTEER safely and significantly reduced MR with improvements in quality of life and reduction in heart failure hospitalization through 1 year.