Residual Mitral Regurgitation After Surgical Mitral Valve Repair and Long-Term Recurrence and Reintervention

Abstract

Surgical mitral valve repair is the preferred treatment for degenerative mitral regurgitation (MR) and is also widely performed for MR of other etiologies; however, recurrent MR after repair is not uncommon and is associated with adverse left ventricular remodeling and increased risks of mitral valve reintervention and death. At the completion of repair, a small amount of residual MR is frequently detected on intraoperative transesophageal echocardiography or predischarge transthoracic echocardiography, and whether mild residual MR is acceptable remains clinically controversial. Existing evidence derives largely from single-center studies with limited sample sizes, and the timing of residual MR assessment, grading thresholds, and outcome definitions vary considerably across studies, limiting the generalizability of their conclusions. We therefore plan to conduct a systematic review and meta-analysis. PubMed/MEDLINE, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) will be systematically searched for English-language studies of adults undergoing surgical mitral valve repair for MR of any etiology that report residual MR grade and long-term follow-up outcomes. The primary outcomes are recurrent MR (≥ moderate MR during follow-up) and mitral valve reintervention (surgical or transcatheter). In the primary analysis, adjusted hazard ratios will be pooled using random-effects models; unadjusted estimates will be pooled separately as supplementary analyses and will not be combined with adjusted estimates. Pooled estimates will be obtained separately for different residual MR thresholds (≥ mild vs. none/trace; > mild vs. ≤ mild). Subgroup analyses will be performed according to MR etiology (degenerative vs. other or mixed etiologies) and timing of residual MR assessment (intraoperative vs. early postoperative/predischarge vs. not specified), and the association of residual MR with long-term mortality will also be explored. Because death precludes subsequent reintervention, we will record whether included studies accounted for competing risks, and cause-specific and subdistribution hazard ratios will be pooled together in the primary analysis, with the measure type examined as a subgroup factor and a sensitivity analysis restricted to cause-specific hazard ratios. These analyses will be complemented by risk-of-bias assessment, sensitivity analyses (including recurrent MR defined as ≥ moderate-to-severe MR and reintervention restricted to surgical reoperation), and grading of the certainty of evidence. This study is expected to clarify the prognostic value of residual MR, particularly mild residual MR, thereby providing evidence to inform whether surgeons should aim for no or trace residual MR intraoperatively, whether a second pump run for re-repair is warranted, and how high-risk patients should be stratified for postoperative surveillance, as well as offering a reference for standardizing the definition and reporting of residual MR in future studies.