功能性二尖瓣反流的机制表型、影像评估与治疗策略进展
Mechanistic Phenotypes, Imaging Assessment, and Therapeutic Strategies in Functional Mitral Regurgitation

功能性二尖瓣反流(Functional Mitral Regurgitation, FMR)是继发于心腔及二尖瓣结构重构的常见瓣膜病变。与原发性二尖瓣反流不同，FMR患者瓣叶本身多无明显脱垂、裂隙、感染或退行性破坏，其核心病变在于左心室、左心房、二尖瓣环、乳头肌和腱索之间的几何关系及力学平衡发生改变。传统观点多将FMR归因于左心室扩大、乳头肌移位和瓣叶拴系，但现有研究显示，FMR具有明显的机制异质性，可根据主导病变部位分为室性FMR、房性FMR和混合型FMR。与此同时，二尖瓣瓣叶并非完全被动受累，在长期牵拉、缺血和炎症环境下可发生适应性增大、纤维化及僵硬等重塑改变，进一步影响瓣叶对合和反流进展。三维超声、经食管超声和心脏磁共振等影像技术的发展，使FMR评估逐渐从单纯判断反流程度，转向对反流机制、心腔重构程度、瓣叶拴系情况及解剖适配性的综合分析。COAPT、MITRA-FR、RESHAPE-HF2和MATTERHORN等研究结果也提示，FMR患者能否从经导管缘对缘修复或外科治疗中获益，取决于机制表型、基础心脏病控制情况、左心室重构程度、反流严重程度及手术风险等多种因素。本文围绕FMR的机制表型、瓣叶重塑、影像评估及治疗策略进行综述，以期为临床分层管理和个体化治疗提供参考。
Functional Mitral Regurgitation (FMR) is a common valvular disorder secondary to remodeling of the cardiac chambers and mitral valve apparatus. Unlike primary mitral regurgitation, FMR usually occurs in the absence of intrinsic leaflet prolapse, cleft, infection, or degenerative destruction. Its central mechanism lies in altered geometry and mechanical balance among the left ventricle, left atrium, mitral annulus, papillary muscles, and chordae tendineae. Traditionally, FMR has been attributed mainly to left ventricular dilatation, papillary muscle displacement, and leaflet tethering. However, current evidence indicates that FMR is a heterogeneous syndrome that can be classified into ventricular FMR, atrial FMR, and mixed FMR according to the predominant site of remodeling. In addition, mitral leaflets are not entirely passive structures. Under chronic tethering, ischemic injury, and inflammatory stimulation, they may undergo adaptive enlargement, fibrosis, and stiffening, thereby influencing leaflet coaptation and the progression of regurgitation. Advances in three-dimensional echocardiography, transesophageal echocardiography, and cardiac magnetic resonance have shifted the assessment of FMR from simple grading of regurgitation severity to integrated evaluation of regurgitation mechanisms, chamber remodeling, leaflet tethering, and anatomical suitability for intervention. Evidence from COAPT, MITRA-FR, RESHAPE-HF2, and MATTERHORN also suggests that the benefit of transcatheter edge-to-edge repair or surgical treatment depends on mechanistic phenotype, optimization of underlying cardiac disease, degree of left ventricular remodeling, regurgitation severity, and procedural risk. This review summarizes the mechanistic phenotypes, leaflet remodeling, imaging assessment, and therapeutic strategies of FMR, aiming to provide a reference for clinical stratification and individualized treatment.