Moderate ischemic mitral regurgitation: novel diagnostic tools and the evolution of treatment approaches

Moderate ischemic mitral regurgitation (IMR) remains a ‘grey area’ for clinicians, with evidence-based decision-making for patients referred for coronary artery bypass grafting (CABG) being particularly challenging. IMR results from left ventricular remodeling and subvalvular deformation, not primary leaflet pathology. Even moderate regurgitation (effective regurgitant orifice area 20–39 mm2) is associated with a 1.5–2-fold increased risk of death. Among diagnostic methods, stress echocardiography is valuable but underutilized. An exercise-induced increase in the effective regurgitant orifice area of ≥ 13 mm2 or an absolute value ≥ 30 mm2 identifies patients with prognostically significant dynamic regurgitation requiring valve intervention, despite moderate resting values. Most randomized trials, particularly the Cardiothoracic Surgical Trials Network study, show that adding mitral valve annuloplasty to CABG reduces regurgitation severity but does not improve two-year survival or heart failure hospitalization rates, resulting in only a class IIb recommendation for the combined procedure. Modern imaging techniques, including three-dimensional echocardiography and cardiac magnetic resonance, provide added value in assessing IMR, annular geometry, and myocardial viability. Natriuretic peptides offer additional prognostic information. Transcatheter percutaneous mitral valve repair (‘edge-to-edge’) shows promise in high-risk patients and opens new prospects for hybrid revascularization. Optimal medical therapy, including Sacubitril/Valsartan and SGLT2 inhibitors, may slow IMR progression through enhanced reverse remodeling. In the absence of convincing evidence for any single approach, the current standard remains an individualized strategy implemented by the Heart Team, simultaneously considering clinical status, stress echocardiography data, anatomical characteristics, and surgical risks. Future research priorities include standardization of stress echocardiography protocols, validation of prognostic models, and long-term assessment of transcatheter approach outcomes in this complex patient category.