Clinical manifestations, diagnosis, and treatment of ischemic mitral regurgitation: a review

Ischemic mitral regurgitation (IMR) is a subtype of secondary MR, which is caused as a complication of ischemic heart disease. Valvular involvement can be primary (organic) or secondary (functional). Primary IMR happens after the rupture of the mitral subvalvular apparatus in the context of an acute myocardial infarction (AMI). Secondary IMR occurs when the valve leaflets and chordae are structurally normal and MR results from an imbalance between closing and tethering forces on the mitral valve (MV) secondary to alterations in the left ventricular (LV) geometry (1,2). In both cases, IMR is associated with a critical obstruction (>70%) of at least one main coronary vessel (3). It is most commonly seen in ischemic cardiomyopathies. The degree of annular dilatation is much less in IMR than in degenerative MR (4). The anatomical and physiopathological mechanisms that originate IMR have not been fully clarified. However, remodelling of the LV related to severe myocardial ischemia is the main factor that induces the lesion, together with the involvement of the papillary muscles (PM). Therefore, its cause is an affectation of the mitral valvular spatial disposition, due to the involvement of the LV or because of an intrinsic affectation of it by coronary ischemic heart disease. The PM displacement that creates greater tension of the leaflets is posterolateral-apical, which explains why a located inferior AMI can produce a significant IMR, and why its incidence is much lower in the anterior AMI (2). Identifying the etiology of MR in ischemic heart disease is not easy, since a significant percentage of patients have previously shown MR of degenerative origin (5)