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Classification of mitral regurgitation
The origin of mitral regurgitation (MR), independent of the lesion type, lies in reduced coaptation between the valve leaflets which normally assure mitral valve competence.
The European Society of Cardiology (ESC) has issued guidelines that classify this disorder as either primary (organic) or secondary (ischaemic and functional) MR.1 In primary MR it is the valve itself which is at the origin of the problems, while in the case of secondary MR, it is the left ventricle (LV) that has sustained previous damage due to a myocardial infarction or dilated cardiomyopathy, resulting in annular dilatation and lateral displacement of the papillary muscles causing mitral valve insufficiency.1 Ischaemic MR results from a restriction of the mitral leaflets due to tethering of the subvalvular apparatus in an LV affected by ischaemia, while functional MR is secondary to changes in LV geometry resulting from LV dysfunction (as observed in idiopathic or ischaemic cardiomyopathy with severe LV dysfunction).1
Treatments and surgical indications vary considerably between those with primary and secondary MR. However, different existing classifications of MR according to mechanisms, causes, and mitral leaflet motion can nevertheless be a potential source of confusion due to overlapping terminology (table 1).w1 MR can be divided into primary and secondary types (as proposed by ESC guidelines) and can be further subclassified based on the leaflets' movement (Carpentier's classification, figure 1) or the causes of cardiomyopathy (table 1). Secondary MR can be both ischaemic or non-ischaemic in nature and can be characterised by a normal movement of the leaflets with annular dilatation (Carpentier type I) or systolic restriction and tethering of the mitral leaflets secondary to LV dysfunction (Carpentier type IIIb).