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Ischaemic mitral regurgitation (MR) is defined as MR caused by changes of left ventricular structure and function related ultimately to ischaemia. However, the acute manifestation of MR following infarction (which usually presents as a haemodynamic crisis) is related to rupture or stretching of the papillary muscle, and is normally categorised with complications of infarction. The term ischaemic MR is usually understood to relate to chronic MR, occurring >2 weeks after infarction and in the absence of structural mitral valve disease. In terms of pathogenesis, this should be considered a disease of abnormal left ventricular (LV) shape and function with a valvular manifestation.
The frequency in ischaemic MR varies according to the technique used for its detection (being more common in echocardiographic than angiographic studies), the management of the patients (more common in non-revascularised patients), the timing post-myocardial infarction (MI) (more common early, before medical treatment is optimised), and infarct size. These selection influences were avoided in the study of a geographically defined MI incidence cohort in which MR was identified at 30 days in 50% of 773 patients, 12% of which were moderate or severe, and in whom the detection by physical examination was unreliable.1
Ischaemic MR is not only a common but also a serious finding. The community based study of ischaemic MR among 30 day survivors of MI showed moderate or severe MR to be associated with a threefold increase in the risk of heart failure and a 1.6-fold increased risk of death at 5 year follow-up independent of age, gender, ejection fraction (EF), and Killip class.1 Mortality was increased even with mild MR.2
Mechanisms of ischaemic MR
The mechanism of ischaemic MR requires a combination of both leaflet tethering and reduction of closing forces (table 1). The difficulty posed by separating the role of each component has been …