Mechanistic insights into transient severe mitral regurgitation.

Acute mitral regurgitation (AMR), a known complication of acute coronary syndromes, is usually associated with posterior papillary muscle dysfunction/rupture. In severe cases, management of AMR requires surgical intervention. Reversible severe AMR in patients in the absence of left ventricular systolic dysfunction and coronary artery stenosis may result from processes which cause transient subendocardial ischemia, such as intermittent episodes of hypotension or coronary artery vasospasm. We present two cases of reversible transient AMR due to subendocardial and/or endocardial ischemia, both of which offer insight into the mechanism of transient severe AMR.