Eclipsed Mitral Regurgitation: A New Form of Functional Mitral Regurgitation for an Unusual Cause of Heart Failure with Normal Ejection Fraction

Background: Transient functional mitral regurgitation (MR) has never been reported as a cause of heart failure (HF) with normal ejection fraction (EF) in the absence of epicardial coronary artery stenosis. Results: Performance of echocardiography in patients with acute HF before initiation of HF medical treatment allowed identification of three patients with normal EF but transient massive functional MR during the HF episode. In all patients, massive MR occurred as a consequence of sudden extreme apical tenting of both leaflets with total lack of coaptation, despite normal EF and absence of detectable left ventricular (LV) remodeling, and despite absence of significant stenosis on coronary arteries. In all patients MR was triggered by methylergonovine injection and was reversible either spontaneously or after nitroglycerine administration, leaving patients with normal echocardiogram between HF episodes. In two patients, long-term administration of calcium channel blockers prevented recurrences of MR and HF, whereas in one, mitral valve was eventually replaced. Conclusion: Sudden reversible apical tenting of mitral leaflets with subsequent torrential MR and acute HF can occur despite normal EF, absence of pre-existing LV remodeling and absence of coronary artery stenosis. This atypical type of functional MR is an unusual mechanism of HF in patients with normal LVEF.