Paroxysmal Severe Mitral Regurgitation

To investigate the clinical presentation, pathophysiology, and treatment for "paroxysmal severe mitral regurgitation" (MR), which is an underappreciated cause of heart failure with preserved left ventricular ejection fraction.

We retrospectively reviewed cases of transient severe MR that were evaluated at Mayo Clinic in Rochester, Minnesota, between January 1, 2006, and December 31, 2019. Paroxysmal severe MR was defined as the appearance of transient severe MR in patients with mild MR at rest, normal left ventricle (LV) size, left ventricular ejection fraction greater than 40%, and absence of obstructive coronary artery disease.

We identified 6 patients (5 women) with a median age of 68 years. There were 3 distinct mechanisms of paroxysmal severe MR, which we labeled types 1, 2, and 3. Type 1 MR was caused by LV dyssynchrony from a rate-dependent left bundle branch block, which led to apical leaflet tenting and incomplete coaptation. Type 2 MR occurred from mitral annular dilatation during maneuvers that increased left-sided volume. Type 3 MR was caused by coronary artery vasospasm with apical leaflet tenting. Treatments varied depending on the underlying cause and included cardiac resynchronization therapy for type 1, surgical valve replacement for type 2, and medical therapy for type 3.

Paroxysmal severe MR is a rare cause of heart failure in patients with preserved LV function. We have identified 3 distinct mechanisms that can lead to this dynamic process, with treatments varying based on the underlying cause.