A Rare Case of Left Ventricular Outflow Tract Obstruction 18 Years after a Mechanical Mitral Valve Replacement

Background: Left ventricular outflow tract (LVOT) obstruction is a serious complication that can occur after various mitral-valves, surgical or percutaneous, interventions. It was rarely described in mechanical mitral valve replacements. Aim: to describe a rare case of late LVOT obstruction after a mitral valve replacement by a low-profile mechanical prosthesis. Case Presentation: A 48-year woman, with a history of rheumatic mitral valve disease and mechanical mitral replacement by a hemi-disc valve 18 years ago, presented for a recent dyspnea. Echocardiography showed a narrowing of the LVOT, with anterior position of the mitral prosthesis, aorto-mitral annular angulation, septal thickening and remnant native sub-valvular tissue attached to the septum in the LVOT region. This resulted in LVOT obstruction with a peak gradient of 75 mmHg. The heart team opted for a redo surgery, but the surgical decision was refused by the patient. Discussion: This is a rare case of late LVOT obstruction after mitral valve replacement by mechanical low-profile prosthesis. Preserved native mitral valve tissue, which is the main described cause of LVOT obstruction after mechanical mitral valve replacements was not the unique cause of obstruction in this patient who had also a septal thickening and anterior prosthetic position. Aorto-mitral annular angulation that was identified as a risk factor of LVOT obstruction after trans-catheter mitral valve replacements, should be, probably, also took into account and assessed pre-operatively in patients undergoing surgical mitral replacements. Conclusion: LVOT obstruction can occur after mechanical mitral replacements event with low profile prosthesis. In patients with identified risk factors of LVOT obstruction, preservation mitral anterior leaflet should be avoided, and preservation of other native mitral tissue should be discussed.