Flail Mitral Valve: A Rare Complication of a Thyroid Storm

OBJECTIVE: Thyroid storm is a life-threatening presentation, with heart failure and tachyarrhythmias being common manifestations. This case highlights that a flail mitral valve from chordae tendineae rupture can be a cause of worsening heart failure and cardiogenic shock in a thyroid storm, albeit a rare complication. METHODS: We describe a patient who was admitted for a thyroid storm precipitated by pneumonia, who later developed an acute flail mitral valve from chordae tendineae rupture. RESULTS: A 55-year-old woman with no past medical history was admitted with fever, dyspnea, lower limb swelling, and hemoptysis. She was febrile, tachycardic, and in fluid overload. Her heart sounds were dual, and no murmurs were heard. Initial investigations indicated primary hyperthyroidism and pneumonia. She was diagnosed with a thyroid storm precipitated by pneumonia, complicated by heart failure. Her Burch-Wartofsky score was 70. She was started on intravenous hydrocortisone, oral propylthiouracil, oral Lugol's iodine, and oral cholestyramine, together with intravenous amoxicillin-clavulanate and intravenous furosemide. She continued to deteriorate in the medical intensive care unit, with worsening hypoxia and hypotension. Echocardiography showed an acute flail posterior mitral valve leaflet with torrential mitral regurgitation from rupture of the chordae tendineae. She subsequently underwent a bioprosthetic mitral valve replacement. CONCLUSION: An acute flail mitral valve precipitated by thyroid storm leading to refractory cardiogenic shock is rare. Factors contributing to the rupture of valve chordae tendineae include the effect of hyperthyroidism on papillary muscle function, a hyperdynamic circulation leading to vulvular stress, as well as pre-existing mitral valve pathology.