Mitral regurgitation is reported in three children with hyperthyroidism. The regurgitation was demonstrated by left-ventricular cineangiography in one patient, the first known case of demonstrated thyrotoxic mitral regurgitation. We propose that excess thyroid hormone induces intrinsic papillary muscle disease by its direct effects on the heart and circulation. Mitral regurgitation disappeared in these three patients two to ten months after hyperthyroidism was treated. Recognition of a mitral-thyrotoxicosis nexus is of help in the differential diagnosis of mitral regurgitation.
Reynolds JL, Woody HB. Thyrotoxic Mitral RegurgitationA Probable Form of Intrinsic Papillary Muscle Dysfunction. Am J Dis Child. 1971;122(6):544–548. doi:10.1001/archpedi.1971.02110060114022