MYOCARDIAL DAMAGE DOES NOT OCCUR IN UNTREATED HYPERTHYROIDISM UNLESS ASSOCIATED WITH CONGESTIVE-HEART-FAILURE

Even in the absence of underlying cardiac disease, hyperthyroidism has seldom been reported to be associated with left ventricular dysfuncti on and congestive heart failure. The left ventricular function invaria bly improves with achievement of euthyroid status. Anecdotal autopsy r eports have suggested that myocardial necrosis associated with hyperth yroidism may be responsible for congestive heart failure. This study p rospectively evaluates the role of myocardial necrosis in untreated hy perthyroidism by imaging with Indium-111 antimyosin antibody. Thirteen consecutive patients (7 men and 6 women, mean age 36 +/- 11 years) wi th hyperthyroidism and Graves' disease (10 patients), subacute thyroid itis (2 patients), or multinodular goiter (1 patient) formed the basis of the study. The T4 levels ranged from 33 to 183 pmol/L (mean 103 +/ - 47 pmol/L) and cardiac output from 5.47 to 11.0 L/min (mean 717 +/- 1.75 L/min). Two patients had clinical congestive heart failure and mi ldly depressed left ventricular ejection Fraction. Both patients had s cintigraphic evidence of myocardial damage with abnormal antimyosin sc ans. In the remaining 11 patients with normal left ventricular ejectio n fraction, no antimyosin uptake was observed. The reevaluation of two patients with abnormal initial scans 6 to 8 months after treatment re vealed euthyroid status, resolution of antimyosin uptake, and normaliz ation of left ventricular function. This study indicates that myocardi al necrosis may be detected in a smell proportion of patients with hyp erthyroidism. which could contribute to left ventricular systolic dysf unction.