Takotsubo Cardiomyopathy Associated with Levothyroxine Over-replacement

Area of Science:

• Cardiology
• Endocrinology
• Internal Medicine

Background:

• Takotsubo cardiomyopathy (TC) is an acute cardiac condition often triggered by stress.
• Previous reports linked TC to Grave's disease and exogenous thyrotoxicosis.
• Iatrogenic hyperthyroidism from levothyroxine over-replacement has not been previously reported as a cause of TC.

Observation:

• Two female patients presented with precordial pain and electrocardiographic changes suggestive of acute coronary syndrome.
• Both patients were on levothyroxine replacement therapy for autoimmune thyroiditis and had suppressed thyroid stimulating hormone (TSH) levels.
• Cardiac investigations revealed apical hypokinesis and elevated cardiac biomarkers, with no significant coronary artery disease.

Findings:

• The patients were diagnosed with Takotsubo cardiomyopathy secondary to levothyroxine over-replacement-induced hyperthyroidism.
• Apical hypokinesis resolved, and cardiac biomarkers normalized after dose reduction of levothyroxine.
• Suppressed TSH levels confirmed the iatrogenic thyrotoxicosis.

Implications:

• This case report highlights the potential cardiovascular risks associated with levothyroxine over-replacement.
• Emphasizes the importance of careful dose titration of levothyroxine therapy to avoid iatrogenic hyperthyroidism.
• Suggests measuring TSH levels in patients presenting with acute coronary syndrome and findings consistent with TC.