Racing heart: a case of unrecognized hyperthyroidism presenting as monomorphic ventricular tachycardia
A. Lim & M. Sedurante
Ventricular tachycardia may occur in the setting of primary hyperthyroidism despite the absence of typical hyperthyroid symptoms. The case is a 40-year old female coming in for epigastric pain and vomiting who was incidentally found to have monomorphic ventricular tachycardia. Despite this she was in no respiratory distress, and exhibited no symptoms of heart failure. Other than agitation, physical examination showed no signs of hyperthyroidism. Initial management included numerous electric cardio-versions and Amiodarone, which was immediately discontinued after thyroid function tests revealed a low TSH (<0.005 mIU/l) and elevated free T4 (35 pmol/l) consistent with primary hyperthyroidism. A neck ultrasound revealed normal sized glands and no increased vascularity. Transthoracic echocardiogram showed normal-sized left ventricle with multi-segmental wall motion abnormalities and depressed overall systolic function (EF=49% by Teicholzs). After a few months of treatment with Methimazole 20 mg/day and Propranolol 40 mg/day, free thyroxine levels normalized with no recurrence of ventricular tachycardia. Thyroid scan done 6 months after Amiodarone intake and 1 month off anti-thyroid medications showed normal-sized glands and normal 2/24 h uptake values, and a repeat TTE showed normal geometry and improved ejection fraction at 78%. Patient remains functional on her daily activities and remains asymptomatic.
Conclusion: Ventricular tachycardia as an initial presentation of autoimmune hyperthyroidism is rare, the most common arrhythmia being atrial fibrillation. However treatment with anti thyroid medications, β-blockers and close monitoring can result to improved clinical outcomes.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.