P-55 A RARE CAUSE OF TACHYCARDIA IN A POSTPARTUM FEMALE PATIENT WITH HYPOTHYROIDISM: LEFT ATRIAL MYXOMA
Authors: Keskin Müge , Rıza Baykal Gokhan , Kücüker Seref Alp , Özdemir Didem , Aydın Cevdet , Topaloglu Oya , Ersoy Reyhan , Cakır Bekir 
Published: January 2025

Abstract

Introduction
Primary heart tumors are uncommon with cardiac myxoma being the most frequently observed type. This tumor occurs in about 0.03% of the general population, typically appearing sporadically in adults. It can also be inherited as part of the Carney complex. While cardiac myxoma is biologically benign, it behaves functionally as a malignant tumor due to its potential to cause obstruction within the heart, embolization, and various systemic symptoms. Hashimoto's thyroiditis (HT) is a chronic autoimmune condition characterized by lymphocytic inflammation of the thyroid gland.

Clinical Case
A 39-year-old female patient with a diagnosis of primary hypothyroidism visited our outpatient clinic 18 months postpartum. She had palpitations for the past 4 years, which had worsened over the last 2 years and were now severe enough to disturb her sleep. Additionally, she complained of hand tremors when hungry, severe headaches, extreme weakness, and drowsiness after meals. Her medical history included a diagnosis of HT 16 years ago and she was receiving levothyroxine 100 mcg daily. She has lost her mother due to a cerebrovascular event at age 45. On physical examination, her blood pressure was 120/80 mmHg, her heart rate was 88 beats per minute, she had rosacea on her face, and the rest of the examination was normal. Laboratory analysis was as follows: TSH: 1.2mU/L (0.55-4-78), fT3: 3.24ng/L(2.3-4.2), fT4: 1.26ng/dl(0.89-1.76), Hb: 12g/dL(12-15.6), ferritin: 6 microgram/L(10-291), anti thyroglobulin: 269.9IU/mL (&lt;1.3), anti thyroid peroxidase: 389U/mL (&lt;60), glucose: 86mg/dl(70-99). During follow-up, her levothyroxine dose was reduced due to tachycardia, and she was also treated for iron deficiency anemia. Although an echocardiogram was planned to investigate her tachycardia, she did not undergo the procedure. An echocardiogram of the patient revealed an ejection fraction of 60% and a 4.3x3.3cm, well-circumscribed, round shaped mass in the left atrium. This mass, which was attached to the interatrial septum with a stalk and deviated the septum to the right, was consistent with a myxoma and contained areas of calcification. The patient underwent surgery for the left atrial mass, and the pathology results confirmed cardiac myxoma. In evaluations for Carney complex, cortisol was suppresse with the 1 mg dexamethasone suppression test, the glucose-growth hormone (GH) suppression test showed GH levels &lt;0.05 μg/L, and a genetic test could not be performed.

Conclusion
Tachycardia in hypothyroid patients can occur as a side effect of levothyroxine treatment. Additionally, iron deficiency anemia can also lead to sinus tachycardia in these patients. However, if a patient presents with unusual symptoms, such as nocturnal tachycardia, it is crucial to consider the possibility of an underlying cardiac condition. When cardiac myxoma is identified, it is important to evaluate the patient for Carney Complex.