SESSION TITLE: Autoimmune Disorders: Both Primary and SecondarySESSION TYPE: Rapid Fire Case ReportsPRESENTED ON: 10/18/2022 10:15 am - 11:10 amINTRODUCTION: Hypothyroidism affects 5% of people worldwide (1). Untreated and under-treated hypothyroidism is associated with cardiovascular disease and increased mortality. Pericardial effusion is a rare and serious complication of hypothyroidism, but the development of life-threatening cardiac tamponade is even less reported.CASE PRESENTATION: A 68-year-old male with a history of myasthenia gravis and hypothyroidism due to radioactive iodine ablation for management of Graves’s disease presented to the hospital with worsening dyspnea for one month. He reported non-adherence to levothyroxine for two years due to financial issues. Vitals signs included regular heart rate of 54 beats/minute, blood pressure of 130/60 mmHg, respiratory rate of 18 breaths/minute, and saturation of 93% on 2 L of oxygen via nasal cannula. Examination revealed diminished heart sounds, and bilaterally clear breath sounds. Based on the clinical presentation, computerized tomography of the chest with intravenous contrast was ordered and revealed large pericardial effusion. An electrocardiogram (EKG) showed sinus bradycardia and low voltage QRS complexes. Transthoracic echocardiogram revealed a large pericardial effusion and right atrial collapse with signs of tamponade physiology. Immediate ultrasound-guided pericardiocentesis was performed and removed 1 L of serosanguinous fluid with a resolution of cardiac tamponade. Autoimmune, infectious, and malignant processes were excluded by testing pericardial fluid, however, blood sample revealed elevated thyroid-stimulating hormone (TSH) of 88.3 mcIU/mL and T4 level of 0.52 ng/dl, suggesting hypothyroidism as a cause of tamponade.DISCUSSION: The clinical triad of hypotension, distant heart sounds, and jugular vein engorgement is a hallmark of cardiac tamponade known as Beck’s triad which may be present or absent in tamponade related to hypothyroidism (2). High thyroid-stimulating hormone level, relative bradycardia, and low QRS voltage in the EKG are clinical manifestations of pericardial effusion in hypothyroidism and associated with subtle onset without initial significant hemodynamic changes. General discordance between the volume of effusion and clinical symptoms can create a diagnostic challenge. The sequence of events is from moderate to large pericardial effusion without tamponade, followed by echocardiographic tamponade without a paradoxical pulse. Hemodynamic collapse occurs when pericardial pressure exceeds intracavitary pressure (3). Compared to the prevalence of other causes of cardiac tamponade, hypothyroidism is rarely observed and can be overlooked as one of the differential diagnoses.CONCLUSIONS: This case illustrates the importance of measuring thyroid-stimulating hormone and considering hypothyroidism as a potential cause of cardiac tamponade. Compliance with levothyroxine plays a crucial role in preventing and managing pericardial effusion in hypothyroidism.Reference #1: Udovcic M, Pena RH, Patham B, Tabatabai L, Kansara A. Hypothyroidism and the Heart. Methodist Debakey Cardiovasc J. 2017;13(2):55–9.Reference #2: Chahine J, Ala CK, Gentry JL, Pantalone KM, Klein AL. Pericardial diseases in patients with hypothyroidism. Heart. 2019 Jul 1;105(13):1027–33.Reference #3: Sinha A, Yeruva SLH, Kumar R, Curry BH. Early Cardiac Tamponade in a Patient with Postsurgical Hypothyroidism. Case Rep Cardiol. 2015;2015: 310350.DISCLOSURES: No relevant relationships by Nemanja DraguljevicNo relevant relationships by Kristina MenchacaNo relevant relationships by Catherine Ostos Perez SESSION TITLE: Autoimmune Disorders: Both Primary and Secondary SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/18/2022 10:15 am - 11:10 am INTRODUCTION: Hypothyroidism affects 5% of people worldwide (1). Untreated and under-treated hypothyroidism is associated with cardiovascular disease and increased mortality. Pericardial effusion is a rare and serious complication of hypothyroidism, but the development of life-threatening cardiac tamponade is even less reported. CASE PRESENTATION: A 68-year-old male with a history of myasthenia gravis and hypothyroidism due to radioactive iodine ablation for management of Graves’s disease presented to the hospital with worsening dyspnea for one month. He reported non-adherence to levothyroxine for two years due to financial issues. Vitals signs included regular heart rate of 54 beats/minute, blood pressure of 130/60 mmHg, respiratory rate of 18 breaths/minute, and saturation of 93% on 2 L of oxygen via nasal cannula. Examination revealed diminished heart sounds, and bilaterally clear breath sounds. Based on the clinical presentation, computerized tomography of the chest with intravenous contrast was ordered and revealed large pericardial effusion. An electrocardiogram (EKG) showed sinus bradycardia and low voltage QRS complexes. Transthoracic echocardiogram revealed a large pericardial effusion and right atrial collapse with signs of tamponade physiology. Immediate ultrasound-guided pericardiocentesis was performed and removed 1 L of serosanguinous fluid with a resolution of cardiac tamponade. Autoimmune, infectious, and malignant processes were excluded by testing pericardial fluid, however, blood sample revealed elevated thyroid-stimulating hormone (TSH) of 88.3 mcIU/mL and T4 level of 0.52 ng/dl, suggesting hypothyroidism as a cause of tamponade. DISCUSSION: The clinical triad of hypotension, distant heart sounds, and jugular vein engorgement is a hallmark of cardiac tamponade known as Beck’s triad which may be present or absent in tamponade related to hypothyroidism (2). High thyroid-stimulating hormone level, relative bradycardia, and low QRS voltage in the EKG are clinical manifestations of pericardial effusion in hypothyroidism and associated with subtle onset without initial significant hemodynamic changes. General discordance between the volume of effusion and clinical symptoms can create a diagnostic challenge. The sequence of events is from moderate to large pericardial effusion without tamponade, followed by echocardiographic tamponade without a paradoxical pulse. Hemodynamic collapse occurs when pericardial pressure exceeds intracavitary pressure (3). Compared to the prevalence of other causes of cardiac tamponade, hypothyroidism is rarely observed and can be overlooked as one of the differential diagnoses. CONCLUSIONS: This case illustrates the importance of measuring thyroid-stimulating hormone and considering hypothyroidism as a potential cause of cardiac tamponade. Compliance with levothyroxine plays a crucial role in preventing and managing pericardial effusion in hypothyroidism. Reference #1: Udovcic M, Pena RH, Patham B, Tabatabai L, Kansara A. Hypothyroidism and the Heart. Methodist Debakey Cardiovasc J. 2017;13(2):55–9. Reference #2: Chahine J, Ala CK, Gentry JL, Pantalone KM, Klein AL. Pericardial diseases in patients with hypothyroidism. Heart. 2019 Jul 1;105(13):1027–33. Reference #3: Sinha A, Yeruva SLH, Kumar R, Curry BH. Early Cardiac Tamponade in a Patient with Postsurgical Hypothyroidism. Case Rep Cardiol. 2015;2015: 310350. DISCLOSURES: No relevant relationships by Nemanja Draguljevic No relevant relationships by Kristina Menchaca No relevant relationships by Catherine Ostos Perez