Case Presentation: A 37-year-old-male with no significant past medical history who presents to the hospital with 2 months of progressive exertional dyspnea, palpitations and scrotal pain. He has also noticed some leg swelling and has a nonproductive cough. For the past 6 months, he has had ongoing diarrhea and unintentional weight loss of about 20 lbs. He denies fevers, chills, chest pain, hemoptysis, abdominal pain. He takes no medications at home and used to be able to workout daily up until 2 months ago due to dyspnea. He denies recent travel or sick contacts. His vitals on presentation are notable for heart rate of 130, BP 128/80, RR 24, oxygen saturation of 95% on room air. Physical exam reveals a thin, otherwise well-developed male with mild tachypnea, tachycardia with irregular heart rhythm, crackles at bilateral lung bases, 1+ pitting edema in the lower extremities extending up to the groin bilaterally, intact mental status. His workup is notable for EKG showing atrial fibrillation without ST-T changes. Chest x-ray shows pulmonary congestion with mild bilateral pleural effusions. Echocardiogram shows diffuse hypokinetic wall motion with decreased LVEF of 35-40%. Labs are notable for TSH<0.01 µIU/mL, free T4 of 6.4 ng/dL. Patient receives 20mg IV Lasix and endocrine is consulted for management of thyroid storm. Patient is monitored on telemetry and decision is made not to call ICU because of his relatively stable vitals and clinical exam. Per endocrine recommendation, patient is given 1mg of IV propranolol followed by 40mg of PO propranolol 1 hour later. About 1 hour after receiving PO propranolol, patient’s heart rate on the telemetry monitoring rapidly decreases from about 110-120 beats per minute down to 30 beats per minute and he goes into cardiopulmonary arrest (PEA). ACLS protocol is initiated immediately and patient has return of spontaneous circulation within 5 minutes. He is intubated and transferred to the ICU.

Discussion: Propranolol has been traditionally used to treat thyrotoxicosis and thyroid storm due to its added benefit of blocking peripheral conversion of T4 to T3; however, recent literature is suggesting that because of the long elimination half life of propranolol (2-6 hours), it is no longer recommended in patients with heart failure with reduced ejection fraction because the risk of worsening heart failure and cardiac arrest. Instead, short acting beta blockers are recommended such as esmolol or landiolol because of their short elimination half life (about 9 and 4 minutes, respectively).

Conclusions: Patients who present with thyroid storm have risk of mortality from 10-30%. Those who present with severe heart failure are at increased risk of cardiopulmonary arrest with beta blockade because they may be dependent on the hyperadrenergic state to maintain cardiac output and sudden beta blockade can lead to inability to compensate and cause hemodynamic collapse. Short acting beta blockers such as esmolol or landiolol have more cardioselectivity and allow for safer and more rapid dose titration to prevent hemodynamic instability.