Critical Cases - New Onset Afib with High Output Heart Failure!


  • 49 yo F  pHx asthma presents  ED with worsening DOE for the last month acutely worsening today 
  • No prior hospitalizations or intubations for asthma exacerbation 


  • Positive for dyspnea, palpitation
  • Positive for abdominal distention, which she attributes to constipation


  • Moderate intermittent asthma on albuterol PRN 

Physical Exam

BP 166/103 HR 173 T 98.8 RR 26 Pox 81% on RA (improved to 97% on 2L NC)

  • Pt awake and alert, conversant
  • HEENT: B/l exophthalmos
  • Pulm: Decreased air movement b/l, rales at bases, no wheezing
  • Heart: tachycardia, irregularly regular rhythm, no murmurs
  • Abd: distended, but no tenderness to palpation
  • Extremities: 2+ pitting edema extending from dorsal feet to proximal shins b/l


ECG Interpretation: Atrial fibrillation with rapid ventricular response with premature ventricular or aberrantly conducted complexes, Rate 174bpm, QTc 507ms


Pulm: No B lines present. Bilateral moderate sized pleural effusions.

CardiacVisibly reduced ejection fraction Normal RV:LV ratio. 

Abbreviated DDx for new onset afib: ”PIRATES”

  • Pulmonary
  • Ischemia
  • Rheumatic
  • Atrial myxoma
  • Thyroid
  • Emboli
  • Sepsis



  • Diltiazem 15mg bolus given with improvement of rate from 260s to 150s
  • Furosemide 40mg IV given
  • Cardiology consult

Clinical Course

  • Patient was weaned from 2 NC to RA 
  • hsTrp <6; proBNP elevated @6,000 
  • Thyroid profile concerning for new dx of hyperthyoidism leading to new onset afib with high output heart failure
  • Thyroid ultrasound demonstrated enlarged heterogeneous hypervascular thyroid gland, consistent with thyroiditis
  • thyrotropin receptor antibodies and thyroid stimulating immunoglobulin resulted at 10.03 (normal < = 2.00) and 379 (normal <140), respectively.

Check out this excellent summary of high output heart failure from the University of Michigan here

  • B blockers should be the mainstay of rate control in patients with afib and thyrotoxicosis (to achieve HR control & decrease peripheral conversion of T4 to T3)
  • PTU or methimazole (PTU preferred as it also decreases peripheral conversion of T4 to T3)
  • In suspected thyroid storm, iodine can be administered >1 hour after PTU/methimazole administration (prevents iodine from being used as a substrate for new hormone synthesis). Check out this awesome summary of the management of thyroid storm here