EMConference: Scary EKG Findings & Syncope

Initial Approach: 

Is there an obvious tachyarrhythmia or bradyarrhythmia? 

  • Look for SVT, AFib RVR, non-sustained VT 

  • Look for sinus bradycardia or sinus pauses >3 seconds 

  • may be associated with failing implanted pacemaker 

  • Look for heart block 

  • Syncope usually associated with Mobitz II or 3rd degree heart block 

 If any of the above are present, treat the root cause with antiarrhythmics, cardioversion, and/or pacing dependent on the arrhythmia 

 Digging Deeper: 

Without obvious tachycardia or bradycardia, look for further signs on the EKG of less common causes of syncope 

Arrhythmogenic right ventricular dysplasia: 

  • T wave inversions in V1-V3, epsilon waves, RBBB, QRS widening in V1-V3 


  • RBBB, Coved ST elevations in V1-V3 (Brugada sign) 

Left ventricular hypertrophy: 

  • Cornell criteria – R wave in aVL plus S wave in V3. LVH if over 28 in males or 20 in females 

  • Asymmetric T wave inversion in V5/V6. Can have ST elevations in V1-V3 

  • If caused by HOCM, can have needle-like q waves 

QT prolongation/Shortening 

  • QT >450 or 500ms (usually drug-caused or genetic) 

  • QT <350ms (usually genetic ion channel dysfunction) 

Pulmonary Embolism 

  • Look for right heart strain: Sinus tachycardia, right axis, deep symmetrical T wave inversions in precordial leads, new RBBB, S1Q3T3 


  • Short PR interval, delta wave 



  • Thiruganasambandamoorthy, Venkatesh, and James Quinn. "Syncope." Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9e Eds. Judith E. Tintinalli, et al. McGraw Hill, 2020