ECG Case 099

ECG from a 19 yr old referred by their GP for investigation of palpitations found at a routine medical review. The patient is asymptomatic with no past medical history or regular medications.

ECG Case 099 LITFL Top 100 EKG

Describe and interpret this ECG



  • Mean ventricular rate 60 bpm


  • Complicated and difficult to fully ascertain on a single ECG
  • Atrial activity seen
    • P waves clearly visible
    • Variable P-P interval 
    • Apparent drop of P waves before 2nd, 3rd, and 4th ventricular ectopics
    • I think the P waves are actually buried in the initial portion of the wide QRS best appreciated in the 4th ventricular ectopic (green circle) rather than representing SA exit block.
ECG Case 099b LITFL Top 100 EKG
  • Evidence of AV block
    • Multiple non-conducted P waves
    • No progressive PR prolongation evident – longer rhythm strip would be helpful
    • 2nd Degree AV Block Mobitz II
  • Frequent PVC’s
    • 4 During 10 second recording
    • Likely unifocal
    • 1st PVC likely has some fusion due to proximity to preceding P wave

Axis (Conducted QRS):

  • Normal

Intervals (Conducted QRS):

  • PR – Prolonged (220ms)
  • QRS – Normal
  • QT – 340ms


The ECG in Athlete’s

There are a number of adaptive physiological changes seen in athlete’s as a response to regular exercise including cardiac changes such as change in LV wall thickness or end-diastolic LV volume (Lisman KA). These physiological adaptations can also be manifest as changes on the 12-lead ECG.

The challenge for clinicians is picking those changes that require further investigation for potential causes of sudden cardiac death versus those that represent normal adaptation.Thankfully there is an Consensus International Criteria for ECG Interpretation in Athletes, aka ‘Seattle criteria’, developed in 2015 with the latest version published in BJSM in 2017.

It provides guidance on those ECG features that can be considered a normal response to exercise, those that are ‘borderline’ and those that require further investigation. The updated version also provided guidance on differentials associated with each ECG abnormality and appropriate investigation modalities. The following flow chart summaries these groups of ECG findings:

International criteria for electrocardiographic interpretation in athletes:
Drezner JA, Sharma S, Baggish A, et al. International criteria for electrocardiographic interpretation in athletes: Consensus statement. Br J Sports Med 2017;51:704-731


In Our Case

The abnormal findings seen on this ECG:

  • Frequent PVC’s – 4 seen in 10 second window equating to up to ~35000/day 
  • Mobitz II AV Block

Differential causes for these features include:

Refer patient for further cardiac investigation which may include echo, 24-holter, ILR, EP study and cardiac MRI


TOP 100 ECG Series

Emergency Medicine Specialist MBChB FRCEM FACEM. Medical Education, Cardiology and Web Based Resources | @jjlarkin78 | LinkedIn |


  1. I think there are definite Wenckebach periods (beats 4, 5 and 7, 8, each followed by a nonconducted P). There are escape beats (2, 3 for example) that I would guess are juctional in origin. Beat 2 is preceded by a P but with a short PR. The escape beat got to the ventricle first.

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