CardioNerds ECG Challenge #7

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53 yo Italian F with COPD after eating too much ribollita​

What accounts for the ST segment abnormalities seen in 2, 3 and aVF


Atrial repolarization (Ta wave) from right atrial enlargement accounts for these repolarization changes in 2, 3 and aVF. ​

Learning Points

The P wave axis is 75⁰, rightward shifted and at the upper limit to be called sinus.  The heart rate is 94.  The peaked P waves in leads 2, 3 and aVF all exceed 3 mm in height and the P waves in V1 and V2 are entirely upright and exceed 1.5 mm.  In leads 2, 3 and aVF, where the P waves are largest, atrial repolarization is evident as a negative deflection (Ta wave) in the respective ST segment of 2, 3 and aVF (see blue arrows).  These ST segment abnormalities are due to right atrial enlargement and are not ST segment abnormalities of ventricular origin (1,2).​

Show Answer

Powered by EKGaction: EKGaction is much more than the usual textbook of EKG and is different from other online programs.  It teaches/reinforces EKG interpretation skills using a method that integrates clinical pearls that makes it easier to commit to memory.  These pearls accompany every case and are called Learning Points and Collateral Tracings.  The multiple indexes make it useful as a reference. It has been perfected over 15 years, teaching at leading cardiology fellowship programs.  It has been shown to improve performance on board exams and it’s fun to use!

Learn more at

1. Surawicz B and TK Knilans. Chou’s Electrocardiography in Clinical Practice, 6th Edition. 2008; Philadelphia. Saunders Elsevier. Pp 42-3 and 240. Addresses how this ST change​
can give spurious results for inferior wall ischemia.​
2. Schiavone W. 2019; Supplemental case 86 for Ta wave (LAE) and Supplemental case 87 for Ta wave (RAE).​