Diagnosic criteria

  Localized PR segment elevation or depression may be observed.

 
Atrial arrhythmias may develop.

  In patients with atrial infarction, Ta wave depression is seen more often than
Ta wave elevation.


References

  Int J Cardiol 2016;202:904-909.

  Journal of Electrocardiology 2011;44:635-640.

  Am J Cardiol 1973;31(4):450-456.





ECG 1. Atrial infarction during acute inferior myocardial infarction. Circumflex coronary artery (Cx) was totally occluded by
thrombus just before giving the left atrial branch. The right coronary artery (RCA) had 70% stenosis.
Localized depression of
PR segment
is observed.

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ECG 2a. The ECG above belongs to a 73 years-old man with coronary artery disease, old myocardial infarction,
mild left ventricular systolic dysfunction and chronic renal failure. Several coronary stents had been implanted in the past.
ECHOcardiography did not show pericardial effusion.
He does not have chest pain or dyspnea at the moment.
He also does not have clinical or laboratory evidence of acute pericarditis.
PR depression is seen in right precordial leads.
The above ECG was recorded at a
standard calibration of 10 mm/mV.

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ECG 2b. The ECG above was recorded immediately before the ECG 2a.
It was recorded at a
calibration of 20 mm/mV to depict PR depression (Ta depression) clearly.
The
initial part of the P wave is positive and the terminal part of the P wave is negative in precordial leads.
However, the terminal negativity of the P wave is not solely responsible for the observed PR depression.
The PR segment after termination of the P wave is still depressed. This finding suggests that the patient had
infarction of atrial myocardium in the past.

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ECG 2c. Above is a zoomed view from a section of the ECG 2b showing
PR depression (Ta depression) clearly.