Atrial MI

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This is part of: Myocardial Infarction

In approximately 10% of infarctpatients, atrial infarct is suspected. An atrial infarct can manifest itself in atrial rhytmdisturbances: atrial fibrillation / atrial rhythm. Because the atria are hemodynamically of minor importance, the consequences of an atrial infarct are limited (and therfore often missed!).

On the ECG, an atrial infarct manifests by rhythm changes and/or change of the P-Ta segment (sometimes called PTA (P - atriale T) segment or PR or PQ or PTp (P - T wave of P wave) segment)[1]. This is the part between the end of the P wave and the Q. The ST segment indicates an infarct in the ventricle, the P-Ta segment indicates an infarct in the atria.

Diagnostic criteria for an atrial infarct [2]:

  • P-Ta elevation >0.5mm in V5 and V6 with reciprocal depression in V1 and V2
  • P-Ta elevation >0.5mm in I and depression in II and III
  • > 1.5mm P-Ta depression in precordial leads
  • > 1.2mm P-Ta depression in I,II or III in combination with atrial arrhytmias

Several diagnostic criteria are in use, and this is just an example of one. An important differential diagnosis of PTa segment elevation or depression is pericarditis.


  1. ABILDSKOV JA. The atrial complex of the electrocardiogram. Am Heart J. 1959 Jun;57(6):930-41. DOI:10.1016/0002-8703(59)90303-5 | PubMed ID:13649561 | HubMed [Abildskov]
  2. LIU CK, GREENSPAN G, and PICCIRILLO RT. Atrial infarction of the heart. Circulation. 1961 Mar;23:331-8. DOI:10.1161/01.cir.23.3.331 | PubMed ID:13762787 | HubMed [Liu]

All Medline abstracts: PubMed | HubMed