A 54 year old male with no past history presents with one hour of chest pain. He is anxious and diaphoretic.
His BP is 100/60 supine, respiratory rate is 28/min and sats are 99% on 10L/min of O2.
Here is his ECG.
Using the ECG in 20 Seconds Method
Rate: (25 x6) = 150
Rhythm: There are some P waves but not many. The QRS’s are irregularly irregular, so this is atrial fibrillation.
QRS: Normal width, not too tall, not too small and normal morphology.
ST-T: With chest pain we look for ischaemic changes in the arterial territories.
-anterior: There is ST depression in V2 and V3
-Lateral: There is ST depression in I, aVL and V5 and some ST elevation in V6
-Inferior: ST elevation in II, III and aVF
This is atrial fibrillation with an inferior ST elevation acute myocardial infarction, with reciprocal changes in lateral and anterior leads. Due to the ST depression pattern we need to perform posterior leads. Also, a right ventricular ECG is needed as 30% of inferior infarcts have a right ventricular involvement.
Beware as 5% of inferior infarction is secondary to aortic dissection, so at a minimum a chest Xray is needed and it would be beneficial to use the ultrasound machine to perform a quick cardiac ultrasound looking especially for a pericardial effusion.
If this is a pure MI, this patient needs cath lab or lytics.
Here is a question. Given that the patient is somewhat unstable and given he is in atrial fibrillation, do we cardiovert?
What is the atrial fibrillation due to? The usual causes are atrial ischaemia, atrial distension with left ventricular failure(which may be the case here, given the respiratory rate and the reduced saturations) or significant diastolic left ventricular dysfunction.
If purely an inferior infarction, there will be right coronary artery ischaemia. If there is posterior involvement, there may also be circumflex involvement.
The best management is to remove the thrombus. The atrial fibrillation may be transient.