Posterior wall myocardial infarction with inferior wall myocardial infarction

A 45 years old male came with the history of acute onset retrosternal chest pain of 3 hours duration. The patient was a chronic smoker. ECG is shown below

ECG 1

ECG is showing bradycardia with heart rate of 38 beats per minute, regular in nature, no clearly visible P wave seen, there is ST segment elevation in lead 2,3,avF with marked ST-segment depression in lead V1-V5, also in lead V6, there is prominent R wave seen in lead V2, V3 along with upright T wave seen in lead V2-V5.  ECG is suggestive of acute inferior wall myocardial infarction with posterior wall myocardial infarction with junctional bradycardia.

ECG 2

ECG is showing ST-segment elevation in lead 2,3,avF with marked ST-segment depression in lead V1-V4 also in lead V5, there is prominent R wave seen in lead V1- V4 suggestive of R/S ratio > 1 along with upright T wave in lead V2-V6, suggestive of posterior wall myocardial infarction. 

The patient was immediately started on streptokinase thrombolytic therapy. Post thrombolysis ECG is shown below.

 ECG 3 (Post thrombolysis)

 ECG after thrombolysis was still showing ST-segment elevation in lead 2,3,avF with ST-segment depression in lead V1-V5 suggestive of failed thrombolysis. The patient was immediately taken for Rescue PCI which was suggestive of Co-dominant coronary circulation with both RCA and LCX dominance with TIMI 3 flow so further intervention was deferred. The patient was started on medical therapy and planned for delayed Percutaneous intervention.

Little bit about Posterior wall myocardial infarction

Posterior wall myocardial infarction (MI) occur due to occlusion of either the left circumflex or the right coronary artery. It most commonly occur with acute inferior or lateral MI; but isolated posterior wall MI can occur. 

Electrocardiographic abnormalities suggestive of acute posterior wall MI include  (in leads V1, V2, or V3): 

(1) Horizontal ST segment depression

(2) Tall, upright T wave;

 (3) Tall, wide R wave

 (4) R/S wave ratio greater than 1.0 (in lead V2 only). 

Combination of horizontal ST segment depression with an upright T wave increased the diagnostic accuracy of these two separate electrocardiographic findings. 

The additional-lead electrocardiogram using left posterior thorax leads is potentially helpful; ST segment elevation greater than 1 mm in this distribution suggests an acute posterior wall MI

Reference
Brady WJ. Acute posterior wall myocardial infarction: electrocardiographic manifestations. The American journal of emergency medicine. 1998 Jul 1;16(4):409-13.
Thank you
Praveen Gupta