Acute posterior wall myocardial infarction with inferior wall myocardial infaction

A 59-years-male came with history of acute onset retrosternal chest pain of 2 hours duration. He was a chronic smoker and known case of diabetes mellitus since last 6 years and was on oral hypoglycemic agent for the same. Patient was also complaining of dyspnea, orthopnoea and paroxysmal nocturnal dyspnoea. Patient went to local hospital, ECG was done, which was suggestive of ST elevation myocardial infarction. Patient was immediately thrombolysed with tenecteplase. Patient was intubated, kept on ventilator in view of acute congestive heart failure and left ventricular dysfunction and referred to our hospital . During evaluation in emergency patient pulse was 100 beats per minute, Blood pressure 80/60 mmhg, on respiratory system examination bilateral crepitations were present.

First ECG of the patient 

ECG  of the patient is showing heart rate of 125 beats per minute, narrow QRS complex, PR interval 160 msec duration, there is ST segment elevation in lead II,III,avF. Also there is marked ST segment depression with ST segment flattening in lead V1,V2, V3. T wave in lead V1-V3 are all and upright, Tall and broad R wave in lead V1,V2, R wave in lead V1,V2 of 40 msec ( one small square), R/S ratio in lead V2 is equal to 1 (R wave height is 6 small square, and S wave depth is also 6 small square) so ecg is suggestive of posterior wall myocardial infarction.

ECG done after 5 minute

ECG is showing ST segment elevation in lead II,III, avF. There is marked ST segment depression in lead V1-V3 so the diagnosis of this patient is inferior wall myocardial infarction with posterior wall myocardial infarction.

Patient posterior lead ECG could not be done as patient was on ventilator. Patient was thrombolysed.

 

Post Thrombolysis ECG of the patient

ECG is showing normal sinus rhythm at 100 beats per min, normal axis, there is small Q wave seen in lead II,III,avF. Also mild ST segment elevation or upward convexity seen in lead II,III. There are tall T wave seen in lead V2. so ECG is suggestive of successful thrombolysis as there is ST segment resolution in the ECG.

So the final diagnosis is ST elevation posterior wall myocardial infarction with inferior wall myocardial infarction with successful thrombolysis.

Little about ECG finding in 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.