For more on Terminal QRS distortion, see these posts:

Best Explanation of Terminal QRS Distortion in Diagnosis of Electrocardiographically Subtle LAD Occlusion

4 Cases Discussing Terminal QRS Distortion in Diagnosis of Anterior MI

The paramedic crew of Rick Morton and Kim Baker, of Ambulance Victoria in Australia, took care of this patient.  Their friend Shane Chapman sent the case to me.  He asked some questions which I put and answer at the bottom.

Case

A 60 something year old gentleman presented with chest pain radiating into left arm and a recent hx of SOB on exertion and fatigue for past 2 days.

Here are the ECGs and the times of their recording:

1529 This shows very high ST Elevation.  There are well formed S-waves in V2 and V3.  The S-wave in V4 is beginning to disappear. At 1544, the S-wave in V3 is much small, has almost disappeared. The S-wave in V4 has completely disappeared. A Q-wave is developing in V3 Prehospital Thrombolytics were appropriately given at 1600. Good work, guys!!! At 1620, the S-wave in V3 is almost completely gone.

More ECGs were recorded:

At 1655, there is even less S-wave in V3 Note: this never quite meets the criteria for terminal QRS distortion (TQRSD), which is zero S-wave or J-wave in either of V2 or V3. These criteria have importance in our study of 171 cases of normal variant ST elevation (early repolarization), not one case had TQRSD by this definition. Terminal QRS distortion is present in anterior myocardial infarction but absent in early repolarization . At 1656, there is now Left Bundle Branch Block.  The heart rate has increased, so it is unclear if this change is due to rate dependent LBBB, or if it is due to ischemia of the left bundle branch. There appear to be hyperacute T-waves in II, III, and aVF.  Is there also an inferior MI (wraparound LAD to inferior wall? –this was one question they asked.) Notice we can’t calculate the modified Sgarbossa ratio because the S-wave is cut off. 1659 Reperfusing!! LBBB is resolved Notice that the ST elevation is receding (but rate is a bit slower) Notice that the S-waves are re-constituting

1716

Some persistent ST elevation, and persistent Q-wave in V3 and V4. Successful reperfusion by thrombolytic therapy.

Now pain free, this ECG was recorded on arrival to the ED:

All ST Elevation is gone.  No Q-wave in V3 (these may indeed disappear with reperfusion)

Cath results:

Spontaneous coronary artery dissection (SCAD) of the mid LAD. 

No stent just managed medically and discharged home and doing well.

Could I please ask for your expert opinion?

Is this a wrap around STEMI?

        It has some features — hyperacute T-waves appear to develop in II, III, aVF at 1656.

Can you explain the normal R-wave progression through the precordial leads? 

        This can be normal in anterior STEMI

Can you have normal R wave progression in the setting of STEMI?  

        Yes, you can.