New RBBB and subtle NSTEMI

This 49 year old male presented with chest pain.

Initial ECG: sinus with QRS of 128 ms and RBBB, though not obvious.  There is T-wave inversion in lead III and a very large T-wave in aVL (very large only compared to the small size of the QRS, and it is proportional ST elevation and T-wave size that is important, not absolute size!)  One would predict high lateral MI from this ECG.

ECG from one year ago (baseline), with QRS of 105 ms.  This confirms that the RBBB and the ST-T findings in III and aVL are new.

His chest pain resolved, then recurred, and the following ECG was recorded 70 minutes after presentation:

ECG at t=70 minutes, showing dynamic T-waves (new T-wave inversion in II and deepening T inversion in III and aVF, and increasing ST depression in III, as well as increasing hyperacute T in aVL

His chest pain resolved again, he was started on heparin, and was admitted pain free.  Initial troponin I's were 0.25 and 0.46 ng/ml.

At midnight the patient was still pain free and another ECG was recorded:

ECG at t = 8 hours, minimally changed

At cath the next day, the culprit was a 99% proximal RCA with good flow.  There was a posterolateral (RPL-1) branch off of this RCA with a 90% stenosis.

I have changed the outcome of this case because there is uncertainty as to whether, angiographically, there was ischemia to the inferior (RCA) or the lateral wall (RPL-1). My assessment from the ECG is that it was high lateral, with reciprocal inferior ST findings.  But the angiographer thinks that it was the inferior wall that was most ischemic.