Shark fin post arrest: do you understand the ECG?

Case submitted by Dr. Daryl Williams, written by Pendell Meyers, peer reviewed by Smith and BraceyA physician bystander witnessed a middle-aged or slightly elderly man suddenly collapse while walking down the street, very close to the hospital. The physician immediately started CPR and called EMS. EMS arrived quickly and found the patient to be in VFib. After several shocks the patient achieved ROSC.A minute or so after arrival to the ED, he went back into VFib and was immediately shocked back out into sinus rhythm.His EMS ECG during initial ROSC was available for the ED team:Here is his ED ECG:What do you think?Both ECGs above show RBBB + LAFB, with massive concordant STE in leads V2-V6 as well as I and aVL. There is shark fin morphology (aka " Giant R wave " , or " Lambda wave " ), in which the wide complex QRS appears to fuse with the massive STE, causing confusion as to where the J point actually is, and where the QRS ends and the ST segment begins. This pattern is diagnostic of at least LAD occlusion (which of course supplies the anterolateral walls and the RBB and LAF), but given how severe the findings are even out into the high lateral wall, the occlusion may even be more proximal, such as the left main. This pattern is more commonly seen in LAD occlusion simply because persistent left main occlusion is rare, probably because it such patients rarely survive long enough to obtain an ECG and/or angiogram.Below, I have placed red vertical lines at the J points.I was...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs