Ventricular Fibrillation, ICD, LBBB, QRS of 210 ms, Positive Smith Modified Sgarbossa Criteria, and Pacemaker-Mediated Tachycardia

An elderly man collapsed. There was no bystander CPR.  Medics found him in ventricular fibrillation.  He was defibrillated, but they also noticed that he was being internally defibrillated and then found that he had an implantable ICD.He was unidentified and there were no records availableAfter 7 shocks, he was successfully defibrillated and brought to the ED.Bedside ED ultrasound showed exceedingly poor global LV function, and no B lines.Here is the initial ED ECG.  What do you think?Rhythm:  Residents asked me why it is not VT.  If you use calipers (or equvalent), it is clear that the rhythm is irregularly irregular.  So it must be atrial fibrillation.  Then I always look to see if the initial deflection of the QRS has a lot of voltage change per change in time (seen in tachycardias that are initiated from above the ventricle because the propagate through fast conducting purkinje fiber.  In other words, is the initial deflection"steep" [fast depolarization (supraventricular)] or is it not very steep [slow (VT)]?Answer: it is irregularly irregular and the initial part of the QRS is fast, so this is atrial fibrillation with Left Bundle Branch Block (LBBB).QRS: very wide (213 ms)ST-T: The ST-T has a lot of proportionally discordant ST Elevation.  In lead III, the ST/S ratio is 25% (ST measured at the J-point, relative to the PQ junction, is 4.5 mm; the S-wave is 18 mm.  This meets the Smith Modified Sgarbossa criteria for ...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs