What is the differential of this very unusual ECG?

Take a look at this ECG first without clinical context:What do you think?There is sinus bradycardia with very unusual shortened QT interval (approximately 400 ms), for a QTc (Bazett) 358 ms. The T-waves have high amplitude and narrow bases, reminiscent of hyperkalemia, maybe also with hypercalcemia. The T-waves are not bulky or fat, and are therefore not hyperacute regardless of their amplitude.Short QTc is rare, but has been described as less than 360 ms for males and less than 370 ms for females. Furthermore, less than 330 ms (males) or less than 340 ms (females) can be termed " very short QTc " and, in the absence of reversible causes, is considered by some to be diagnostic of Short QT Syndrome (SQTS) in an appropriate setting.Now for the clinical context:This was a young man with a gunshot wound to the head, who arrived comatose and critically ill. CT scan showed severe brain injury and cerebral edema.As we have shown on this blog, intracranial hemorrhage can cause various ECG findings, sometimes imitating ischemia, often with bizarre long QT syndromes reminiscent of takotsubo / stress cardiomyopathy. However this is the first time I have seen dramatically shortened QT in this setting. There was no prior for comparison, but this finding would be extremely unlikely to be present on baseline, in the absence of congenital short QT syndrome.The potassium and calcium levels were within normal limits.Learning Points:This ECG in another clinical context should make you consider ...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs