That's really a great case. Life-saving!

Possible differentials for prominent U-wave:

1. Electrolyte abnormalities (HYPOS: hypokalemia, hypomagnesemia and hypocalcemia).
2. Anti-arrhythmic medications: for example sotalol
3. Left ventricular hypertrophy.
4. Sometimes we see negative or inverted U-waves with myocardial ischemia.

What is the definition of prominent U-wave?

Should we always count U-wave as part of QT prolongation and hence the increased risk of subsequent Torsade De Pointes