typical ECG findings associated with hypercalcemia: short QT (e.g. QTc < 400 msec), ST-segment depression
typical ECG findings associated with hypocalcemia: prolonged QT
note that hyperkalemia is often associated with hypocalcemia, and as a result hyperkalemic patients often have a prolonged QT, but it's not the hyperkalemia that prolongs the QT, it's the hypocalcemia
