Falsely prolonged QT interval may be a feature of which one of the following conditions?

Hypokalemia (plasma K+ ~ 3.5 mEq/L) causes a widened concentration gradient for K+ (inside & outside). This results in altered repolarization of ventricles and there would be prominent U wave now, which will immediately follow the T wave. The actual QT interval remains normal (~ 0.4 sec); however, the U wave is erroneously considered a pa of the T wave, and a falsely prolonged QT interval of 0.6 sec is measured.