Can the qt interval prolong with anxiety/panic attacks or tachycardia? i thought the qt interval normally shortens during exercise?

No strong data : Although QT lengthening and increased QT dispersion has been described in anxiety states, not aware of a consistent correlation. One difficulty is the effect of concomitant medication use which could be confounding problem. There is clear data indicative of QT shortening with tachycardia. Absence of QT shortening may however be noted with the long QT syndrome.