I have read conflicting articles on prolonged qt and sertraline. does it cause a prolonged qt? also can xanax (alprazolam) xr?

Sertraline yes: Xanax (alprazolam) no. All SSRI/SNRI antidepressants have been associated with prolonged QTc intervals, but it is usually dose related, and rarely occurs at lower ends of the dosage range in most people. If there is a history of prolonged QTc syndrome in your family, or you have had symptoms (palpitations, dizziness, fainting, lightheadedness, unexplained seizures), have ECG monitored. No reports with Xanax (alprazolam).