It will depend on why the QT is prolonged. Be sure the cardiologist dictates a report that contains the items listed in this link
http://www.faa.gov/about/office_org/...ardiovascular/ as well as any other tests he deems appropriate.
Again, medications may be approved or disapproved depending on the reason they are prescribed. Just because a drug like atenolol is approved for hypertension does not mean it may be approved for a cardiac rhythm abnormaility.