Final answer:
The syncope could be caused by the prolonged QT interval from taking levofloxacin.
Step-by-step explanation:
The syncope (short-lived blackout) experienced by the 63-year-old female while driving could be caused by the prolonged QT interval observed on her ECG. Levofloxacin, the antibiotic she is taking for a urinary tract infection (UTI), can cause QT interval prolongation as a side effect. Prolonged QT intervals can lead to an abnormal heart rhythm called torsades de pointes, which can result in syncope.
It is essential for the patient to inform her physician about the blackout experience as it may warrant further evaluation and consideration of alternative medications.