a 36-year-old woman presents to the ed with sudden onset of left-sided chest pain and mild shortness of breath that began the night before. she was able to fall asleep without difficulty but woke up in the morning with persistent pain that is worsened upon taking a deep breath. she walked up the stairs at home and became very short of breath, which made her come to the ed. two weeks ago, she took a 7-hour flight from europe and since then has left-sided calf pain and swelling. what is the most common ecg finding for this patient's presentation?