A 55 year old female patient attends her general practice for an appointment with you. She tells you that she experienced two episodes of severe chest pain last night, which lasted for about 2 minutes each. At the time she was watching a scary movie with her husband, which she does not normally do. She tells you that the pain went away and has not came back. She has never experienced anything like it before and is worried she experienced a heart attack. She denies any FAST symptoms or having eaten anything two hours before the pain. What is the most likely diagnosis?