During his college years, jacob often experienced episodes of intense fear accompanied by the physical sensations of a heart attack. jacob might have experienced a disorder while in college.

I believe the answer is: Panic disorder

The intense fear and general anxiety that a panic disorder patients experience often come without any indications or trigger.
This disorder is usually cuased by prolonged stress in some aspects of the victims' life, such as their  career, their relationships, or their self-confidence.