Are the subjects of an interventional cardiologist hard in college and university? thank you.

Not really: An interventional cardiologist has undergone 11 or 12 years of training past college/university (4 med school, 3 im residency, 3 cardiology, and 1-2 interventional years). There are an infinite number of paths into med school from music majors to engineering to genetics. While i recommend a science background, many arts majors do very well once in med school.

Same asAny Physician: Difficulty is in the eye of the beholder. The crucial determinant of success is putting in the time to the exclusion of many other activities one might want to do through college, med school & another ~6 years after that. Be aware that interventional cardiology is often about partially salvaging disasters others have allowed to progress for decades, expect "fixed" quickly & yet may not appreciate.