I can only speak from my perspective, I am a 4th year medical student and will be angling for internal medicine to hopefully a cardiology fellowship after residency.
If I had to do it all over again I have to admit I wouldn't, Med school is miserable as hell, licensing exams are never ending, debt is insane, and the amount of schooling required before you see a real paycheck is ridiculous (hint residency and fellowship don't pay much), Here is what you have to look forward to if you go for cardiology:
Bachelors degree - 4 years
Medical school - 4 years
Residency - 3 years (through internal medicine)
Cardiology fellowship - 3 years + 1 year if you want invasive
Total: 14 years excluding a masters degree I if you don't get in right away, I had to get one and it was a further drain of cash and time.
Now on to competitiveness, you need to study until your eyes bleed and do well on standardized tests, as no admissions committee will look twice for bad grades or licensing exams.
You will need to do good on the MCAT, job shadow doctors, do volunteer work, get a high undergrad gpa and then pass an often challenging Med school interview
Now once your in med school you'll have to pass your classes and take USMLE step1, 2ck, 2cs, 3 + licensing exams to become board certified, each exam is about 9 hours and super stressful, if you do bad on any of these bad boys your odds of getting a residency go down the drain and you will be in serious trouble, like you might graduate med school with you MD degree but you won't have a job since you didn't get a residency, there are not enough residencies for every Med school graduate, it happens. To make matters worse cardio is ultra competitive so you may not match after your residency.
Basically what I am saying is you need to really commit, the cost is monumental so once you have accrued your first 50k of debt its really too late to turn back.
Btw did I mention that during residency you work crazy hours? Eh you get the idea.
This post was edited by dogboston on Aug 14 2016 11:10pm