First of all you have to get entry into a medical school

First, undergrad doesn’t matter. Don’t fail organic chemistry and don’t fail cell biology. Biochemistry is important. Start studying for the MCAT AT LEAST six months before. Make time to take it more than once. Have good letters of rec and make sure you are well rounded. Start your volunteer hours now. Cardiac surgery is one of the hardest and longest paths, just because of the residency and fellowships necessary. Don’t go to shitty medical school, but don’t need to go to the best. It doesn’t matter if you’re a DO or an MD. Always make time for yourself and sleep. Feel free to take a gap year after undergrad. Get a CNA and work in a hospital PRN as soon as you are 18. Work and SAVE MONEY. School is the first priority. People don’t matter if they aren’t there to help you get better. Make relationships with your professors. Nothing you learn in undergrad really matters. You will need to do a general residency surgery at the best place you can and perform well. Try to be chief resident. Then apply to fellowships for cardio. It could take years of applying to med school and residencies and fellowships. Don’t give up.