If you are in your 12th, you should have Physics, Chemistry, Biology and English as your core subjects. You should score a minimum of 50% in Physics, Chemistry and Biology. It is 50% for General Category, 45% for PWD and 40% for OBC,SC,ST. Now this aggregate in your 12th is important for you to be eligible for appearing for NEET exam. NEET is the entrance exam for admission to Medical, Dental, Ayush and Veterinary courses across India. To appear for NEET, you should be 17 years atleast by December 31st of the year of taking admission to Medical College. Once you get a seat and join MBBS, it is a 50 month course and 1year mandatory rotational internship. Post this you will have to qualify in NEXT for taking up Cardiology as a specialisation in your PG. For now, the entrance exam for PG courses is NEET PG but it will be replaced by NEXT in the next 3 years.