You cannot directly pursue an MD (Doctor of Medicine) after a B.Sc. in Cardiology without an MBBS degree.
An MD is a postgraduate medical qualification that requires a foundation in general medicine, which is provided by the MBBS program.

This is the basic medical degree that qualifies you to practice medicine. It covers a broad range of medical topics and provides the necessary knowledge and skills to diagnose and treat various diseases.

This is a specialization program within the field of medicine focusing specifically on the heart and circulatory system. To be eligible for this program, you need an MBBS degree first.

https://medicine.careers360.com/download/sample-papers/aiims-mbbs-2013-sample-paper

I hope it helps!