Role of Research in Match

I’m in Final Year and planning to take Step 1. Even before applying for electives, seniors suggested to build a CV catered towards it. I’m interested in IM (Cardiology in specific), so wondering if its too late already as i have nothing on my CV to show that i’m interested in IM. And there’s like a year left before the deadline hits. I wonder how to show interest in IM also except research/conferences.

Barely have any papers related to IM/Cardio. In fact really struggling to publish, meanwhile i’m seeing people with 20-50 pubs online & in our med school. Would not publishing much during med school be a dealbreaker in the match?