Not exactly cardio specific but EMCRIT and SMART EM deal with a lot of cardio topics just from their nature of acute care ER based topics. EMCRIT I listen to frequently and I enjoy. SMART EM dives deep into usually one topic each episode and dissects the evidence for or against a topic and can be very educational.
I also have a Medscape Cardiology podcast on my list as well one from theheart.org and one from Heartwire but haven't really listened to much on those yet.