Circulation and its family of journals, I would consider them highly esp if you are looking at the research side of cardiology.
I particularly like ATVB ( Arteriosclerosis, Thrombosis and Vascular biology) you will find something for you in their group
http://www.ahajournals.org/circportfolio/
JACC of course is the main journal publishing the main clinical trails and the guidlines of the ACC many of the ground breaking studies and perspectives in cardiology, however find their way easily and are published in the NEJM and lancet.
subscriptions to these publications might be expensive though. you get them through your institution usually