 Cardiac electrophysiology is considered a subspecialty of cardiology in most countries and usually requires two or more years of fellowship training beyond a general cardiology fellowship.In early 2011, the Centers for Medicare and Medicaid Services (CMS) promoted cardiac electrophysiology to its own specialty category in the United States.Cardiac electrophysiologists are trained to perform interventional cardiac electrophysiology studies (EPS) as well as surgical device implantations.