Since patients with atrial fibrillation (AF) frequently have acute cardiac and non-cardiac conditions, it is common to detect AF in critically ill patients [ [1] Khoo C.W. Lip G.Y. Acute management of atrial fibrillation. Chest. 2009; 135: 849-859 Crossref PubMed Scopus (36) Google Scholar ]. Most data concerning the incidence of AF in critical areas come from surgical intensive care units (ICUs) [ [2] Cavaliere F. Volpe C. Soave M. Atrial fibrillation in intensive care units. Curr Anaesth Crit Care. 2006; 17: 367-374 Abstract Full Text Full Text PDF Scopus (7) Google Scholar ]. Few studies have explored different types of AF and the prognostic implications on critically ill patients in a non-surgical coronary care unit (CCU). Data regarding patients admitted to today's CCU with AF are largely taken from large registries usually restricted to acute coronary syndrome (ACS), but they are not reflective of the overall cohort of patients with AF admitted to a CCU. The objective of the present study was to investigate the prevalence of AF, its prognostic implications in terms of the development of new ischemic stroke, and the all-cause mortality associated with different types of AF in a non-surgical CCU.