This study has been carried out at the " Centre Universitaire Hospitalier Arnaud de Villeneuve", Montpellier, France, jointly with the University of Padua, Italy. Increased evidence has shown that, despite the highest level of care for all the patients admitted with acute coronary syndrome, a residual risk of mortality remains, in which obstructive sleep apnoea appears to be a largely undiagnosed factor, particularly in the intensive cardiac care unit. The purpose of this study is to determine whether the systematic screening for sleep disordered breathing in this context is feasible and may be recommended. In the first part, a comprehensive description of what obstructive sleep apnoea syndrome is, will be provided from its definition to its treatment, throughout its pathophysiological mechanisms and their consequences on cardiovascular system. In the second part, the results of the study will be discussed into details.