In acute coronary syndrome (ACS), there is an increase in cortisol levels, as an expression of the stress response, and C-reactive protein, as an expression of the inflammatory response, which are in turn associated with changes in the components of cellular immunity, and ultimately are predictors of clinical events. The objective of this study is to demonstrate that, within the frame of reference of ACS, beyond the thrombotic phenomenon that leads to ischemia and myocardial necrosis, there is an activation of an inflammatory and stress response, evidenced by an elevation of CRP and cortisol, respectively, and sequentially modifications in the components of cellular immunity in peripheral blood that convey prognostic value during hospitalization and after discharge. A prospective, observational, analytical, unicentric study of consecutive patients with ACS, with telephone follow-up to 6 months, will be carried out. For 2 years, all eligible patients admitted with a diagnosis of ACS to the Coronary Care Unit of the Hospital de Clínicas José de San Martín in Buenos Aires will be registered consecutively.