Specific data: Number of patients seeking attendance in CPU per day (crowding index), GRACE score, secondary risk factors present or not (leftventricular ejection fraction (LVEF) < 40%, glomerular filtration rate< 60 ml/min, Diabetes mellitus, previous myocardial infarction (MI), previous CABG, prior PCI, ST segment depression). Rule-out protocols are stratified by hour ± 30 min, i.e. 0-1 h (±30 min), 0-2 h (±30 min), 0-3 h (±30 min) etc.