In acute coronary syndromes, risk stratification is essential, particularly in patients without ST elevation, and is based upon clinical, electrocardiogram (ECG), and biological markers. Among them, recent and repeated attacks of angina, ST-segment deviation from baseline on the admission ECG as well as elevated markers of myonecrosis (particularly increased troponin levels), myocardial dysfunction (B-type natriuretic peptide [BNP]; N-terminal prohormone of BNP[NT-proBNP]), and inflammation (high-sensitivity C-reactive protein) are predictors of an adverse outcome. These variables can be incorporated into broader risk predictive scores, among which the TIMI (Thrombolysis in Myocardial Infarction) and GRACE (Global Registry of Acute Coronary Events) scores are the most widely used. Two general therapeutic strategies (routine invasive vs conservative or selective invasive) are employed in the treatment of non-ST-segment elevation acute coronary syndrome (NSTEACS). Evidence-based analysis and the current American College of Cardiology/American Heart Association/Society for Cardiac Angiography and Interventions clinical practice guidelines recommend an early invasive treatment strategy (8-24 h) for intermediate or high clinical risk patients with NSTEACS.