Compared to ST-elevation myocardial infarction the ability of electrocardiography (ECG) to predict coronary anatomy in cases with acute coronary syndrome without ST-segment elevation is rather limited. However, certain sub-groups with distinct ECG patterns and varying risk profile can be defined. Differentiating ischaemic ECG patterns may help in clinical decision making for the individual patient. Modern technology makes it possible to get an interpretation of the ECG findings within minutes from an expert situated even in another country. Based on our experience an old method, 12-lead ECG, is still an important tool in clinical decision-making in patients with acute coronary syndrome in the catheterization laboratory.