Abstract. During the last few years studies have shown that an invasive strategy is superior to a conservative one in high-risk patients with acute coronary syndrome without ST-segment elevation. An improved outcome can be achieved by a combination of optimal medical therapy including GP IIbIIIa inhibitors and percutaneous intervention within 48 h or coronary bypass surgery within a few days. In ST-elevation MI PCI is superior to thrombolysis if performed by an experienced team within 90 minutes from the first medical contact of the patient. 12 (-15) lead ECG recorded during acute ischaemia caused by impaired coronary artery flow is seldom normal, and is of diagnostic, therapeutic and prognostic significance. Coronary angiography gives detailed information about coronary anatomy. Often patients have more than one stenosis. It is important to know which is the culprit lesion for different reasons. In patients with ST-elevation MI it is recommended to treat only the culprit lesion in the acute phase. This in not always easily defined by angiography if none of the coronary arteries are totally occluded. In some cases the culprit lesion is evident by the type of lesion. This is not always the case. In elderly patients partial revascularization is often justified because the goal of therapy is more improvement of quality of life than prolongation of life. During the presentation cases from our hospital are presented to show how we combine the anatomical and physiological information in ECG with the anatomical information of the angiographies to try to optimise the therapy. As clinicians we have to make the decisions individually for every patient. Results of large studies only help to a limited extent in real life. The way we have been working for the last few years are based on information from the literature, clinical experience and sound clinical judgement. In cases with ST-elevation MI and no totally occluded coronary artery, we go back to the ECG and define which one is the probable culprit lesion. In inferior MI with stenoses both in the circumflex and right coronary artery, we tend to treat only the one that had caused the acute occlusion. If not considering the ECG finding during the acute phase, wrong lesion could be treated. It may be disastrous for the patient to teat a pre-existing stenosis in a coronary artery supplying the border zone of the MI, if the PCI procedure is complicated by occlusion of the treated artery. It is not unusual that the grade of stenosis in the culprit lesion is less than that of the neighbouring artery. The non-culprit lesion(s) can be treated later if needed. We think that ECG gives important information about the completeness of myocardial reperfusion. In cases with signs of complete myocardial reperfusion, including negative T waves, we may postpone the PCI procedure for 24-48 hours if the clinical situation is stable and the patient is not on optimal antithrombotic therapy (especially GP IIbIII inhibitor) at the time of angiography. We believe that this diminishes the risk of microembolization. In cases with acute coronary syndrome without ST-segment elevation not many conclusions can be drawn about the coronary anatomy. However, in patients with ST-segment depression maximally in the chest leads, the type of ischaemia may influence our choice of invasive therapy. In cases with maximal ST-segment depression in leads V4-5 with negative T waves (circumferential subendocardial ischaemia) we prefer urgent bypass surgery. In cases with ST-segment depression maximally in leads V2-4 with positive T waves (regional subendocardial ischaemia) we may perform PCI of the LAD or a diagonal branch, whichever is the culprit lesion. In cases with ST-segment depression as a sign of posterior injury (ST-elevations in leads V7-9), we may consider PCI of a distal stenosis of the circumflex artery. Finally, in my opinion the important diagnostic, therapeutic and prognostic information contained in ECG recorded during episodes of rest angina is largely underutilized in clinical decision making in the era of sophisticated therapeutic strategies including optimal antithrombotic therapy, stenting and bypass surgery.