Chest pain is a common reason why cocaine-addicted patients call the emergency department, and acute coronary syndromes are difficult to diagnose in these situations. A 30-year-old cocaine-user patient contacts the Emergency Medical Assistance Service with constrictive chest pain. A doctor is sent out to the patient at home. The initial ECG is normal. No other aetiology of chest pain is revealed, except nicotine and cocaine addictions. First, a coronary artery spasm is suggested, caused by the injection of cocaine. During the journey, the patient indicates that the chest pain has returned. A 12-lead ECG shows repolarisation abnormality in the form of a subepicardial ischaemia. Fibrinolysis is not prescribed in view of the patient's history and of the proximity of the interventional cardiology team. The coronary angiogram enables the diagnosis of myocardial bridging in the middle anterior interventricular artery, and no significant lesion of the coronary arteries is noted. A particular feature of prehospital management in France is that medical care can be given in the early stages by a physician who is called by the patient. This case report discusses the specific care requirements of which the emergency physician needs to be aware in the context of this unstable clinical situation due to the urgency associated with the difficulties of ECG diagnosis of ST-segment elevation in cocaine users.