This procedure is indicated in all patients with aspirin or NSAID intolerance with imperative cardiological indications for aspirin, such as acute coronary syndrome, or placement of a stent. The desensitization procedure must be performed in a coronary care unit; the patients are duly informed about benefits and risks of the challenge and provide written informed consent. Desensitization consists in rapidly escalating aspirin dose administration with ad hoc aspirin capsules prepared by the hospital pharmacist. Blood and urinary samples are obtained during the hospital stay for coronary and desensitization care. An additional blood and urine sample will be obtained 6 to 8 weeks later during an outpatient visit in the laboratory. Initial biological data will be compared to those of two control groups matched for age, gender and type of acute coronary syndrome :