RIsk of Apoplexia Cerebri in CLOpidogrel Non-responders

Stroke patients are given prophylactic treatment with clopidogrel to prevent new strokes. Some of these patients (the investigators don't know precisely how many, but previous studies indicate 4-34%) are so called non-responders, when you measure on a blood sample from the patient. These patients may have an increased risk for less effect of the treatment and therefore a higher risk for a new stroke. The investigators want to investigate if clopidogrel non-responders have a clinically increased risk of a new stroke by following the patients for two years. With this study the investigators aim to ensure that all patients get the best prophylactic treatment and reduce the risk of early death and dependency of others.