Know your troponin. There are multiple different troponin assays with different values for normal. Every physician needs to know what generation assay they are using, what the abnormal value is and how soon it turns positive (the ultra-high sensitivity troponins are positive within 1 hour. These are being used in Europe, but not in the US). Most troponins in the US change within 2-3 hours. The current American Heart Association recommendations are a 0 and 3 hour repeat and this was the same time frame used in the HEART score study.