A new algorithm speeds the diagnosis of acute myocardial infarction (AMI) in ED patients with chest pain. Researchers measured levels of high-sensitivity cardiac troponin T (hs-cTnT) when patients arrived at the ED, then again one hour later. AMI was ruled in when baseline hs-cTnT levels were 52 ng/L or higher or if they had increased 5 ng/L in the first hour. AMI was ruled out when baseline hs-cTnT levels fell below 12 ng/L and the first hourly change was less than 3 ng/L. Among 436 ED patients with acute chest pain, the algorithm diagnosed AMI in 17%. AMI was ruled out in 60%, and 23% remained under observation. The 30-day survival rate was 95.3% with a ruled-in AMI, 99.8% in those with an AMI ruled out, and 98.6% in those undergoing continued observation. The algorithm, described in the September 10 Archives of Internal Medicine, may prevent unnecessary blood sampling and shorten the time to AMI diagnosis and treatment.