Prehospital troponin T testing in the diagnosis and triage of patients with suspected acute myocardial infarction

Abstract

Prehospital electrocardiographic (ECG) diagnosis has improved triage and outcome in patients with acute ST-elevation myocardial infarction. However, many patients with acute myocardial infarction (AMI) present with equivocal ECG patterns making prehospital ECG diagnosis difficult. We aimed to investigate the feasibility and ability of prehospital troponin T (TnT) testing to improve diagnosis in patients with chest pain transported by ambulance. From June 2008 through September 2009, patients from the central Denmark region with suspected AMI and transported by ambulance were eligible for prehospital TnT testing with a qualitative point-of-care test (cutpoint 0.10 ng/ml). Quantitative TnT was measured at hospital arrival and after 8 and 24 hours (cutpoint 0.03 ng/ml). A prehospital electrocardiogram was recorded in all patients. Prehospital TnT testing was attempted in 958 patients with a 97% success rate. In 258 patients, in-hospital TnT values were increased (≥0.03 ng/ml) during admission. The prehospital test identified 26% and the first in-hospital test detected 81% of patients with increased TnT measurements during admission. A diagnosis of AMI was established in 208 of 258 patients with increased TnT. The prehospital test identified 30% of these patients, whereas the first in-hospital test detected 79%. Median times from symptom onset to blood sampling were 83 minutes (46 to 167) for the prehospital sample and 165 minutes (110 to 276) for the admission sample. In conclusion, prehospital TnT testing is feasible with a high success rate. This study indicates that prehospital implementation of quantitative tests, with lower detection limits, could identify most patients with AMI irrespective of ECG changes.