Rapid Blood Test Detects Myocardial Infarction

A sensitive assay has been used to detect myocardial infarction (MI) within two hours of a patient being admitted to hospital.

An increase in the concentration of troponin in the blood is used to detect whether patients with acute coronary syndrome (ACS) have myocardial infarction and this can be used as a diagnostic marker.

A study performed at the Catharina Hospital, (Eindhoven, The Netherlands), examined the concentration of troponin in 157 patients with suspected non-ST elevated ACS. Blood was drawn on arrival (T0) and 2 (T2), 6 (T6) and 12 (T12) hours later. Levels of cardiac troponin I, creatine kinase–myocardial band fraction (CK-MB) and myoglobin were measured on an immunochemistry analyzer. The assay for troponin was the second-generation TnI-Ultra troponin kit and all tests were analyzed on the manufacturer's Advia Centaur analyzer, (Siemens Healthcare Diagnostics; Erlangen, Germany).

The TnI-Ultra troponin kit is a second-generation, high-sensitivity test with a 10% coefficient of variation (CV) at 0.05 μg/L and a troponin concentration of 0.06 μg/L at the 99th percentile of a reference population. The 99th percentile was established on 221 samples from outpatients with no history of myocardial disease. At T2, a troponin concentration above the MI cutoff is 87% sensitive and 100% specific for MI detection. A difference of more than 30% between the troponin measurements at T0 and T2 in the absence of an absolute troponin increase above the 99th percentile of a reference population was also considered indicative of MI, the sensitivity increases to 100% and specificity decreases to 87%.

The authors concluded that by using a sensitive troponin assay and simple algorithms, the diagnosis of MI can be determined within two hours after arrival at the emergency department, and the measurement of myoglobin and creatine kinase–MB has no added value. The study was published in March 2011 in the American Journal of Clinical Pathology.

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