High sensitivity troponin assay

High sensitivity troponin assay

Estimation of cardiac troponins is a popular way to assess myocardial damage. Conventional troponin assays are useful for diagnosing myocardial necrosis within a few hours to about two weeks. New high sensitivity assays are being developed which can detect smaller levels of troponins in the circulation much earlier than conventional assays which are commercially available now. In a study of patients with documented myocardial injury, 64% of the early samples which were negative by conventional assays had troponin levels detectable by the new high sensitivity methods [1].
Before using high sensitivity methods in clinical practice, due consideration has to be given to the relevance of the mild elevations of troponins which can be detected by these highly sensitive methods. While detection of cardiac troponins in circulation definitely mean myocardial necrosis, it need not mean acute coronary syndrome as the cause of necrosis as is often thought. There are other conditions like septicemia, heart failure and pulmonary embolism which can cause myocardial necrosis without an acute coronary syndrome. Hence troponin results should be interpreted only in the clinical context with the history and electrocardiogram to guide us. Otherwise, undue reliance on high sensitivity troponins will lead to an over diagnosis of acute coronary syndromes, many of which may turn out to be false positive.

As anticipated by the authors, high sensitivity cardiac troponin assays have become a tool for the early diagnosis of myocardial necrosis in acute coronary syndromes with implications in prognosis and management. The non infarction elevations of high sensitivity troponin has been classified as myocardial injury which has prognostic significance, though not amenable to treatment modalities for acute myocardial infarction.

Reference

1. Stacy E F Melanson, David A Morrow, Petr Jarolim. Earlier detection of myocardial injury in a preliminary evaluation using a new troponin I assay with improved sensitivity. Am J Clin Pathol. 2007 Aug;128(2):282-6.