High sensitivity troponins and conventional troponins at the bedside

Abstract

The continuing advances in the biochemical research for the discovering an ideal biomarker for diagnosing myocardial injury have led to discovery cardiac Troponin, a biochemical gold standard for myocardial necrosis. Further with advances in the immunoassay techniques, the 99th percentile cutoff value of cardiac troponin required for the diagnosis of myocardial infarction decreased, with the latest available ultrasensitive cardiac troponin assay capable of measuring level as low as 0.005 ng/ml. Troponin have both diagnostic as well as prognostic significance in myocardial necrosis, but the cut off value by 99th percentile rule is useful only when applied to patients with a high pretest probability of Acute Coronary Syndrome(ACS) and also the results must be interpreted in the context of clinical history, ECG findings, and possibly cardiac imaging to establish the correct diagnosis. As cardiac troponins are also elevated in other cardiac conditions such as cardiomyopaties, the serial monitoring of the cardiac troponin level along with the absolute value would help to differentiate myocardial infarction from these many varied conditions, with the interval of serial assay being reduced to 3 hours. The aim of this review is to complement the advantages, to emphasize on proper interpretation of positive results, to appraise the challenges faced with the available cardiac troponin assays and need for further research to overcome them and build up the most ideal cardiac marker for diagnosing the myocardial infarction.

Keywords: Acute coronary syndrome; cardiac troponin; myocardial infarction.

Figure 1

Evolution of the cardiac troponin (cTn) assays and their diagnostic cutoffs. A hypothetical case of acute coronary syndrome is depicted with the earliest times of potential diagnosis corresponding to the diagnostic cutoffs of more sensitive cTn assays. The years correspond to the availability of the respective assays in the US market