False Positive Troponin – A True Problem

Abstract

Summary Cardiac troponins have a crucial role in diagnosing acute myocardial infarction, but have been considered by some authors to have a high false positive rate. Such opinions may decrease the confidence in troponin with important clinical consequences. The aim of the paper is to analyze three different meanings of the phrase »false positive troponin«: A) analytic (technical) false positive, with no real myocardial damage; B) false positive considering AMI: cardiac injury is present, but there is no AMI; C) false positive considering CAD: there is myocardial damage, but no CAD. The most frequent and the most important source of misunderstanding is the confusion between aspects A) and B). Namely, there has been a relatively small percentage of false positive troponin elevations due to analytic reasons. On the contrary, there has been a re - latively large percentage of »false positive« results in patients with myocardial necrosis due to causes other than AMI; for them - instead of »FP troponin elevation« - another phrase ought to be used, e.g., »non-AMI troponin elevation « until the etiopathogenesis in an individual patient is recognized. The phrase »false positive troponin« should be restricted to the artificial increase in troponin due to preanalytic and analytic reasons. By doing so, we may decrease the degree of confusion about troponin and increase the confidence in this highly specific marker of myocardial injury. The possibility of an analytic false positive result should always be kept in mind when one interprets elevated troponin.

Dipyridamole Stress Echocardiography Does Not Trigger Release of Highly-Sensitive Troponin I and T

“…Based on the availability of these HS immunoassays, several models for troponins release have been proposed, and it is now widely accepted that these proteins are released in many situations other than frank cardiomyocyte necrosis (25)(26)(27). The non-necrotic release of cardiac troponins has been attributed to leakage of free cytosolic pool, through a specific mechanism that involves the generation of the socalled cytoplasmatic »blebs«, containing a large amount of intracellular material.…”

Multicenter Comparison of Four Contemporary Sensitive Troponin Immunoassays

“…This recommendation has, however, been mostly overlooked in the current scientific literature, since there are only two studies that have compared different TnI and TnT methods for establishing the 99 th percentile values from a common, presumably healthy population (17)(18)(19). Even more importantly, no previous study has directly compared TnI values obtained with four of the most frequently used contemporary sensitive immunoassays in the same population, to the best of our knowledge.…”

Biomarkers in aortic dissection, including specific causes of troponin elevation

“…Asymptomatic patients with end-stage renal disease had increased cTnT in 12%-66% and cardiac troponin I (cTnI) in 0.4-38%. Elevated cTnT significantly correlated with all-cause mortality [relative risk (RR) 2.64; 95% CI: 2.17-3.20] and with cardiac death (RR 2.55; 95% CI: 1.93 to 3.37), as demonstrated in a meta-analysis 2,16 . The exact mechanism is not definitely elucidated, but current explanations for cTn elevations are: asymptomatic necrosis of cardiomyocytes, left vetricle (LV) hypertrophy, LV systolic dysfunction, enhanced cardiac preload accompanied by myocardial stretch, endothelial dysfunction, microvascular derangement, episodes of hypotension during dialysis or myocardial lesion due to calcium and oxalate deposition 26 .…”

“…Renal failure has been known to enhance cTn values, especially of cardiac troponin T (cTnT) 2,16 . Asymptomatic patients with end-stage renal disease had increased cTnT in 12%-66% and cardiac troponin I (cTnI) in 0.4-38%.…”

“…The expression "false positive cTn" should be reserved for preanalytical and analytic false positives [i.e. when cTn elevation is not really present, but it is due to methodological problem(s)] 2 . cTn is also useful prognosticator in acute myocardial infarction (AMI) 3 .…”