Cardiac Troponin I Associated with the Development of Unrecognized Myocardial Infarctions Detected with MRI Charlotte Ebeling Barbier, 1* Raquel Themudo, 1 Tomas Bjerner, 1 Lars Johansson, 1,2 Bertil Lindahl, 3 Per Venge, 3 Lars Lind, 3 and Håkan Ahlström 1 BACKGROUND: Late enhancement MRI (LE-MRI) and cardiac troponin I (cTnI) are sensitive methods to de- tect subclinical myocardial injury. We sought to inves- tigate the relation between plasma concentrations of cTnI measured with a high-sensitivity assay (hs-cTnI) and the development of unrecognized myocardial in- farctions (UMIs) detected with LE-MRI. METHODS: After approval from the ethics committee and written informed consent were obtained, LE-MRI was performed on 248 randomly selected community-living 70-year-old volunteers and hs-cTnI was determined with a highly sensitive premarket assay. Five years later these individuals were invited to a second LE-MRI, and 176 of them (82 women, 94 men), who did not have a hospital diagnosis of MI, constitute the present study population. LE-MR images were analyzed by 2 radiologists indepen- dently and in a consensus reading, blinded to any infor- mation on previous disease or assessments. RESULTS: New or larger UMIs were detected in 37 partici- pants during follow-up. Plasma concentrations of hs- cTnI at 70 years of age, which were mainly within what is considered to be the reference interval, were related to new or larger UMIs at 75 years of age with an odds ratio of 1.98 per 1 unit increase in ln-transformed cTnI (95% CI, 1.17–3.35; P = 0.010). Plasma concentrations of hs-cTnI at 70 years of age were associated with the volumes of the UMIs detected at 75 years of age (P = 0.028). CONCLUSIONS: hs-cTnI in 70-year-old community- living women and men was associated with the devel- opment of MRI-detected UMIs within 5 years. © 2014 American Association for Clinical Chemistry Measurement of cardiac troponins in plasma is a highly sensitive method to detect myocardial damage (1–3 ). Increased plasma concentrations of cardiac troponin have substantial prognostic importance in patients (4) and in population-based samples (1, 2 ). The ability to detect very low concentrations of cardiac troponin in plasma is constantly improving, and high-sensitivity (hs) 4 assays are now available that are capable of mea- suring cardiac troponin for both cardiac troponin T (cTnT) and cTnI in the vast majority of healthy indi- viduals (5). The prevalence of unrecognized myocardial in- farctions (UMIs) has formerly been estimated with electrocardiography (ECG) (6). However, late en- hancement MRI (LE-MRI) is a highly sensitive method to detect myocardial scars (7) that has revealed a higher prevalence of UMIs in the general population than pre- viously expected (8, 9 ). Like increased plasma concen- trations of cardiac troponin, these MRI-detected UMIs have important prognostic value in patients (10 ) and in population-based samples (9), even if some of the UMIs are very small (11 ). However, no association has been established between the concentrations of cardiac troponin and MRI-detected UMIs (12 ). The aim of the present study was to investigate the relation between plasma cTnI concentrations as mea- sured with an hs assay (hs-cTnI) and the development of MRI-detected UMIs. Materials and Methods STUDY POPULATION After we obtained approval from the ethics committee and written informed consent from all study partici- pants, cardiac MRI was performed on an unselected 1 Department of Radiology, Uppsala University, Uppsala, Sweden; 2 Astrazeneca, Gothenburg, Sweden; 3 Department of Medical Sciences, Uppsala University, Uppsala, Sweden. * Address correspondence to this author at: Department of Radiology, Uppsala University Hospital, 751 85 Uppsala, Sweden. Fax +46-18557279; e-mail Charlotte.Ebeling_Barbier@radiol.uu.se. These data have been presented at a scientific paper presentation at the 99th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA) in Chicago on December 5, 2013. Received February 15, 2014; accepted July 8, 2014. Previously published online at DOI: 10.1373/clinchem.2014.222430 © 2014 American Association for Clinical Chemistry 4 Nonstandard abbreviations: hs, high-sensitivity; cTnT, cardiac troponin T; UMI, unrecognized myocardial infarction; ECG, electrocardiography; LE-MRI, late enhancement magnetic resonance imaging; hs-cTnI, cTnI measured with an hs assay; PIVUS, Prospective Investigation of the Vasculature in Uppsala Seniors; ECG, electrocardiogram; LVM, left ventricular mass; EF, ejection fraction; NoLE, nonviable myocardium; Other LE, LE that did not represent any MI scar (i.e., not involving the subendocardial layer); NT-proBNP, N-terminal pro-brain natriuretic peptide; GFR, glomerular filtration rate; CHD, coronary heart disease; FRS, Framingham Risk Score; MACE, major adverse cardiac event; Old UMI, UMI that had not increased in size during follow-up; OR, odds ratio. 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