Infarct size assessment through necrosis biomarker release estimation by kinetic modelling: Toward a new gold standard?

Background Infarct size, a key prognostic factor in ST-segment elevation myocardial infarction (STEMI), is best assessed by late gadolinium enhancement in cardiac magnetic resonance imaging (MRI). MRI availability being limited, necrosis biomarkers (peak concentration and/or area under the concentration versus time curve (AUC)) are used as surrogate markers of infarct size. These methods, excluding biomarkers kinetic data, may provide inaccurate results. We recently developed and published about compartmental kinetic models allowing estimation of the total amount of necrosis biomarker released in STEMI, A0, with reduced blood sampling. Purpose We sought to evaluate the correlation between A0 of necrosis biomarkers and MRI measurements of infarct size in STEMI patients. Methods We retrospectively included all STEMI patients with timely reperfusion and a cardiac MRI in the early recovery period in Tours University Hospital (France) from February 2015 to September 2017. Kinetics of Creatine kinase (CK), troponin I (cTnI) and/or T (cTnT), were described using our models and we compared the maximum concentration (Cmax), estimated AUC and A0 to MRI measurements of infarct size. Results Forty-one patients were included; all had CK assays, 16 had cTnI assays and 25 hs-cTnT assays. Our population had similar characteristics to the STEMI population reported in the latest FAST-MI registry. The models described satisfactorily biomarker kinetic data. Infarct size was correlated with all CK and hs-cTnT parameters, particularly cTnT A0 (R2 = 67,1%) and CK Cmax (R2 = 64,8%). The correlation was lower with cTnI parameters ( Fig. 1 ). Conclusion Our models described accurately necrosis biomarkers kinetics following STEMI. The total amount of hs-cTnT released and estimated CK peak concentration were best correlated to MRI infarct size and may be used as easy and accurate estimators of infarct size. This method may be a major advance for future clinical trials on cardioprotection.