RESUMO
AIMS: Evaluating myocardial infarct (MI) size prior to intervention is fundamental to ensure accurate results in experimental studies. However, this assessment is performed at late time points. We aimed to evaluate whether measuring plasma cardiac troponin I (cTnI) and performing echocardiographic assessment at earlier time points can predict the occurrence of MI and infarct size. MAIN METHODS: Male Wistar rats were subjected to MI (n=40) or sham surgery (n=11). cTnI levels were measured 2 and 8h after MI. Echocardiographic evaluations were performed at 48h and 14days post-MI. After 14days, the animals were euthanized, and the hearts were removed and paraffin-embedded for Sirius red staining. KEY FINDINGS: cTnI plasma levels increased in the MI group relative to the sham group at 2h after MI (7.2±9.4ng/mL vs. 2.3±1.0ng/mL; p<0.01) with a further increase at 8h after MI (22.2±13.5ng/mL vs. 1.5±1.7ng/mL; p<0.001). cTnI levels (8h) and echocardiographic outcomes correlated with histological infarct size 14days after MI (r=0.74, p<0.001 and r=0.84, p<0.001, respectively), but only echocardiography could confidently identify small, medium, and large infarcts. Additionally, using a cutoff value of 4.8ng/mL we achieved 100% specificity and 91% sensitivity in detecting MI. SIGNIFICANCE: A cutoff value of 4.8ng/mL for cTnI could be used as early as 8h after MI to accurately identify infarct in this model, whereas echocardiographic images taken 48h after MI predicted the infarcted area 14days after MI.
