In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: AIMS : To investigate whether alterations of myocardial strain and high - sensitive cardiac troponin T ( cTnT ) could predict future cardiac dysfunction in patients after epirubicin exposure .
### Output Text:
AIMS : To investigate whether alterations of myocardial strain and high - sensitive cardiac troponin T ( cTnT ) could predict future cardiac dysfunction in patients after <span class="chemical">epirubicin</span> exposure . 