Abstract: The disclosure provides methods for detecting circular endothelial cells (CECs) in a non-enriched blood sample. The present disclosure is based, in part, on the unexpected discovery that CECs can be detected in non-enriched blood samples. The present disclosure is further based, in part, on the discovery that CECs can be detected in non-enriched blood samples by combining the detection of one or more immunofluorescent markers in the nucleated cells of a non-enriched blood sample with an assessment of the morphology of the nucleated cells. The present disclosure is further based, in part, on the discovery that CECs can be detected in non-enriched blood samples by comparing the immunofluorescent marker staining and morphological characteristics of CECs with the immunofluorescent marker staining and morphological characteristics of WBCs. The methods disclosed herein serve to classify human subject in myocardial infarction (MI) patients or healthy controls.