Received on September 30, 2008
Accepted on May 28, 2009

Point-of-Care Testing

Use of Saliva-Based Nano-Biochip Tests for Acute Myocardial Infarction at the Point of Care: A Feasibility Study

¹ Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX
² Department of Oral Health Practice, Center for Oral Health Research, College of Dentistry University of Kentucky, Lexington, KY
³ Mid-America Heart Institute, University of Missouri, Kansas City, MO
⁴ School of Dentistry, University of Louisville, Louisville, KY
⁵ Department of Dental Diagnostic Science, Dental School, University of Texas Health Science Center in San Antonio, San Antonio, TX
⁶ School of Medicine, University of Texas Health Science Center in San Antonio, San Antonio, TX
⁷ Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX; Center for Nano and Molecular Science and Technology, Texas Materials Institute, Austin, TX, and The University of Texas at Austin, Austin, TX

^* To whom correspondence should be addressed. E-mail: mcdevitt{at}mail.utexas.edu.

BACKGROUND: For adults with chest pain, the electrocardiogram (ECG) and measures of serum biomarkers are used to screen and diagnose myocardial necrosis. These measurements require time that can delay therapy and affect prognosis. Our objective was to investigate the feasibility and utility of saliva as alternative diagnostic fluid for identifying biomarkers of acute myocardial infarction (AMI) earlier in screening process.

METHODS: We used Luminex and lab-on-a-chip methods to assay 21 proteins in serum and unstimulated whole saliva procured from 41 AMI patients within 48 h of chest pain onset and from 43 apparently healthy controls. Data were analyzed by use of logistic regression and area under curve (AUC) for ROC analysis to evaluate the diagnostic utility of each biomarker, or combinations of biomarkers, in screening for AMI.

RESULTS: Both established and novel cardiac biomarkers demonstrated significant differences in concentrations between patients with AMI and controls without AMI. The saliva-based biomarker panel of C-reactive protein, myoglobin, and myeloperoxidase exhibited significant diagnostic capability (AUC = 0.85, P < 0.0001) and in conjunction with ECG yielded strong screening capacity for AMI (AUC = 0.96) comparable to that of the panel (brain natriuretic peptide, troponin-I, creatine kinase-MB, myoglobin; AUC = 0.98) and far exceeded the screening capacity of ECG alone (AUC approximately 0.6). En route to translating these findings to clinical practice, we adapted these unstimulated whole saliva tests to a novel lab-on-a-chip platform for proof-of-principle screens for AMI.

CONCLUSION: Complementary to ECG, saliva-based tests within lab-on-a-chip systems may provide a convenient and rapid screening method for cardiac events in prehospital stages for AMI patients.