255 Out-of-Hospital Fluid Diagnostics in Patients Complaining of Chest Pain

Abstract

Serum is commonly used for cardiac biomarker analysis to aid in diagnosis of acute myocardial infarction. However, saliva is emerging as a novel diagnostic fluid for identifying biomarkers of disease. A salivary biomarker “fingerprint” is currently being evaluated for usefulness in identification of the cardiovascular disease cascade. One of the drawbacks of fluid marker analysis using current technology is the delay in obtaining laboratory results. This delay slows interpretation and diagnosis of disease. Lab-on-a-Chip Point of Care technology employs a multiplexed assay for biomarkers that can be conducted rapidly on small fluid samples without requiring the traditional laboratory infrastructure. This technology has the potential to rapidly deliver objective data in the out-of-hospital environment. The ultrasensitive nature of such a multiplexed assay may provide a reliable diagnostic tool for biomarker identification of the non S-T segment elevation acute myocardial infarction. This study was conducted as a proof of concept for the out-of-hospital use of point-of-care fluid diagnostics to aid in the diagnosis of acute myocardial infarction. Paramedics from a large urban EMS system were recruited and trained to obtain consent and sample collection. Subjects were selected from 911-summoned EMS patients who were complaining of chest pain suggestive of cardiac ischemia for enrollment. In addition to the standard chest pain management, the paramedic obtained verbal consent, hospital records release, a brief cardiac and oral health history, a copy of the 12-lead electrocardiogram, and samples of blood and saliva. The blood sample was obtained from the intravenous catheter introduced as standard of care, and the saliva sample was obtained by use of an oral swab. The saliva and blood samples were processed, packaged and sent to the laboratory for biomarker analysis. A board certified cardiologist, blinded to the biomarker results, made the determination of myocardial infarction from inpatient records. The diagnosis and laboratory results were evaluated for concordance. To date 63 subjects have been enrolled in the study. Subjects have been: 63% male, 47% Hispanic, 31% Caucasian, and 14% African American. Of 63 subjects enrolled, 6 have been diagnosed with acute myocardial infarction. Preliminary data on select patients diagnosed with acute myocardial infarction indicate elevation of myeloperoxidase, C-reactive protein, myoglobin, Interleukin 1β and myoglobin in saliva, and myoglobin, C-reactive protein, and troponin I in serum. In patients diagnosed with congestive heart failure there were elevations in NT-ProBNP, BNP, and myoglobin in serum. This pilot study indicates that point-of-care technology can detect both salivary and serum biomarkers in patients suffering either myocardial infarction or congestive heart failure in the out-of-hospital environment. Other studies currently being conducted will determine the optimal diagnostic fluid as well as validate the panel of markers to rapidly diagnose cardiac disease. Once the optimal marker panel is identified, a multicenter trial will be conducted to determine sensitivity and specificity of point-of-care technology in the diagnosis of out-of-hospital myocardial infarction.