Abstract 9446: Usefulness of Platelet Retention Assay for Diagnosing Acute Coronary Syndromes and Predicting Clinical Outcome in Patients with Chest Pain and/or Shortness of Breath

Abstract

Measurement of platelet retention rate (PRR) using a collagen-coated bead column and whole blood as a sample is a new point-of-care assay that reflects platelet aggregate formation. We have previously reported an equivalency of the PRR assay with PFA-100 and light-transmission aggregometry to assess the platelet function. This assay is very simple, low-cost performance and takes < 5 min for all procedure. We tested the hypothesis that the PRR assay may be useful for early diagnosing acute coronary syndromes (ACS) and predicting clinical outcome in patients with chest pain and/or shortness of breath of uncertain origin. Methods and Results: The citrated whole blood (1.5 ml) in a syringe was passed through a column with collagen-coated beads (0.1-0.2 mm diameter) using a syringe pump. The PRR in the column was calculated by difference between platelet counts in the blood samples before and after the passage. As retention rate rises, so does platelet aggregability. The PRR was measured at admission in the 129 consecutive patients who were admitted for chest pain and/or shortness of breath of recent onset (< 24 hrs). Of the enrolled patients, 59 (45%) patients had the discharge diagnosis of ACS, and the remaining 70 patients (55%) had non-ACS. The high PRR (>30%, as determined by ROC analysis) provided 78% of sensitivity and 79% of specificity in identifying ACS patients, and the addition of PRR increased the diagnostic power of troponin T (TropT) and CKMB (AUC; combination with PRR 0.80 and 0.91 vs. without PRR 0.62 and 0.80, respectively, p < 0.01). Cardiac events recurred after discharge in 16 patients (1 cardiac death, 1 non-fatal MI, and 14 coronary revascularization) during 1-year follow-up period. The higher PRR had a significant predictive value of the future events, that was independent of use of anti-platelet medications, TropT, C-reactive protein, brain natriuretic peptide (HR 2.2, 95% CI 1.3-71.9, p < 0.01). The addition of PRR increased the predictive ability of TropT (AUC; combination with PRR: 0.80 vs. without PRR 0.62, p < 0.01). Conclusions: In triage of patients with chest pain and/or shortness of breath, the platelet retention rate assay may be useful for fast diagnosis of ACS and early risk stratification along with other conventional biomarkers.