Repeatability of Platelet Aggregation Characteristics Using Impedance Aggregometry With and Without Aspirin Intervention

Abstract

Nearly 40% of adults over 50-years-old regularly take aspirin for primary or secondary prevention of cardiovascular disease and/or adverse cardiovascular events. The effcacy of aspirin therapy is commonly assessed with light transmission aggregometry. However, this method requires removal of large platelets as well as the mechanical disturbance of platelets remaining to be tested in the sample. Impedance aggregometry presents a solution to this problem, but the repeatability of impedance aggregometry analysis remains to be tested. We hypothesized repeated impedance aggregometry analysis would show decreased platelet aggregation activity following aspirin intervention compared with control visits. Venous blood samples were obtained from ten participants on three occasions each, separated by at least two weeks. One sample followed seven days of aspirin intervention (81 mg once daily; ASA) and the other two with no intervention (control). Platelet aggregation was induced using 1 μg/ml collagen (Col1), 5 μg/ml collagen (Col5), and 0.5 mM arachidonic acid (AA) via impedance aggregometry to determine area under the aggregation curve (AUC, au), time to aggregation initiation following addition of reagent (Lag, s), the rate of aggregation (Slope), and the maximal aggregation (Amp, Ohms). These characteristics were statistically analyzed for an impact of aggregometer channel (intra-test repeatability), visit (inter-test repeatability), intervention (ASA or control), and incubation (samples were incubated with either saline or Terutroban solution to block thromboxane receptors). Results were analyzed by multiple paired t-tests and represented with lowest relevant p-value if insignificant or highest relevant p-value if significant. Impedance aggregometry revealed no difference in any aggregation characteristics (AUC, Lag, Slope, or Amp) for duplicate samples (all p ≥ 0.10) or visits (all p ≥ 0.06). ASA decreased AUC, Slope, and Amp while increasing or completely inhibiting Lag response to the addition of all reagents (all p ≤ 0.01). Terutroban incubation had no effect on aggregation characteristics following the ASA intervention (all p ≥ 0.09), but attenuated the AUC, Slope, and Amp (all p ≤ 0.01), and entirely prevented or substantially increased the Lag response to AA (p ≤ 0.01) without impacting the responses to Col1 or Col5 (all p ≥ 0.24). These findings suggest the impedance aggregometry approach is a repeatable method for platelet aggregometry analysis for the characteristics of AUC, Lag, Slope, and Amp. NIH R01 Grant 1R01AG067471-01 NIH F31 Grant 1F31HL170616-01. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.