Abstract 16805: Assessing Correlation and Agreement in Activated Clotting Time (ACT) Measurement Using Hemochron Signature Elite

Abstract

Introduction & Hypothesis: ACT is the preferred mode of assessing degree of anti-coagulation during cardiac catheterization. Studies have shown significant variability in ACT measurement with different company analysers. We aimed to assess correlation and agreement between two instruments of the same company, Hemochron Signature Elite. Method: Paired samples were collected before and after heparin administration for each patient. Each paired sample was collected and entered into the two instruments tagged A & B using the same syringe and at the same time. Results: A total of 46 samples were included in the study. There was a significant correlation between the two instruments (r= 0.92, p- value 0.02). However, the two devices had significant discordance with a mean bias of 11.1 , 95% CI 0.77 to 24.9 and limits of agreement -35.8 to 58.1. Mean ACT between the two devices was significantly different (231 vs 248, p-value 0.01). Inter-device reliability was 30%. There was a more than 10% difference in about 30% of the paired samples and more than 20% difference in 9% of the samples. Conclusion: Significant correlation but discordance exists in ACT measurement even between the same type of device. This may affect clinical decision making during cardiac procedures and need further investigation.