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Evaluation of clopidogrel response in healthy cats using a novel viscoelastic test and thromboelastography
Tommaso Rosati1,2, Karl E Jandrey3, Joshua A Stern4,5
1WR Pritchard Veterinary Medical Teaching Hospital, University of California Davis, Davis, CA, United States.
Insights
Monitoring clopidogrel treatment in cats using thromboelastography (TEG) and Viscoelastic Coagulation Monitor (VCM) showed variability. Light transmission aggregometry (LTA) remains the gold standard, though TEG R-time may offer point-of-care utility.
Area of Science:
- Veterinary Medicine
- Cardiology
- Pharmacology
Background:
- Cats with cardiomyopathy are at high risk for arterial thromboembolism (ATE).
- Clopidogrel is used to prevent ATE, but feline responses vary.
- Effective monitoring of clopidogrel therapy in cats is crucial due to this variability.
Purpose of the Study:
- To evaluate thromboelastography (TEG) and Viscoelastic Coagulation Monitor (VCM) for monitoring clopidogrel therapy in cats.
- To compare the performance of TEG and VCM against light transmission aggregometry (LTA), the current gold standard.
Main Methods:
- Twenty-eight healthy cats were administered clopidogrel for seven days.
- Blood samples were collected at baseline and post-treatment.
- Samples were analyzed using TEG, VCM, and LTA.
Main Results:
- Light transmission aggregometry (LTA) showed significant decreases in maximum amplitude, slope, and area under the curve (AUC) post-treatment.
- Viscoelastic Coagulation Monitor (VCM) showed a significant increase in maximum clot firmness (MCF).
- Thromboelastography (TEG) showed significant changes in R-time, K, and alpha angle; a moderate negative correlation was found between TEG R-time and LTA AUC. Eight cats were identified as non-responders, with 6 exhibiting shortened R-time on TEG. VCM was less discriminatory.
Conclusions:
- Light transmission aggregometry (LTA) remains the gold standard for monitoring clopidogrel in cats.
- Unexpected changes observed with VCM and TEG may be due to interindividual variability and assay sensitivity.
- TEG R-time shows potential for point-of-care monitoring of clopidogrel response in feline patients.
Introduction:
Cats with cardiomyopathy face an increased risk of arterial thromboembolism (ATE). Although clopidogrel is frequently utilized to mitigate this risk, feline responses to this therapy exhibit variability. This study evaluated 2 viscoelastic devices, thromboelastography (TEG) and Viscoelastic Coagulation Monitor (VCM), for monitoring clopidogrel in cats in comparison to light transmission aggregometry (LTA).
Methods:
Twenty-eight healthy cats received clopidogrel for 7 days. Blood was collected at baseline and after treatment for analysis by TEG, VCM, and LTA.
Results:
On LTA, maximum amplitude, slope, and area under the curve (AUC) significantly decreased after treatment (p < 0.0001). On VCM, maximum clot firmness (MCF) significantly increased after treatment (p = 0.002). On TEG, R-time significantly prolonged (p = 0.024), while K and alpha angle significantly changed (p = 0.0002 and p = 0.0014, respectively). There was a moderate negative correlation between TEG R-time and LTA AUC (r = -0.39, p = 0.042). Eight cats were identified as non-responders to clopidogrel. Of the 8 non-responders, 6 (75%) had shortened R time after treatment. VCM appeared to be less discriminatory in identifying non-responders.
Discussion:
LTA remained the gold standard of monitoring clopidogrel treatment in cats. Unexpected changes on VCM and TEG were likely related to high interindividual and assay variability and increased sensitivity of feline platelets. R-time on TEG may have potential utility for point-of-care monitoring of clopidogrel response in cats.
