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Updated: Jul 19, 2026
Microfluidics in Assessing Platelet Function
Published on: November 8, 2024
Quantifying the effect of antiplatelet therapy: a comparison of the platelet function analyzer (PFA-100) and modified
Seema Agarwal1, Margaret Coakley, Margaret Coakely
1University Hospital of Wales, Cardiff, Wales, UK.
Insights
The modified thromboelastograph effectively monitors aspirin and clopidogrel
Area of Science:
- Cardiovascular Medicine
- Pharmacology
- Surgical Anesthesia
Background:
- Patients on aspirin and clopidogrel therapy present challenges for surgery due to increased bleeding risk.
- Identifying patients with heightened antiplatelet response is crucial for perioperative management.
- Perioperative blood loss can be significant in patients undergoing surgery while on antiplatelet medications.
Purpose of the Study:
- To evaluate point-of-care monitors for assessing antiplatelet effects of aspirin and clopidogrel.
- To compare the efficacy of the platelet function analyzer and modified thromboelastograph against aggregometry.
- To determine the utility of these monitors in predicting perioperative bleeding.
Main Methods:
- Assessed antiplatelet effects using the platelet function analyzer (PFA-100) and modified thromboelastograph (mTEG).
- Compared results with optical light transmission aggregometry.
- Evaluated 20 patients on aspirin and an unspecified number on clopidogrel.
Main Results:
- Modified thromboelastography identified 90% of aspirin responders, while PFA-100 identified 70%.
- Aggregometry showed a 50% response rate to clopidogrel, with mTEG identifying 70% of these responders.
- PFA-100 failed to identify any clopidogrel responders; mTEG showed good agreement with aggregometry for clopidogrel (kappa = 0.81).
Conclusions:
- The modified thromboelastograph is a viable point-of-care tool for monitoring aspirin and clopidogrel therapy.
- mTEG shows potential for monitoring antiplatelet therapy effectiveness and predicting perioperative bleeding risk.
- Further research is needed to establish mTEG as a standard for perioperative antiplatelet monitoring.
Background:
Antiplatelet therapy with aspirin and clopidogrel is known to confer protection against ischemic events. Increasing numbers of patients are presenting for surgery while taking these drugs. This may lead to an increase in perioperative blood loss, particularly in those who have a heightened response to the drugs. Identifying these patients preoperatively would allow us to plan appropriate management.
Methods:
The antiplatelet effect of aspirin and/or clopidogrel was measured using two point-of-care monitors: the platelet function analyzer (PFA-100; Dade, Miami, FL) and the modified thromboelastograph (mTEG; Haemoscope Corp., Niles, IL). This was compared with optical light transmission aggregometry.
Results:
All people taking aspirin displayed a definitive aspirin effect on aggregometry (n = 20). Ninety percent of these were identified by modified thromboelastography (n = 18). Seventy percent were identified by the platelet function analyzer (n = 14). Fifty percent of people taking clopidogrel displayed a definitive response to the drug on aggregometry. Seventy percent of these were identified on modified thromboelastography (n = 7). None were identified by the platelet function analyzer. There was good agreement between the results of the aggregometry and modified thromboelastography in clopidogrel patients (kappa = 0.81).
Conclusion:
The search for a point-of-care monitor of platelet function has been the focus of much research. This study has shown that the modified thromboelastograph can be used for monitoring the effect of clopidogrel as well as aspirin. It potentially has a wide scope to be used for the monitoring of effectiveness of therapy as well as a possible predictor of perioperative bleeding.
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