Resistance to antiplatelet drugs is frequently found in clinical practice, however clinical relationships are at the time being still mostly elusive
Normally, we used different agonist to trigger platelet aggregation, which could be measured through the maximum curve height above baseline. Agonists include ADP, Collagen, Thrombin.......each agonist has its response receptor on platelet. I.E. ADP-P2Y, Collagen-GPVI, Thrombin-PAR......Thus the aggregation of each agonist reflect its receptor's function. Hope that it is heplful for you....
Dear Chaojun Tang, thanks it is helpful, although I was thinking more on the factors that challange reproducibility of tests. As for instance diabetes is known to increase number of positive test results and those are not in straight forward correlation with increased prevalence of clincial endpoints as trhombotic event.
Yes, it was further informative, although the field is still at the time being somewhat perplexed, Thanks Jacek Splawinski, best regards.
Thrombin is among the strongest platelet activators. Therefore, any compound that favours plasmatic thrombin generation (e.g. the oligo-delta-negative molecule glucose) will have an impact on platelet aggregation. To check this you should also perform an innovative thrombin generation test (e.g. the RECA).
If you are concerned about antiplatelet drug resistance, a proven variable is the activity and expression level of drug metabolizing enzymes such as the cytochrome oxidases. For example, resistance to clopidogrel has been shown in some patients to be mediated by polymorphisms in cytochrome P450. There other examples as well, but we are probably at the beginning of understanding patient-specific phenotypes.
I agree with the above given answers in terms of platelet aggregation pathways.
For perioperative platelet testing we use the Multiplate analyzer (multiple electrode aggregometry - MEA). The are good data on the prediction of bleeding tendencies when aggregation response is low on the one hand and on the other hand, that high responses correlate with in stent thrombosis. It also gives you the possibility to distinguish between drug responders and non-responders. Furthermore, coagulation management according to results of MEA (in adition to other point-of-care devices) is effective in saving allogenic blood products.
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