1. platelet function assays
PFA-100 – quick screen test, sensitive to VWD also
Light transmission platelet aggregometry on platelet-rich plasma (LTA)– platelet function evaluation, not suitable for antiplatelet therapy monitoring
Impedance whole blood aggregometry- good for antiplatelet therapy monitoring
TEG/PLTMAP – PLTMAP is designed for antiplatelet therapy monitoring

2. Which activation pathways are monitored for antiplatelet therapy

3. PFA-100

4. Occlusion of cartridge membrane aperture by platelet plug

5. a normal PFA-100 tracing (EPI cartridge)
Flow rate
Closure time induced by EPI

6. Falsely prolonged PFA-100 results
Low HCT
HCT is too low (< 35%). Plug tends to disassociate and causes “seesaw” tracing and prolonged closure time.
When platelet count is too low (< 100 K), closure time could be prolonged too.

7. TEG Tracing and Clotting Process Parameters

8. TRG Parameters
~80% contribution from activated platelets
~20% contribution from Fibrin
Not a reliable parameter since instrument couldn’t differentiate real clot lysis vs. artificial effect
Not sensitive to fibrinolysis

9. TEG example 1– question

10. TEG example 1 – answer

11. TEG example 2– question

12. TEG example 2 – answer

13. TEG example 3– question

14. TEG example 3 – answer

15. TEG example 4– question

16. TEG example 4 – answer

17. TEG example 5– question

18. TEG example 5 – answer

19. TEG example 6– question

20. TEG example 6 – answer

21. TEG example 7

22. Bleeding Patient with Normal TEG Tracing

23. TEG result example

24. TEG result comments
TEG is performed using both citrated whole blood and heparinase treated blood with commercially provided Kaolin. Results are reported as from CK (citrated whole blood + Kaolin activator) or CK/H (citrated whole blood + Kaolin activator + Heparinase) respectively. Results from CK and CK/H should be nearly the same if patient is not on heparin. When R is significantly prolonged due to heparin therapy, it could lead to decreased ANGLE and MA and increased K which doesn't accurately reflect patient's fibrinogen and platelet function.  The ANGLE and MA results from heparinase treated sample (CK/H) would be more suitable for reflecting patient's fibrinogen and platelet function in this case. TEG is NOT sensitive to Von Willebrand Disease and antiplatelet therapy. Normal results could be observed. DECREASED R: Shortened clotting time. May indicate hypercoaguable state or specimen activation. Clinical significance of shortened R interval is not well defined.   INCREASED R (CK) with NORMAL R (CK/H): Prolonged R corrected with heparinase, consistent with heparin effect.   INCREASED R (CK) with INCREASED R HEPARINASE (CK/H): Prolonged R, consistent with factor deficiency or anticoagulant effect such as Argatroban and Dabigatran.   INCREASED MA: Consistent with robust platelet/fibrinogen function.   INCREASED G: Consistent with robust platelet/fibrinogen function.   DECREASED MA: Consistent with decreased platelet/fibrinogen function or anticoagulated effect.   DECREASED G: Consistent with decreased platelet/fibrinogen function.   INCREASED K: Consistent with anticoagulant effect or factor deficiency.   DECREASED ANGLE: Consistent with Low Fibrinogen activity or anticoagulated effect.   DECREASED K: Consistent with elevated fibrinogen/platelet activity.   INCREASED ANGLE: Consistent with elevated fibrinogen/platelet activity.   INCREASED EPL: Consistent with increased fibrinolysis.

25. TEG tracing: Low FIB and Platelets
Angel: 8.8 normal range: 53 – 72
MA: normal range: 50 – 70
FIB: 35 mg/dL ↓ ↓
Platelet counts: 23K/uL ↓ ↓

26. PLTMAP tracing

27. PLTMAP is a personalized assay
based on patient’s own baseline platelet function

28. Inhibition % = 1 – Activation %
PLTMAP calculation formula
MA(TT)- MA(FIB) = Full potential of platelet activation
MA(ADP/AA) – MA(FIB) = Platelet activation by ADP /AA
Inhibition % = 1 – Activation %

29. PLTMAP result example

30. Whole blood impedance (WBIA) method
By Multiplate multichannel impedance aggregometer

31. how Multiplate cell works ?
Electrical resistance is enhanced by aggregation of platelets
on the sensor surface between the 2 sensor wires and reported as “area under curve” (AUC)

32. Multiplate – aggregation curve

33. ADP/AA assay on Multiplate aggregometer - protocol example
Per disposable test cell:
300 μl NaCL/CaCL2 or 0.9%NaCL
300 μl citrated donor blood
Incubation for 3 minutes
Addition of 20 μl ADP or 20 μl AA
 start test Monitoring for 6 minutes

34. Whole blood impedance (WBIA) method
By Multiplate multichannel impedance aggregometer
NOT a personalized assay
Compare with a wide normal range
Need consecutive tests:
Baseline (before antiplatelet therapy) important!
On antiplatelet drugs

35. WBIA Result example Result comments:
The multiplate assay impedance aggregometry method may be used to assess platelet function in patients who have received platelet-inhibiting drugs such as Aspirin, ADP receptor inhibitors(e.g. Clopidogrel, Prasugrel,Ticagrelor), or GP IIb-IIIa inhibitors (e.g. Abciximab, Tirofiban and Eptifibatide). The platelet aggregation response to platelet activation agonists ADP and arachidonic acid are reported as AUC (area under the curve). The AUC is directly proportional to platelet function and will decrease with platelet inhibitory drugs, platelet functional defects or thrombocytopenia. The clinical utility of this test in therapeutic decision-making has not been established. Therapeutic ranges have not been established for platelet inhibitor drugs with this assay. This test may be useful in assessing compliance or in assessing response in individual patients. Results may be affected by platelet count <150 K/uL.

36. Antiplatelet drug monitoring
Patient
Date
Multiplate AUC (impedance method)
Antiplatelet /antocoagulant therapy
ADP
nl( ) AA
nl ( ) EJ
10/16/
107
114
PLAVIX 1mg/kg started on 10/26/17;
Aspirin chew tab 81 mg twice a day started on 10/18/17
10/27/ 84 15
11/9/ 8 3
baseline
On Aspirin (DAY 9) and PLAVIX (DAY 1)
On Aspirin (DAY 21) and PLAVIX (DAY 13)
The results from Multiplates on these two patients correlated well with clinical anti-platelet drug therapy.

37. Multiplate AUC (impedance method) Antiplatelet /antocoagulant therapy
WBIA and LTA
Patient
Date
Multiplate AUC (impedance method)
PAP-8 (LTA method) %
Antiplatelet /antocoagulant therapy
ADP nl( )
AA nl ( )
ADP nl ( > 63)
AA nl ( > 74) YH
3/3/2016 15 7
42 disaggregated to 2 6
Plavix, ASA BK 80 91 98
>100
Heparin
The results from Multiplates on these two patients correlated well with the results obtained by PAP-8 (LTA method). It also correlated well with clinical anti-platelet drug therapy.

38. Multiplate AUC (impedance method) Platelet mapping (mechanical method)
WBIA, LTA and PLTMAP
Patient
Date
Multiplate AUC (impedance method)
PAP-8 (LTA method) %
Platelet mapping (mechanical method)
Antiplatelet Therapy
ADP nl( )
AA nl ( )
ADP nl ( > 63)
AA nl ( > 74)
ADP inhibition %
AA inhibition %
11/28/2016 12 5
N/A
93.3
99.6
Plavix, ASA
11/29/2016 67 56 75 73
none
The results from Multiplates on these two patients correlated well with the results obtained by PAP-8 (LTA method) and Platelet Mapping. It also correlated well with clinical anti-platelet drug therapy.