Basic Clinician Training Module 7 PlateletMapping™ PlateletMapping™ Assays

PlateletMapping™ What is it? Special TEG assay to measure effects of anti-platelet drug therapy on platelet function  Measure reduction in platelet function (MA) due to anti-platelet drugs  Provides individual’s potential total platelet function as a reference point  Identifies resistance or subtherapeutic response to drug therapy

ADP receptor inhibitors such as clopidogrel and ticlopidine Arachadonic acid pathway inhibitors such as aspirin GPIIb/IIIa inhibitors such as abciximab, tirofiban, eptifibatide PlateletMapping™ What drugs are monitored?

Individual response to anti-platelet drugs determine clinical outcome Knowing percent platelet inhibition is insufficient to determine therapeutic efficacy Also require knowledge of total or potential platelet function as a reference point Why PlateletMapping? Personalized platelet therapy

Patient A: 50% platelet inhibition is insufficient to completely reduce the risk of a thrombotic or ischemic event Patient B: 50% platelet inhibition provides anti- thombotic protection Patient C: 50% platelet inhibition increases risk of bleeding Why PlateletMapping? Personalized platelet therapy

The hemostatic process The end result of hemostasis is a 3-D network of fibrin and platelets linked by fibrinogen via the GPIIb/IIIa receptor The integrity of the fibrin-platelet network is expressed as the MA on the TEG analyzer.

The hemostatic process Hemostasis is a tightly regulated process consisting of three separate, but interrelated, steps:  Platelet plug formation = primary hemostasis  Fibrin clot formation  Fibrinolysis Interruption of platelet plug formation is a common therapeutic strategy to reduce risk of ischemic events (arterial thrombosis)

Anti-thrombotic strategies Inhibit platelet aggregation response Inhibit platelet activation – ADP receptor inhibitors (e.g. clopidogrel) Inhibit platelet secretion – block synthesis and secretion of TxA 2, a potent platelet activator (e.g. aspirin) Inhibit platelet aggregation – inhibit GPIIb/IIIa receptors (e.g. abciximab, tirofiban, eptifibatide)

PlateletMapping How it works - platelets ADP and TxA 2 both mediate activation/expression of GPIIb/IIIa receptors  aggregation ADP Inhibited by clopidogrel, ticlopidine TxA 2 Inhibited by aspirin

PlateletMapping How it works - platelets Activation/expression of GPIIb/IIIa receptors on platelet surface  platelet aggregation via interaction with fibrinogen Inhibited by abciximab, tirofiban, eptifibatide

PlateletMapping How it works - platelets ADP & TxA2 sites can be activated, but if the GPIIb/IIIa receptor is inhibited, platelet aggregation will not take place

PlateletMapping How it works - thrombin Most potent platelet agonist – overrides inhibition at other platelet activation pathways  Maximally activates platelets  Provides total platelet function during TEG analysis (MA) Cleaves fibrinogen to fibrin Converts Factor XIII to Factor XIIIa for fibrin cross linking

PlateletMapping How it works – the assay Channel 1: Thrombin-activated platelet function provides total platelet function (MA thrombin ), even in presence of anti-platelet agents Channels 2-4: Performed in presence of heparin to inhibit thrombin activity  Channel 2: Measures contribution of fibrin(ogen) to MA(MA fibrin ) by addition of ActivitorF which converts fibrinogen to fibrin and FXIII to FXIIIa  Channels 3 and 4: ADP or AA (arachadonic acid) + Activator F to measure platelet function and fibrin contribution to MA (MA ADP or MA AA ) Only non-inhibited platelets will be activated by ADP or AA Measures the reduction in platelet function due to anti- platelet agents

PlateletMapping assay At a glance

PlateletMapping assay Calculation of platelet inhibition % inhibition = [100 – (MA pi -MA f )/(MA t -MA f )] * 100 Where: MA pi = MA ADP or MA AA MA f = MA fibrin MA t = MA thrombin or MA KH

PlateletMapping assay TEG analysis - MA %Inhibition = 83.5

PlateletMapping assay TEG analysis – Clopidogrel resistance %Inhibition = 8.4

PlateletMapping assay TEG analysis – aspirin resistance MA THROMBIN MA AA MA FIBRIN %Inhibition = 0.0

Summary PlateletMapping measures platelet inhibition along with total platelet function as a reference point Monitors platelet inhibition at GPIIb/IIIa, ADP, and TxA 2 receptors Detects drug resistance as well as efficacy (i.e. inhibition) Provides for anti-platelet drug therapy personalized to patient’s hemostatic state.

Overview exercises PlateletMapping assay PlateletMapping results

#1 The MA parameter of TEG analysis demonstrates clot strength due to the contributions of ________ and ________. Answer Next

#2 Which of the following component of the PlateletMapping Assay allows for personalized anti-platelet therapy? a.Demonstrates percent platelet inhibition due to inhibitors of platelet activation b.Demonstrates percent platelet inhibition due to inhibitors of platelet aggregration c.Demonstrates total platelet function as a reference point Answer Next

B a.MA fibrin b.MA thrombin c.MA ADP d.MA AA Answer Next A 1.Demonstrates total platelet function 2.Demonstrates contribution of platelets and fibrin not inhibited by aspirin 3.Demonstrates contribution of fibrin 4.Demonstrates contribution of platelets and fibrin not inhibited by clopidogrel or ticlopidine: 5.Demonstrates contribution of platelets and fibrin not inhibited by GPIIb/IIIa inhibitors 6.Also known as MA KH #3 Match all the applicable descriptions in Column A to the appropriate PlateletMapping parameters in Column B

#4 Answer Next Although a 50% inhibition of platelet function was achieved with administration of an anti-platelet agent in each patient: Which patient is still at risk for an thromboembolic event? A, B or C? Which patient received optimal anti-platelet therapy? A, B, or C?

#5 Answer Next Each of the following patients were administered a standard dose of clopidogrel in the catherization laboratory. Based on the results of the PlateletMapping assay, which patient likely demonstrates resistance to the drug? A or B? A B

#6 The following PlateletMapping assay was performed on a patient prior to cardiac surgery (on pump, CABG) and 5 days after discontinuation of clopidogrel therapy. Is this patient at high or low risk for bleeding after surgery? Answer Next

End of Module 7

#1 The MA parameter of TEG analysis provides demonstrates clot strength due to the contributions of platelets and fibrin or fibrinogen. Next

#2 Which of the following component of the PlateletMapping Assay allows for personalized anti-platelet therapy? a.Demonstrates percent platelet inhibition due to inhibitors of platelet activation b.Demonstrates percent platelet inhibition due to inhibitors of platelet aggregration c.Demonstrates total platelet function as a reference point Next

B a.MA fibrin b.MA thrombin c.MA ADP d.MA AA Next A 1.Demonstrates total platelet function: b (MA thrombin ) 2.Demonstrates contribution of platelets and fibrin not inhibited by aspirin: d (MA AA ) 3.Demonstrates contribution of fibrin: a (MA fibrin ) 4.Demonstrates contribution of platelets and fibrin not inhibited by clopidogrel or ticlopidine: c (MA ADP ) 5.Demonstrates contribution of platelets and fibrin not inhibited by GPIIb/IIIa inhibitors: c,d (MA ADP, MA AA ) 6.Also known as MA KH : b (MA thrombin ) #3 Match all the applicable descriptions in Column A to the appropriate PlateletMapping parameters in Column B

#4 Next Although a 50% inhibition of platelet function was achieved with administration of an anti-platelet agent in each patient: Which patient is still at risk for an thromboembolic event? A, B or C? Which patient received optimal anti-platelet therapy? A, B, or C?

#5 Next Both of the following patients were administered a standard dose of clopidogrel in the catherization laboratory. Based on the results of the PlateletMapping assay, which patient likely demonstrates resistance to the drug? A or B? A B

#6 The following PlateletMapping assay was performed on a patient prior to cardiac surgery (on pump, CABG) and 5 days after discontinuation of clopidogrel therapy. Is this patient at high or low risk for bleeding after surgery? HIGH risk for bleeding due to a high level of platelet inhibition even after a 5 day period of not taking clopidogrel. Next