1. Platelet Function Testing: Which one Should we Perform and
how to Interpret the Data?
Dominick J. Angiolillo, MD, PhD, FACC, FESC, FSCAI
Director of Cardiovascular Research
Assistant Professor of Medicine

2. Dominick J. Angiolillo, MD, PhD
DISCLOSURES
Dominick J. Angiolillo, MD, PhD
Within the past 12 months, the presenter or their spouse/partner have had a financial interest/arrangement or affiliation with the organization listed below.
Honoraria/Lectures: Bristol Myers Squibb, Sanofi-Aventis, Eli Lilly Co, Daiichi Sankyo, Inc.,
Advisory Board: Bristol Myers Squibb, Sanofi-Aventis, Eli Lilly Co, Daiichi Sankyo, Inc., The Medicines Company, Portola Pharmaceuticals, Novartis, Arena Pharmaceuticals, Accumetrics, Medicure
Research Grants: GlaxoSmithKline, Otsuka, Accumetrics, Eli Lilly Co, Daiichi Sankyo, Inc., The Medicines Company, Portola Pharmaceuticals, Schering-Plough, Astra Zeneca, Johnson & Johnson
I intend to reference unlabeled/ unapproved uses of drugs or devices in my presentation.
I intend to reference Ticagrelor, Elinogrel, Cangrelor, and TRA.

3. Antiplatelet Drug Resistance / Response Variability:
An Emerging Clinical Problem

4. Platelet Function Tests
Platelet Aggregation
Light transmittance aggregometry (LTA)
Impedance platelet aggregation
Flow Cytometry
GPIIb/IIIa receptor activation
P-selectin expression
Monocyte-platelet aggregates
Vasodilator-associated stimulated phosphoprotein (VASP)
Point-of-care
Ultegra rapid platelet function analyzer (VerifyNow)
Thromboelastagraph (TEG)
PFA-100
Plateletworks
Cone and plate(let) analyzer (IMPACT)
Genetic testing
gold standard
adapted from Angiolillo DJ et al. J Am Coll Cardiol. 2007

5. Definitions of Non/Low – Response using LTA
Gurbel PA et al.,
Circulation 2003
Müller I et al.,
Thromb Haemostas 2003
Matetzky S et al.,
Circulation 2004
Serebruany VL et al.,
J Am Coll Cardiol 2005
Angiolillo DJ et al.,
Thromb Res 2005
Absolute change in platelet aggregation from baseline < 10%
Relative change in platelet aggregation from baseline < 10%
Lowest quartile of relative reduction of platelet aggregation
Platelet aggregation 2 standard deviations below mean
Relative change in platelet aggregation from baseline < 40%
(Variable results also depending on the concentration of ADP used)

6. A B Definitions of Non-Response: Which one should we use?
Absolute Change or Relative Change?
Absolute Change or Relative Change or Post-treatment platelet reactivity? A B
31%
(80 – 55) X 100% 80 =
18%
(50 – 41) X 100% 50
Responder
Low-Responder
+ Treatment (Post) 55
Baseline (Pre) 80
+ Treatment (Post) 41
Baseline (Pre)
25% 9%
Responder
Non-Responder
%Transmittance 50
%Transmittance 50
100
100
Time (minutes)
Time (minutes)

7. Individual Response Variability to Dual Antiplatelet Therapy in the Steady State Phase of Treatment20 15
Bleeding risk
Ischemic risk
Number of Patients 10 5
2.5
12.5
22.5
32.5
42.5
52.5
62.5
72.5
82.5
92.5
7.5
17.5
27.5
37.5
47.5
57.5
67.5
77.5
87.5
97.5
% Platelet Aggregation (LTA-ADP 20mmol/L)
Adapted from Angiolillo DJ et al. Am J Cardiol. 2006;97:38-43.

8. Optimizing Platelet Response in Suboptimal Responders
Modifying dosage of currently approved drugs
(e.g. higher dose)
Adding other agents with antiplatelet properties
(e.g. GPIIb/IIIa inhibitors; cilostazol)
Using alternative drugs
(e.g. ticlopidine or novel antiplatelet agents)

9. VASP Guided PCI
After a 600mg clopidogrel LD, poor responders (PRI ≥ 50%) received additional 600mg bolus (max 2400 mg) until reaching therapeutic target.
Mean ±SD
Control
VASP-guided p
VASP after first LD, %
68 ±11
69 ±10
0.4
VASP after adjustment, % 
38 ±14*
*<0.001
Log rank p =0.007
MACE: CV death, MI, revascularization
Bonello et al. J Am Coll Cardiol 2008

10. VASP and LTA: limitations
Not-user friendly
Time consuming
Require experienced lab personnel
Require expensive equipment
Not universally available
Overall,….expensive

11. Fibrinogen-coated beads Agglutinated beads aggregate in clusters
How does the VerifyNow Assay Work?
Whole blood, closed-tube sampling with no pipetting required
Assay results in less than 5 minutes (assay time)
Good correlation with LTA and VASP
Light
Source
Platelets in whole blood maximally activated by agonist in mixing chamber
Fibrinogen-coated beads +
Agonist
Agglutinated beads aggregate in clusters
Mixing
Chamber
Agonists:
Aspirin Assay – AA
P2Y12 assay – ADP + PGE1
GpIIbIIIa assay – iso-TRAP

12. Results are based on the rate and extent of platelet aggregation and are reported in P2Y12 Reaction Units (PRU) and % platelet inhibition
Results are reported as PRU
Results are also reported as % platelet inhibition

13. Primary Endpoint Tp >3ULN w/in 48 hs
Tailoring Treatment with Tirofiban in patients showing Resistance to aspirin and/or Resistance to clopidogrel
Patients with stable, unstable low risk CAD undergoing elective PCI being ASA and/or clopidogrel resistance using Verify Now
Primary Endpoint Tp >3ULN w/in 48 hs
P=0.009 for superiority 50
RRR: 42% 95%CI: 61-12 45 40
35.1%
Placebo 35
Tirofiban 30 25
20.4% 20 15 10 5
Valgimigli M et al Circulation 2009; 119:

14. Platelet inhibition (%)
OPTIMUS (Optimizing Antiplatelet Therapy in Diabetes Mellitus) Impact of high clopidogrel maintenance dosing on platelet function in DM patients with suboptimal clopidogrel response
VerifyNow P2Y12 substudy
%IPA
PRU 20 40 60 80
75 mg
150 mg
Platelet inhibition (%)
p=0.009
P2Y12 Reactivity Units 50
100
150
200
250
300
p=0.007
Angiolillo DJ et al. Circulation. 2007;115:
Angiolillo DJ et al. Am J Cardiol. 2008;101:440-5.

15. G R A V T A S
Successful PCI with DES without major complication or GPIIb/IIIa use
VerifyNow P2Y12 Assay hours post-PCI
PRU ≥ 230?
Yes No
Responder
Non-Responder
Random Selection R
ACS A B C
N = 1100
N = 1100
N = 583
“Tailored Therapy”
clopidogrel 600-mg*, then
clopidogrel 150-mg/day
“Standard Therapy”
placebo loading dose, then clopidogrel 75mg +placebo/day
“Standard Therapy”
placebo loading dose clopidogrel 75mg +placebo/day
Clinical Follow-up And Platelet Function Assessment at 30 days, 6M
Primary Endpoint: 6 month CV Death, Non-Fatal MI, ARC definite/prob ST
Safety Endpoint: GUSTO Moderate or Severe Bleeding
Cost-Effectiveness Analysis
Price MJ, Berger PB, Angiolillo DJ, et al. Am Heart J 2009

16. TRIGGER-PCI
Courtesy of F.J. Neumann
Successful PCI with DES without major complication and NO GPIIb/IIIa use
Post-PCI VerifyNow P2Y12 Assay (PRU) hours after 1st MD of clopidogrel 75 mg at day 1 post-PCI
N ~ 8800
Yes
PRU ≥ 208? No
Non-Responder
Responder
PRU ≥ 140?
Random Selection A B C D E
N = 1075
N = 1075
N = 550
N = 550
“Prasugrel arm”
Prasugrel 60 mg LD
Prasugrel 10 mg MD
+ Clopidogrel placebo
“Clopidogrel arm”
Placebo LD
Clopidogrel 75 mg MD
+ Prasugrel placebo
“Prasugrel arm”
Prasugrel 60 mg LD
Prasugrel 10 mg MD
+ Clopidogrel placebo
“Clopidogrel arm”
Placebo LD
Clopidogrel 75 mg MD
+ Prasugrel placebo
“Standard Therapy”
Clopidogrel 75 mg
Neumann
Platelet function substudy:
VerifyNow Assessment at day 2 (2 – 4 h after 1st MD of study drug)
Clinical Follow-up and VerifyNow Assessment at 90 days, 180 days
Primary Endpoint: 6 month CV Death and MI 16

17. Platelet Stimuli Platelet Aggregation AA COX-1 TxA2 TxA2 Collagen
Shear rate
P2Y12 ADP
Thrombin
Anti-II (gatrans)
Anti X (xabans)
Serotonin
Thrombin
Epinephrine
PAR-1 antagonists
E5555
SCH AA
COX-1
TxA2
TxA2
TX inhibitors
Ridogrel
NCX-4016
S18886
GP IIb/IIIa integrin
Platelet Aggregation

18. (oral ingestion of pro-drug)
Pharmacogenetics of Cardiovascular Antithrombotic Therapy N S O Cl
CH3 C
Clopidogrel
(oral ingestion of pro-drug)
MDR-1
Platelet membrane receptors
P2Y12 , GP IIb/IIIa, GP Ia
Genetic targets
CYP enzyme system
Two sequential steps:
One step: CYP3A4, CYP3A5, CYP2C9, CYP1A2
Both steps: CYP2B6, CYP2C19
Intestinal absorption
Hepatic generation
of active metabolite
HOOC
* HS N O Cl
OCH3
Platelet inhibition
Marin F & Angiolillo DJ. J Am Coll Cardiol 2009 ;54:

19. Intermediate phenotypes: PD/ PK
Balancing Safety and Efficacy
Inhibition of platelet aggregation
High risk of
ischemic events
bleeding events
Risk of any event
“Sweet spot”
Phenotypes: DM, ACS, CKD
Intermediate phenotypes: PD/ PK
Genotypes
Ischemic risk
Bleeding risk
Ferreiro & Angiolillo. Thromb Haemost 2010 (in press)

20. Need for “individualized” treatment!
Does one size fit all??
Need for “individualized” treatment!