The Effect on Blood Cells, Known as Platelets, Using Prasugrel vs Clopidogrel in Patients With the Heart Problem Acute Coronary Syndrome (ACS)

Inhibition of Residual Platelet Aggregation (IRPA) to 5 μM ADP

IRPA is calculated as a percent decrease of RPA from baseline using the following formula: (\[RPA at baseline - RPA at time of postbaseline\] / RPA at baseline) x 100%

Time frame: 14 days after maintenance dose (MD)

Platelet Reactivity Index (PRI)

Platelet Reactivity Index percentage was assessed by Vasodilator-stimulated phosphoprotein (VASP). PRI percent (%) was calculated using the median fluorescence intensity (MFI) of samples included with prostaglandin E1 (PGE1) and ADP, according to the following formula: PRI%=\[(MFI(PGE1)-MFI(PGE1 + ADP)/MFI(PGE1)\]x100 Lower PRI% values indicate greater P2Y12 receptor blockade.

Time frame: 14 days after maintenance dose (MD)

P2Y12 Reaction Units (PRU)

P2Y12 Reaction Units (PRU) assessed by Accumetrics Verify NowTM P2Y12. PRU represents the rate and extent of adenosine (ADP)-stimulated platelet aggregation. Lower values indicate greater P2Y12 platelet inhibition.

Time frame: 14 days after maintenance dose (MD)

Poor Responder of MPA to 20 μM ADP Following Maintenance Dose (MD)

Poor responder is defined as MPA to 20 μM ADP \>75th percentile of the value at 6-18 hours post-clopidogrel LD.

Time frame: 14 days after maintenance dose (MD)

Change in MPA to 20 μM ADP From Baseline to 6-18 Hrs Post Loading Dose (LD)

Maximum platelet aggregation to 20 μM ADP was assessed by LTA.

Time frame: Baseline to 6-18 hrs post loading dose (LD)

Change in MPA to 20 μM ADP From 6-18 Hrs Post Loading Dose (LD) to 14 Days After the First Maintenance Dose (MD)

Maximum platelet aggregation to 20 μM ADP was assessed by LTA.

Time frame: 6-18 hrs post loading dose (LD) to 14 days after the first maintenance dose (MD)

MPA to 20 μM ADP at 14 Days After the First Maintenance Dose (MD)

Maximum platelet aggregation to 20 μM ADP was assessed by LTA.

Time frame: 14 days after the first maintenance dose (MD)

MPA to 20 μM ADP at 14 Days After the Second Maintenance Dose (MD)

Maximum platelet aggregation to 20 μM ADP was assessed by LTA.

Time frame: 14 days after the second maintenance dose (MD)

Number of Participants With Bleeding Events According to Thrombolysis in Myocardial Infarction Study Group (TIMI) Criteria

Bleeding events will be classified as Major Bleeding, Minor Bleeding, or Insignificant Bleeding according to the TIMI criteria. Major bleeding: any intracranial hemorrhage (ICH) OR any clinically overt bleeding (including bleeding evident on imaging studies) associated with a fall in hemoglobin (Hgb) of ≥5 gm/dL from baseline. Minor Bleeding: any clinically overt bleeding associated with a fall in Hgb of ≥3 grams/deciliter (gm/dL) but \<5 gm/dL from baseline. Insignificant bleeding: any bleeding event that does not meet criteria for a Major or Minor bleed.

Time frame: 14 days after maintenance dose (MD)

Number of Participants With Bleeding Events According to Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO)

Bleeding events will be classified according to the GUSTO definitions as follows: Severe or Life-Threatening Bleeding: any ICH OR any bleeding event resulting in substantial hemodynamic compromise requiring treatment. Moderate Bleeding: any bleeding event resulting in the need for transfusion. Minor bleeding: any other bleeding event that does not require transfusion or cause hemodynamic compromise.

Time frame: 14 days after maintenance dose (MD)

Correlation of MPA to 20 μM ADP and PRU

Pearson-correlation estimated between MPA to 20 μM ADP and Accumetrics VerifyNowTM P2Y12 PRU

Time frame: Baseline through 29 days of treatment