***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background — Data from r and omized trials has demonstrated the superiority of bivalirudin to glycoprotein IIb/IIIa inhibitors plus heparin in patients undergoing primary percutaneous coronary intervention . Real-world performance of bivalirudin in primary percutaneous coronary intervention and the benefit of bivalirudin over heparin remain unknown in an era of routine dual antiplatelet therapy . Methods and Results —From July 2004 to December 2010 , 2317 consecutive patients were indexed in the University of Ottawa Heart Institute ST-segment – elevation myocardial infa rct ion registry . During this period 748 patients received bivalirudin , 699 patients received glycoprotein IIb/IIIa inhibitors , and 676 patients received unfractionated heparin alone .  The primary outcome was the rate of noncoronary artery bypass graft related thrombolysis in myocardial infa rct ion major bleeding .  Bivalirudin significantly reduced the primary outcome compared with heparin plus glycoprotein IIb/IIIa inhibitors ( 2.7 % versus 7.3 % , adjusted OR 2.96 , 95 % CI : 1.61–5.45 , P<0.001 ) and the composite end point of death , stroke , reinfa rct ion and major bleed ( OR 1.66 , 95 % CI : 1.12–2.45 , P=0.01 ) . Compared with heparin alone , a reduction in major bleeds ( OR 1.21 , 95 % CI : 0.60–2.44 , P=0.59 ) or the composite end point ( 1.05 , 95 % CI : 0.68–1.63 , P=0.83 ) with bivalirudin could not be demonstrated . Notably , major bleeding was associated with a 5-fold increase in the risk of mortality both in-hospital ( 3.5 % versus 20.6 % ) and out to 180 days ( 5.6 % versus 25.8 % ) . Conclusions —Bivalirudin use compared with glycoprotein IIb/IIIa inhibitors plus heparin as an antithrombotic strategy in primary percutaneous coronary intervention results in less major bleeding in contemporary practice . A benefit of bivalirudin over heparin could not be established with this registry and requires additional investigations to either confirm or refute Background Clopidogrel is administered to prevent stent thrombosis ; however , the uniformity of platelet inhibition after treatment and the influence of pretreatment reactivity on drug response have not been described . Methods and Results Platelet aggregation ( 5 and 20 μmol/L ADP ) , the activation of glycoprotein IIb/IIIa ( PAC‐1 antibody ) , and the expression of P‐selectin were measured in patients undergoing elective coronary stenting ( n=96 ) at baseline and at 2 hours , 24 hours , 5 days , and 30 days after stenting . All patients received aspirin ( 325 mg ) . Clopidogrel ( 300 mg ) was administered in the catheterization laboratory and followed by 75 mg daily . There was marked interindividual variability in drug response as measured by all markers that showed a normal distribution . Resistance , defined as baseline aggregation ( % ) minus posttreatment aggregation ( % ) ≤10 % by 5 μmol/L ADP , was present in 31 % and 15 % of patients at 5 and 30 days , respectively . Patients with the highest pretreatment platelet reactivity remained the most reactive at 24 hours after treatment ( P<0.0001 ) . Conclusions Interindividual variability in the platelet inhibitory response  from clopidogrel occurs in patients undergoing elective coronary stenting . Patients with high pretreatment reactivity are least protected . Alternative pharmacological strategies and the association of adverse ischemic events should be investigated in these patients . ( Circulation . 2003 ; 107:2908‐2913 . Current guidelines suggest that patients undergoing percutaneous coronary intervention ( PCI ) receive dual-antiplatelet therapy . There are limited data on the pharmacodynamics of P2Y12 inhibitors in patients with cardiac arrest and return of spontaneous circulation ( ROSC ) undergoing PCI and therapeutic hypothermia ( TH ) . Accordingly , we compared inhibition of platelet reactivity in patients undergoing TH receiving clopidogrel or ticagrelor . Notably , clopidogrel was ineffective in lowering platelet reactivity , with ticagrelor providing a more rapid ( within 4 hours ) and sustained reduction ( 6 days ) in platelet reactivity . Pending outcome -based studies , ticagrelor should be used preferentially in patients who have ROSC and are undergoing PCI and TH Platelet reactivity ( PR ) and bleeding events following therapy with ticagrelor vs prasugrel have not been adequately studied . We aim ed to compare PR and bleeding events in patients with acute coronary syndrome ( ACS ) undergoing percutaneous coronary intervention ( PCI ) while on ticagrelor vs prasugrel for one month . Consecutive patients who were discharged either on ticagrelor 90 mg bid maintenance dose ( MD ) or prasugrel 10 mg MD were invited for PR assessment ( VerifyNow , in PRU ) at one month . High PR ( HPR ) was defined as > 208 PRU . Bleeding events [ Bleeding Academic Research Consortium ( BARC ) classification ] were monitored . Out of 937 screened patients , 512 were analysed , 278 under ticagrelor MD and 234 under prasugrel MD .  PR at 30 days ( C-statistic of the propensity score model 0.63 , 0.58 - 0.67 95 % CI , p<0.001 ) was lower when on ticagrelor compared with prasugrel ( 33.3 , 95 % CI 29.3 - 37.3 vs 84.6 , 95 % CI 73.6 - 95.6 , p<0.001 ) . In the analysed population more BARC type 1 bleeding events were observed with ticagrelor compared to prasugrel ( 36.7 % vs 28.2 % , p=0.047 ) . In 221 propensity score matched pairs , BARC type 1 bleeding rate was marginally higher in ticagrelor vs prasugrel treated patients ( 35.7 % vs 27.1 % , p=0.05 ) . BARC type ≥2 events did not differ between groups 5 ( 2.3 % ) vs 5 ( 2.3 % ) . HPR rate was higher for prasugrel-treated patients ( 5.4 % vs 0 % , p<0.001 ) . In conclusion , in patients with ACS undergoing PCI , ticagrelor MD produces a significantly higher platelet inhibition compared to prasugrel MD . This pharmacodynamic difference might be associated with more nuisance bleeding events with ticagrelor use OBJECTIVES The objective was to evaluate the pharmacodynamic response of switching patients on maintenance phase clopidogrel therapy after an acute coronary syndrome ( ACS ) to prasugrel . BACKGROUND Prasugrel P2Y(12 ) receptor blockade is associated with greater pharmacodynamic platelet inhibition and reduction of ischemic complications compared with that of clopidogrel in ACS patients undergoing percutaneous coronary intervention . The pharmacodynamic effects of switching patients during maintenance phase clopidogrel therapy after an ACS event to prasugrel are unknown . METHODS The SWAP ( SWitching Anti Platelet ) study was a phase 2 , multicenter , r and omized , double-blind , double-dummy , active-control trial . After a run-in of daily open-label clopidogrel 75 mg with aspirin therapy for 10 to 14 days , patients were r and omly assigned to 1 of the following 3 treatments : placebo loading dose (LD)/clopidogrel 75 mg maintenance dose ( MD ) , placebo LD/prasugrel 10 mg MD , or prasugrel 60 mg LD/10 mg MD . Platelet function was evaluated at 2 h , 24 h , 7 days , and 14 days using light transmittance aggregometry , VerifyNow P2Y(12 ) assay , and vasodilator-stimulated phosphoprotein phosphorylation . RESULTS A total of 139 patients were r and omized , of whom 100 were eligible for analysis .  Maximum adenosine diphosphate-induced platelet aggregation ( 20 μM ) by light transmittance aggregometry at 1 week ( primary end point ) was lower after prasugrel MD compared with clopidogrel MD ( 41.1 % vs. 55.0 % , p < 0.0001 ) , and was also lower in the prasugrel LD+MD group compared with clopidogrel MD ( 41.0 % vs. 55.0 % , p < 0.0001 ) . At 2 h , a prasugrel LD result ed in higher platelet inhibition compared with the other regimens . Similar results were found using light transmittance aggregometry with 5 μM adenosine diphosphate , VerifyNow P2Y(12 ) , and vasodilator-stimulated phosphoprotein phosphorylation assays . CONCLUSIONS For patients receiving maintenance clopidogrel therapy after an ACS event , switching from clopidogrel to prasugrel is associated with a further reduction in platelet function by 1 week using prasugrel MD or within 2 h with the administration of a prasugrel LD . ( A Pharmacodynamic Comparison of Prasugrel [ LY640315 ] Versus Clopidogrel in Subjects With Acute Coronary Syndrome Who Are Receiving Clopidogrel [ SWAP ] ; NCT00356135 ) Background —Although r and omized clinical trials have compared clopidogrel with higher potency ADP receptor inhibitors ( ADPris ) among patients with myocardial infa rct ion , little is known about the frequency and factors associated with switching between ADPris in clinical practice . Methods and Results —We studied 47 040 patients with myocardial infa rct ion treated with percutaneous coronary intervention , who received either clopidogrel or prasugrel within 24 hours of admission at 361 US hospitals from July 2009 to June 2011 using the merged Acute Coronary Treatment and Intervention Outcomes Network Registry – Get With the Guidelines and CathPCI Registry data base . Hierarchical logistic regression modeling was used to determine factors independently associated with in-hospital ADPri switching . Among 40 531 patients treated initially in-hospital with clopidogrel , 2125 ( 5.2 % ) were discharged on prasugrel ; this frequency steadily increased from 0 % to 7 % during the study period . Among 6509 patients treated initially in-hospital with prasugrel  , 751 ( 11.5 % ) were discharged on clopidogrel . The frequency of this switch increased from 6 % to 18 % during the first 2 quarters of the study period and decreased to 9 % by the end . Switching clopidogrel to prasugrel was associated with high-risk angiographic characteristics ( thrombotic , long , and bifurcating lesions ) , reinfa rct ion in-hospital , and private health insurance coverage . Older age , previous cerebrovascular event , in-hospital coronary artery bypass grafting , in-hospital bleeding , and warfarin use at discharge were associated with switching prasugrel to clopidogrel . Conclusions —Clopidogrel and prasugrel are not uncommonly switched in-hospital in patients with myocardial infa rct ion undergoing percutaneous coronary intervention . In contemporary US practice , in addition to risk for bleeding and recurrent ischemic events , medical drug coverage is a major determinant of ADPri selection Background — The increasing use of higher-than-approved doses of clopidogrel in clinical practice is based in part on the desire for greater levels of inhibition of platelet aggregation ( IPA ) .  Prasugrel is a new thienopyridine that is more potent than st and ard-dose clopidogrel in healthy subjects and patients with stable coronary artery disease . The relative antiplatelet effects of prasugrel versus high-dose clopidogrel in percutaneous coronary intervention patients are unknown . Methods and Results — Prasugrel in Comparison to Clopidogrel for Inhibition of Platelet Activation and Aggregation – Thrombolysis in Myocardial Infa rct ion 44 ( PRINCIPLE-TIMI 44 ) was a r and omized , double-blind , 2-phase crossover study of prasugrel compared with high-dose clopidogrel in patients undergoing cardiac catheterization for planned percutaneous coronary intervention . The primary end point of the loading-dose phase ( prasugrel 60 mg versus clopidogrel 600 mg ) was IPA with 20 & mgr;mol/L ADP at 6 hours . Patients with percutaneous coronary intervention entered the maintenance-dose phase , a 28-day crossover comparison of prasugrel 10 mg/d versus clopidogrel 150 mg/d with a primary end point of 
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Conclusions The current study suggests that switching to a novel P2Y12 agent in patients with ACS and /or patients undergoing coronary stenting is more efficacious than continuing clopidogrel .
In this cohort , switching to a novel agent did not result in worse ischemic outcomes than upfront initiation of novel therapies .
However , switching was associated with greater bleeding compared with both continued clopidogrel as well as upfront use of novel P2Y12 agents