David Foley

Prasugrel 5 mg in the Very Elderly Attenuates Platelet Inhibition But Maintains Noninferiority to Prasugrel 10 mg in Nonelderly Patients : The GENERATIONS Trial, A Pharmacodynamic and Pharmacokinetic Study in Stable Coronary Artery Disease Patients

OBJECTIVESnThis study assessed pharmacodynamic (PD) response to the reduced prasugrel maintenance dose of 5 mg in very elderly (VE) patients (≥75 years of age).nnnBACKGROUNDnIn the TRITON-TIMI 38 (TRial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet InhibitioN with Prasugrel-Thrombolysis In Myocardial Infarction 38) study prasugrel 10 mg reduced ischemic events versus clopidogrel 75 mg, but increased bleeding in VE patients.nnnMETHODSnWe examined PD and active metabolite pharmacokinetics (PKs) with prasugrel 5 and 10 mg and clopidogrel 75 mg in a 3-period (12 days each) blinded, crossover study in VE (nxa0= 73; mean: 79 ± 3 years of age) or (nxa0= 82) nonelderly (NE) (≥45 toxa0<65 years of age; mean: 56 ± 5 years of age) stable coronary artery disease (CAD) patients receiving background aspirin. Assays included light transmission aggregometry (LTA), VerifyNow P2Y12 (VN-P2Y12), and vasodilator-associated stimulated phosphoprotein (VASP). The primary comparison was noninferiority of maximum platelet aggregation (MPA) comparing the median for prasugrel 5 mg in VE versus the 75th percentile for prasugrel 10 mg in NE, using a pre-specified 1-sided 97.5% confidence interval for the differencexa0<15%.nnnRESULTSnPrasugrel 5 mg in VE met the primary PD noninferiority criterion versus prasugrel 10 mg in NE. For prasugrel 5 mg, MPA was significantly lower (57 ± 14%) than clopidogrel (63 ± 14%; pxa0< 0.001) in VE but higher than prasugrel 10 mg in NE (46 ± 12%; pxa0< 0.001). PD response by LTA, VN-P2Y12, and VASP during all treatments appeared similar between age cohorts. Prasugrel 5 mg resulted in fewer VE poor responders than clopidogrel. Rates of mild bleeding were higher with prasugrel 10 mg but similar for prasugrel 5 mg versus clopidogrel 75 mg.nnnCONCLUSIONSnIn aspirin-treated stable CAD patients, prasugrel 5 mg in VE attenuated platelet inhibition while meeting pre-specified noninferiority criterion versus prasugrel 10 mg in NE, with significantly better PD response and fewer poor responders compared to clopidogrel 75 mg in VE. (Comparison of Prasugrel and Clopidogrel in Very Elderly and Non-Elderly Patients With Stable Coronary Artery Disease [GENERATIONS]; NCT01107912).

Efficacy and safety of left atrial appendage closure with WATCHMAN in patients with or without contraindication to oral anticoagulation: 1-Year follow-up outcome data of the EWOLUTION trial

BACKGROUNDnLeft atrial appendage (LAA) occlusion with WATCHMAN has emerged as viable alternative to vitamin K antagonists in randomized controlled trials.nnnOBJECTIVEnEWOLUTION was designed to provide data in routine practice from a prospective multicenter registry.nnnMETHODSnA total of 1025 patients scheduled for a WATCHMAN implant were prospectively and sequentially enrolled at 47 centers. Indication for LAA closure was based on European Society of Cardiology guidelines. Follow-up and transesophageal echocardiography (TEE) were performed per local practice.nnnRESULTSnThe baseline CHA2DS2-VASc score was 4.5 ± 1.6; the mean age was 73.4 ± 9 years; previous transient ischemic attack/ischemic stroke was present in 312 (30.5%), 155 (15.1%) had previous hemorrhagic stroke, and 320 (31.3%) had a history of major bleeding; and 750 (73%) were deemed unsuitable for oral anticoagulation therapy. WATCHMAN implant succeeded in 1005 (98.5%) of patients, without leaks >5 mm in 1002 (99.7%) with at least 1 TEE follow-up in 875 patients (87%). Antiplatelet therapy was used in 784 (83%), while vitamin K antagonists were used in only 75 (8%). At 1 year, mortality was 98 (9.8%), reflecting the advanced age and comorbidities in this population. Device thrombus was observed in 28 patients at routine TEE (3.7%) and was not correlated with the drug regimen (P = .14). Ischemic stroke rate was 1.1% (relative risk 84% vs estimated historical data); the major bleeding rate was 2.6% and was predominantly (2.3%) nonprocedure/device related.nnnCONCLUSIONnLAA closure with the WATCHMAN device has a high implant and sealing success. This method of stroke risk reduction appears to be safe and effective with an ischemic stroke rate as low as 1.1%, even though 73% of patients had a contraindication to and were not using oral anticoagulation.

Clopidogrel discontinuation and platelet reactivity following coronary stenting.

See also Lordkipanidzé M, Harrison P. Beware of being caught on the rebound. This issue, pp 21–3.

Dual antiplatelet therapy unmasks distinct platelet reactivity in patients with coronary artery disease.

Summary.u2002 Background: Platelet‐induced thrombosis is a major risk factor for recurrent ischemic events, although platelet function in patients with cardiovascular disease taking aspirin and clopidogrel is very poorly characterized. The aim of this study was to assess platelet reactivity in patients with cardiovascular disease taking aspirin and clopidogrel. Methods: We developed a rapid assay to measure platelet aggregation in response to arachidonic acid, collagen, adenosine diphosphate (ADP), epinephrine and thrombin receptor activating peptide (TRAP) in 80 healthy volunteers. We then recruited 200 consecutive patients from outpatient clinics and the cardiac catheterization laboratory and tested platelet function. Platelet aggregation induced by epinephrine is a marker of global platelet reactivity. We tested platelet function in 146 patients compliant with antiplatelet therapy. Platelet aggregation to epinephrine was divided into quartiles. The platelet response to the other agonists was analysed based on the response to epinephrine. Results: Platelet reactivity increased significantly across the quartiles in response to epinephrine in healthy volunteers and patients (Pu2003<u20030.0001). A significant increase in response across quartiles was seen with all agonists in healthy volunteers (Pu2003<u20030.001). In contrast, a significant increase in response across quartiles was only seen with ADP in patients (Pu2003<u20030.0001). Hypertension, smoking and diabetes were significantly associated with increasing platelet reactivity to epinephrine (Pu2003<u20030.05). Conclusion: This study shows that platelet response differs between healthy volunteers and patients on dual antiplatelet therapy. In patients with cardiovascular disease, dual antiplatelet therapy unmasks a distinct type of platelet reactivity in response to epinephrine and ADP but not other agonists.

Six-month and one-year clinical outcomes after placement of a dedicated coronary bifurcation stent: A patient-level pooled analysis of eight registry studies

AIMSnSmaller studies have previously shown promising results after Tryton Side Branch Stent™ (Tryton Medical, Durham, NC, USA) placement. However, these previous studies were limited by their small sample size and relatively short follow-up. We performed a patient-level pooled analysis to evaluate six-month and one year clinical outcomes of more than 900 patients who were enrolled in eight registries with the Tryton stent.nnnMETHODS AND RESULTSnData from eight Tryton registries, including 905 patients with 929 bifurcation lesions, were pooled on a patient level to form one dataset. The primary outcome was six-month target vessel failure (TVF), defined as the composite of cardiac death, any myocardial infarction, and clinically indicated target vessel revascularisation. Procedural success was defined as successful stent placement and no in-hospital major adverse cardiac events. Multivariable analysis was performed to determine independent predictors for one-year TVF. Follow-up data were available in 97%. Procedural success was 95% and TVF rate was 6.5% at six months and 8.5% at one year. Stent thrombosis occurred in 0.5% of patients. Left main coronary artery bifurcation lesion (HR 6.46) and main branch reference vessel diameter <3.0 mm (HR 2.62) were independent predictors for TVF.nnnCONCLUSIONSnIn the real world setting of registries including more than 900 patients, the use of the Tryton stent is associated with procedural and mid-term clinical results that compare very favourably with historical studies. The primary endpoint of TVF was primarily determined by reference vessel diameter of the main branch and left main bifurcation lesion location.

Platelet reactivity in type 2 diabetes mellitus: a comparative analysis with survivors of myocardial infarction and the role of glycaemic control.

Aims: Patients with type 2 diabetes mellitus exhibit considerable platelet dysfunction, though this is poorly characterized in patients with diabetes taking aspirin for the primary prevention of cardiovascular events. We sought to compare platelet function in this patient population with that of a high-risk group of non-diabetic subjects with a history of previous myocardial infarction (MI), and to assess whether glycaemic control impacts on platelet function. Methods: Platelet aggregation was measured in response to incremental concentrations of five platelet agonists using light transmission aggregometry. All patients were taking aspirin, and aspirin insensitivity was defined as ≥20% arachidonic acid (AA) mediated aggregation. Patients with diabetes were divided according to glycaemic control (HbA1c): optimal ≤6.5, good 6.6–7.4 and suboptimal ≥7.5%. Results: In total, 85 patients with type 2 diabetes and 35 non-diabetic patients with previous MI were recruited. Compared to MI patients, diabetes patients had increased aggregation in response to multiple concentrations of epinephrine, collagen, adenosine diphosphate and AA. Aspirin insensitivity was more common in type 2 diabetes (15% vs. 0%, pu2009=u20090.037). Platelet aggregation was increased in response to several agonists patients with suboptimal glycaemic control compared to patients with optimal control. Aspirin insensitivity was also more common in patients with suboptimal glycaemic control compared to those with good or optimal control (26.0% vs. 8.3% vs. 4%, pu2009=u20090.04). Conclusion: Patients with type 2 diabetes mellitus, without proven vascular disease, exhibit platelet dysfunction and have increased platelet aggregation and aspirin insensitivity compared to non-diabetic patients with previous MI. Platelet dysfunction in diabetes is more severe in patients with suboptimal glycaemic control.

Reducing intra-individual variation in platelet aggregation: implications for platelet function testing

Haemost 2007; 5: 2197–203. 5 AngiolilloDJ, BernardoE,RamirezC, CostaMA, SabateM, JimenezQuevedo P, Hernandez R,Moreno R, Escaned J, Alfonso F, Banuelos C, Bass TA, Macaya C, Fernandez-Ortiz A. Insulin therapy is associated with platelet dysfunction in patients with type 2 diabetes mellitus on dual oral antiplatelet treatment. J Am Coll Cardiol 2006; 48: 298– 304. 6 Angiolillo DJ, Fernandez-Ortiz A, Bernardo E, Ramirez C, Sabate M, Jimenez-Quevedo P, Hernandez R, Moreno R, Escaned J, Alfonso F, Banuelos C, Costa MA, Bass TA, Macaya C. Clopidogrel withdrawal is associated with proinflammatory and prothrombotic effects in patients with diabetes and coronary artery disease. Diabetes 2006; 55: 780–4. 7 Lepantalo A, Virtanen KS, Heikkila J, Wartiovaara U, Lassila R. Limited early antiplatelet effect of 300 mg clopidogrel in patients with aspirin therapy undergoing percutaneous coronary interventions. Eur Heart J 2004; 25: 476–83. 8 Cuisset T, Frere C, Quilici J, Barbou F, Morange PE, Hovasse T, Bonnet JL, Alessi MC. High post-treatment platelet reactivity identified low-responders to dual antiplatelet therapy at increased risk of recurrent cardiovascular events after stenting for acute coronary syndrome. J Thromb Haemost 2006; 4: 542–9. 9 Ang L. Elevated plasma fibrinogen and diabetes mellitus are associated with lower inhibition of platelet reactivity with clopidogrel. J Am Coll Cardiol 2008; 52: 1052–9.

Individual platelet adhesion assay: measuring platelet function and antiplatelet therapies in whole blood via digital quantification of cell adhesion.

Widespread monitoring of platelet function and the effect of antiplatelet drugs will improve outcomes in cardiovascular patients, but platelet function testing is not routine in clinical practice. We report a rapid, accurate methodology to quantify platelet-protein interactions: a microarray of contact-printed 6-μm fibrinogen dots on a transparent substrate binds platelets from whole blood, one platelet per dot. The fractional occupancy of an array of fibrinogen dots after a predefined incubation time quantitatively assays platelet adhesion to the protein matrix. We demonstrate this technique by measurement of platelet adhesion to fibrinogen as a means to quantify the effect of the P2Y12 and αIIbβ3 receptor inhibitors cangrelor and abciximab, respectively, both in vitro--by incubating the drug with a freshly drawn blood sample--and in blood from patients treated with antiplatelet agents. The effects of single- and dual-antiplatelet therapy are also assessed. Results from this platelet-binding assay are well correlated with standard techniques including flow cytometry and light transmission aggregometry. This assay technology, readily integrated with microfluidic platforms, is generally applicable to the assay of cell-protein interactions and promises more effective, rapid assay of drug effects in cardiovascular disease patients.

Clinical outcomes after final kissing balloon inflation compared with no final kissing balloon inflation in bifurcation lesions treated with a dedicated coronary bifurcation stent

Objective We evaluated differences in clinical outcomes between patients who underwent final kissing balloon inflation (FKBI) and patients who did not undergo FKBI in bifurcation treatment using the Tryton Side Branch Stent (Tryton Medical, Durham, North Carolina, USA). Methods Clinical outcomes were defined as target vessel failure (composite of cardiac death, any myocardial infarction and clinically indicated target vessel revascularisation), cardiac death, myocardial infarction (MI), clinically indicated target vessel revascularisation and stent thrombosis. Cumulative event rates were estimated using the Kaplan-Meier method. A multivariable logistic regression analysis was performed to evaluate which factors were potentially associated with FKBI performance. Results Follow-up data was available in 717 (96%) patients with a median follow-up of 190u2005days. Cardiac death at 1 year occurred more often in the no-FKBI group (1.7% vs 4.6%, respectively, p=0.017), although this difference was no longer observed after excluding patients presenting with ST segment elevation MI (1.6% vs 3.3%, p=0.133). No significant differences were observed concerning the other clinical outcomes. One-year target vessel failure rates were 10.1% in the no-FKBI group and 9.2% in the FKBI group (p=0.257). Multivariable logistic regression analysis identified renal dysfunction, ST segment elevation MI as percutaneous coronary intervention indication, narrow (<30°) bifurcation angle and certain stent platforms as being independently associated with unsuccessful FKBI. Conclusions A lower cardiac death rate was observed in patients in whom FKBI was performed compared with a selection of patients in whom FKBI could not be performed, probably explained by an unbalance in the baseline risk profile of the patients. No differences were observed regarding the other clinical outcomes.

Platelet Function Testing: Methods of Assessment and Clinical Utility

Platelets play a central role in the regulation of both thrombosis and haemostasis yet tests of platelet function have, until recently, been exclusively used in the diagnosis and management of bleeding disorders. Recent advances have demonstrated the clinical utility of platelet function testing in patients with cardiovascular disease. The ex vivo measurement of response to antiplatelet therapies (aspirin and clopidogrel), by an ever-increasing array of platelet function tests, is with some assays, predictive of adverse clinical events and thus, represents an emerging area of interest for both the clinician and basic scientist. This review article will describe the advantages and disadvantages of the currently available methods of measuring platelet function and discuss both the limitations and emerging data supporting the role of platelet function studies in clinical practice.