Michelle L. O'Donoghue

Pharmacodynamic effect and clinical efficacy of clopidogrel and prasugrel with or without a proton-pump inhibitor: an analysis of two randomised trials

BACKGROUND Proton-pump inhibitors (PPIs) are often prescribed in combination with thienopyridines. Conflicting data exist as to whether PPIs diminish the efficacy of clopidogrel. We assessed the association between PPI use, measures of platelet function, and clinical outcomes for patients treated with clopidogrel or prasugrel. METHODS In the PRINCIPLE-TIMI 44 trial, the primary outcome was inhibition of platelet aggregation at 6 h assessed by light-transmission aggregometry. In the TRITON-TIMI 38 trial, the primary endpoint was the composite of cardiovascular death, myocardial infarction, or stroke. In both studies, PPI use was at physicians discretion. We used a multivariable Cox model with propensity score to assess the association of PPI use with clinical outcomes. FINDINGS In the PRINCIPLE-TIMI 44 trial, 201 patients undergoing elective percutaneous coronary intervention were randomly assigned to prasugrel (n=102) or high-dose clopidogrel (n=99). Mean inhibition of platelet aggregation was significantly lower for patients on a PPI than for those not on a PPI at 6 h after a 600 mg clopidogrel loading dose (23.2+/-19.5% vs 35.2+/-20.9%, p=0.02), whereas a more modest difference was seen with and without a PPI after a 60 mg loading dose of prasugrel (69.6+/-13.5% vs 76.7+/-12.4%, p=0.054). In the TRITON-TIMI 38 trial, 13,608 patients with an acute coronary syndrome were randomly assigned to prasugrel (n=6813) or clopidogrel (n=6795). In this study, 33% (n=4529) of patients were on a PPI at randomisation. No association existed between PPI use and risk of the primary endpoint for patients treated with clopidogrel (adjusted hazard ratio [HR] 0.94, 95% CI 0.80-1.11) or prasugrel (1.00, 0.84-1.20). INTERPRETATION The current findings do not support the need to avoid concomitant use of PPIs, when clinically indicated, in patients receiving clopidogrel or prasugrel. FUNDING Daiichi Sankyo Company Limited and Eli Lilly and Company sponsored the trials. This analysis had no funding.

Safety and tolerability of atopaxar in the treatment of patients with acute coronary syndromes: the lessons from antagonizing the cellular effects of Thrombin–Acute Coronary Syndromes Trial.

Background— Atopaxar (E5555) is a reversible protease-activated receptor-1 thrombin receptor antagonist that interferes with platelet signaling. The primary objective of the Lessons From Antagonizing the Cellular Effects of Thrombin–Acute Coronary Syndromes (LANCELOT—ACS) trial was to evaluate the safety and tolerability of atopaxar in patients with ACS. Methods and Results— Six hundred and three subjects were randomized within 72 hours of non–ST-elevation ACS to 1 of 3 doses of atopaxar (400-mg loading dose followed by 50, 100, or 200 mg daily) or matching placebo. The incidence of Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) major or minor bleeding did not differ significantly between the combined atopaxar and placebo groups (3.08% versus 2.17%, respectively; P=0.63), and there was no dose-related trend (P=0.80). The incidence of CURE major bleeding was numerically higher in the atopaxar group compared with the placebo group (1.8% versus 0%; P=0.12). The incidence of cardiovascular death, myocardial infarction, stroke, or recurrent ischemia was similar between the atopaxar and placebo arms (8.03% versus 7.75%; P=0.93). The incidence of CV death, MI, or stroke was 5.63% in the placebo group and 3.25% in the combined atopaxar group (P=0.20). Dose-dependent trends for efficacy were not seen. Atopaxar significantly reduced ischemia on continuous ECG monitoring (Holter) at 48 hours compared with placebo (relative risk, 0.67; P=0.02). Transient dose-dependent transaminase elevation and relative QTc prolongation were observed with the highest doses of atopaxar. Conclusion— In patients after ACS, atopaxar significantly reduced early ischemia on Holter monitoring without a significant increase in major or minor bleeding. Larger trials are required to fully establish the efficacy and safety of atopaxar. Clinical Trial Registration— URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00548587.Background— Atopaxar (E5555) is a reversible protease-activated receptor-1 thrombin receptor antagonist that interferes with platelet signaling. The primary objective of the Lessons From Antagonizing the Cellular Effects of Thrombin–Acute Coronary Syndromes (LANCELOT—ACS) trial was to evaluate the safety and tolerability of atopaxar in patients with ACS. Methods and Results— Six hundred and three subjects were randomized within 72 hours of non–ST-elevation ACS to 1 of 3 doses of atopaxar (400-mg loading dose followed by 50, 100, or 200 mg daily) or matching placebo. The incidence of Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) major or minor bleeding did not differ significantly between the combined atopaxar and placebo groups (3.08% versus 2.17%, respectively; P =0.63), and there was no dose-related trend ( P =0.80). The incidence of CURE major bleeding was numerically higher in the atopaxar group compared with the placebo group (1.8% versus 0%; P =0.12). The incidence of cardiovascular death, myocardial infarction, stroke, or recurrent ischemia was similar between the atopaxar and placebo arms (8.03% versus 7.75%; P =0.93). The incidence of CV death, MI, or stroke was 5.63% in the placebo group and 3.25% in the combined atopaxar group ( P =0.20). Dose-dependent trends for efficacy were not seen. Atopaxar significantly reduced ischemia on continuous ECG monitoring (Holter) at 48 hours compared with placebo (relative risk, 0.67; P =0.02). Transient dose-dependent transaminase elevation and relative QTc prolongation were observed with the highest doses of atopaxar. Conclusion— In patients after ACS, atopaxar significantly reduced early ischemia on Holter monitoring without a significant increase in major or minor bleeding. Larger trials are required to fully establish the efficacy and safety of atopaxar. Clinical Trial Registration— URL: . Unique identifier: [NCT00548587][1]. # Clinical Perspective {#article-title-19} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00548587&atom=%2Fcirculationaha%2F123%2F17%2F1843.atom

The Efficacy and Safety of Prasugrel With and Without a Glycoprotein IIb/IIIa Inhibitor in Patients With Acute Coronary Syndromes Undergoing Percutaneous Intervention: A TRITON-TIMI 38 (Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel-Thrombolysis In Myocardial Infarction 38) Analysis

OBJECTIVES We evaluated the efficacy and safety of prasugrel and clopidogrel in the setting of a glycoprotein (GP) IIb/IIIa inhibitor. BACKGROUND Prasugrel reduced cardiovascular events as compared with clopidogrel in TRITON-TIMI 38 (Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition with Prasugrel-Thrombolysis in Myocardial Infarction 38) but with increased bleeding. METHODS Researchers in the TRITON-TIMI 38 randomized 13,608 subjects with acute coronary syndrome undergoing percutaneous coronary intervention to prasugrel versus clopidogrel. The use of a GP IIb/IIIa inhibitor was at the physicians discretion. For the current analysis, end points were examined at 30 days and were stratified by use of a GP IIb/IIIa inhibitor. RESULTS A total of 7,414 subjects (54.5%) received a GP IIb/IIIa inhibitor during their index hospitalization. There was a consistent benefit of prasugrel over clopidogrel for reducing cardiovascular death, myocardial infarction, or stroke in patients who did (hazard ratio: 0.76; 95% confidence interval: 0.64 to 0.90) or did not receive a GP IIb/IIIa inhibitor (hazard ratio: 0.78; 95% confidence interval: 0.63 to 0.97, p(interaction) = 0.83). Prasugrel significantly reduced myocardial infarction, urgent revascularization, and stent thrombosis irrespective of GP IIb/IIIa inhibitor use. Although subjects treated with a GP IIb/IIIa inhibitor had greater rates of bleeding, the risk of Thrombolysis in Myocardial Infarction major or minor bleeding with prasugrel versus clopidogrel was not significantly different in patients who were or were not treated with GP IIb/IIIa inhibitor (p(interaction) = 0.19). CONCLUSIONS Prasugrel significantly reduces the risk of cardiovascular events in patients with acute coronary syndromes after percutaneous coronary intervention regardless of whether or not a GP IIb/IIIa inhibitor is used. The use of a GP IIb/IIIa inhibitor does not accentuate the relative risk of bleeding with prasugrel as compared with clopidogrel.

Randomized Trial of Atopaxar in the Treatment of Patients With Coronary Artery Disease The Lessons From Antagonizing the Cellular Effect of Thrombin–Coronary Artery Disease Trial

Background— Thrombin is a key mediator of platelet activation. Atopaxar is a reversible protease-activated receptor-1 antagonist that interferes with thrombin-mediated platelet effects. The phase II Lessons From Antagonizing the Cellular Effect of Thrombin–Coronary Artery Disease (LANCELOT–CAD) trial examined the safety and tolerability of prolonged therapy with atopaxar in subjects with CAD. Methods and Results— Subjects with a qualifying history were randomized in a double-blind fashion to 3 dosing regimens of atopaxar (50, 100, or 200 mg daily) or matching placebo for 24 weeks and followed up for an additional 4 weeks. The key safety end points were bleeding according to the Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) and Thrombolysis in Myocardial Infarction (TIMI) classifications. Secondary objectives included platelet aggregation and major adverse cardiac events. Seven hundred and twenty subjects were randomized. Overall bleeding rates tended to be higher with atopaxar compared with placebo by CURE criteria (placebo, 0.6%; atopaxar, 3.9%; relative risk, 6.82, P=0.03; 50 mg, 3.9%; 100 mg, 1.7%; 200 mg, 5.9%; P for trend=0.01) and TIMI criteria (placebo, 6.8%; atopaxar, 10.3%; relative risk, 1.52, P=0.17; 50 mg, 9.9%; 100 mg, 8.1%; 200 mg, 12.9%; P for trend=0.07). There was no difference in major bleeding. Major adverse cardiac events were numerically lower in the atopaxar subjects. All atopaxar regimens achieved high levels of platelet inhibition. A transient elevation in liver transaminases and dose-dependent QTc prolongation without apparent complications were observed in higher-dose atopaxar treatment groups. Conclusions— In this dose-ranging study of patients with CAD, treatment with atopaxar resulted in platelet inhibition, more minor bleeding, and numerically but not statistically fewer ischemic events. Larger-scale trials are needed to determine whether these patterns translate into clinically meaningful effects. Clinical Trial Registration— URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00312052.Background— Thrombin is a key mediator of platelet activation. Atopaxar is a reversible protease-activated receptor-1 antagonist that interferes with thrombin-mediated platelet effects. The phase II Lessons From Antagonizing the Cellular Effect of Thrombin–Coronary Artery Disease (LANCELOT–CAD) trial examined the safety and tolerability of prolonged therapy with atopaxar in subjects with CAD. Methods and Results— Subjects with a qualifying history were randomized in a double-blind fashion to 3 dosing regimens of atopaxar (50, 100, or 200 mg daily) or matching placebo for 24 weeks and followed up for an additional 4 weeks. The key safety end points were bleeding according to the Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) and Thrombolysis in Myocardial Infarction (TIMI) classifications. Secondary objectives included platelet aggregation and major adverse cardiac events. Seven hundred and twenty subjects were randomized. Overall bleeding rates tended to be higher with atopaxar compared with placebo by CURE criteria (placebo, 0.6%; atopaxar, 3.9%; relative risk, 6.82, P =0.03; 50 mg, 3.9%; 100 mg, 1.7%; 200 mg, 5.9%; P for trend=0.01) and TIMI criteria (placebo, 6.8%; atopaxar, 10.3%; relative risk, 1.52, P =0.17; 50 mg, 9.9%; 100 mg, 8.1%; 200 mg, 12.9%; P for trend=0.07). There was no difference in major bleeding. Major adverse cardiac events were numerically lower in the atopaxar subjects. All atopaxar regimens achieved high levels of platelet inhibition. A transient elevation in liver transaminases and dose-dependent QTc prolongation without apparent complications were observed in higher-dose atopaxar treatment groups. Conclusions— In this dose-ranging study of patients with CAD, treatment with atopaxar resulted in platelet inhibition, more minor bleeding, and numerically but not statistically fewer ischemic events. Larger-scale trials are needed to determine whether these patterns translate into clinically meaningful effects. Clinical Trial Registration— URL: . Unique identifier: [NCT00312052][1]. # Clinical Perspective {#article-title-20} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00312052&atom=%2Fcirculationaha%2F123%2F17%2F1854.atom

Study design and rationale for the Stabilization of pLaques usIng Darapladib—Thrombolysis in Myocardial Infarction (SOLID-TIMI 52) trial in patients after an acute coronary syndrome

BACKGROUND Higher levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) are associated with a higher risk of cardiovascular events and may play a causal role in atherogenesis. Darapladib inhibits Lp-PLA(2) activity in plasma and in arterial plaques and may confer clinical benefit in preventing cardiovascular events. STUDY DESIGN The SOLID-TIMI 52 trial is a randomized, double-blind, placebo-controlled, multicenter, event-driven trial. Approximately 13,000 subjects are being randomized to darapladib (160 mg enteric-coated tablet daily) or matching placebo within 30 days of hospitalization with an acute coronary syndrome. The primary end point is the composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. Secondary end points include major and total coronary events, individual components of the primary end point, and all-cause mortality. The study will continue until approximately 1,500 primary end point events have occurred to achieve 90% power to detect a 15.5% reduction in the primary end point. The median treatment duration is anticipated to be approximately 3 years, with a total study duration of approximately 4.1 years. CONCLUSIONS The SOLID-TIMI 52 trial will determine the clinical benefit of direct inhibition of Lp-PLA(2) activity with darapladib in patients after an acute coronary syndrome.

Natriuretic peptides in heart failure: should therapy be guided by BNP levels?

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. Testing for natriuretic peptide markers, such as B-type natriuretic peptide (BNP) or N-terminal proBNP (NT-proBNP), has emerged as an important tool for the diagnosis and risk stratification of patients with HF. However, questions remain regarding the potential role for natriuretic peptides to guide therapy in patients with HF. In this Review, we address the underlying assumptions and the existing evidence supporting a natriuretic-peptide-guided approach to the outpatient management of HF.

An Invasive or Conservative Strategy in Patients With Diabetes Mellitus and Non-ST-Segment Elevation Acute Coronary Syndromes A Collaborative Meta-Analysis of Randomized Trials

OBJECTIVES The purpose of this study was to conduct a meta-analysis to examine an invasive or conservative strategy in diabetic versus nondiabetic patients. BACKGROUND Diabetic patients are at increased risk of cardiovascular events after an acute coronary syndrome, yet it remains unknown whether they derive enhanced benefit from an invasive strategy. METHODS Randomized trials comparing an invasive versus conservative treatment strategy were identified. The prevalence of cardiovascular events through 12 months was reported for each trial, stratified by diabetes mellitus status and randomized treatment strategy. Relative risk (RR) ratios and absolute risk reductions were combined using random-effects models. RESULTS Data were combined across 9 trials comprising 9,904 subjects of whom 1,789 (18.1%) had diabetes mellitus. The RRs for death, nonfatal myocardial infarction (MI), or rehospitalization with an acute coronary syndrome for an invasive versus conservative strategy were similar between diabetic patients (RR: 0.87; 95% confidence interval [CI]: 0.73 to 1.03) and nondiabetic patients (RR: 0.86; 95% CI: 0.70 to 1.06; p interaction = 0.83). An invasive strategy reduced nonfatal MI in diabetic patients (RR: 0.71; 95% CI: 0.55 to 0.92), but not in nondiabetic patients (RR: 0.98; 95% CI: 0.74 to 1.29; p interaction = 0.09). The absolute risk reduction in MI with an invasive strategy was greater in diabetic than nondiabetic patients (absolute risk reduction: 3.7% vs. 0.1%; p interaction = 0.02). There were no differences in death or stroke between groups (p interactions 0.68 and 0.20, respectively). CONCLUSIONS An early invasive strategy yielded similar RR reductions in overall cardiovascular events in diabetic and nondiabetic patients. However, an invasive strategy appeared to reduce recurrent nonfatal MI to a greater extent in diabetic patients. These data support the updated guidelines that recommend an invasive strategy for patients with diabetes mellitus and non-ST-segment elevation acute coronary syndromes.

Impact of smoking on antiplatelet effect of clopidogrel and prasugrel after loading dose and on maintenance therapy.

BACKGROUND Pharmacodynamic studies reported an amplified on-clopidogrel platelet inhibition in smokers potentially caused by an increased metabolic drug activation via induction of cytochrome P450 1A2. The aims of this analysis were to evaluate the impact of smoking on the antiplatelet effect of clopidogrel and prasugrel and to test the potential interaction of smoking with the treatment effect of these drugs. METHODS A variety of platelet function results was analyzed from 2 large cohorts of patients undergoing coronary intervention after loading with clopidogrel 600 mg (n = 2,533 and n = 1,996), a cohort of patients undergoing dose adaptation from 75 to 150 mg according to response to clopidogrel (n = 117) and a crossover trial comparing clopidogrel 150 mg with prasugrel 10 mg (n = 87). Linear regression analyses were used to test the impact of smoking on platelet function and to identify independent predictors of on-treatment platelet reactivity. The potential interaction of smoking with the clinical effect of clopidogrel versus prasugrel was analyzed in the TRITON-TIMI 38 cohort (n = 13,608). RESULTS No significant association of smoking with platelet reactivity on clopidogrel was seen in unadjusted and adjusted analyses. The variables most consistently associated with on-clopidogrel platelet function were age, sex, diabetes, and body mass index. There was no significant interaction of smoking status at presentation with the clinical efficacy of prasugrel versus clopidogrel (P for interaction = .39). CONCLUSIONS Smoking does not impact on platelet reactivity in patients after loading or on different maintenance doses of clopidogrel. The clinical treatment effect of clopidogrel versus prasugrel is not affected by smoking status at presentation.

Variability of individual platelet reactivity over time in patients treated with clopidogrel: insights from the ELEVATE-TIMI 56 trial.

BACKGROUND The degree of antiplatelet response to clopidogrel has been associated with clinical outcomes. Studies have investigated whether adjustment of antiplatelet therapies based on a single platelet function test is beneficial. OBJECTIVES The aim of the study was to test the stability of platelet reactivity measurements over time among patients treated with standard and double doses of clopidogrel. METHODS The ELEVATE-TIMI 56 (Escalating Clopidogrel by Involving a Genetic Strategy-Thrombolysis In Myocardial Infarction 56) investigators genotyped 333 patients with coronary artery disease and randomized them to various clopidogrel regimens. Patients with at least 2 platelet function results on the same maintenance dose of clopidogrel (75 mg or 150 mg) were analyzed. Platelet aggregation was measured using P2Y12 reaction units (PRU). RESULTS In total, the mean platelet reactivity and the total number of nonresponders (PRU ≥230) with clopidogrel did not change between 2 periods for the 75-mg (22.4% vs. 21.9%; p = 0.86) and 150-mg doses of clopidogrel (11.5% vs. 11.5%; p = 1.00). In contrast, when evaluating each patient individually, 15.7% of patients taking clopidogrel 75 mg and 11.4% of patients taking 150 mg had a change in their responder status when tested at 2 different time points (p < 0.001). Despite being treated with the same dose of clopidogrel, >40% of patients had a change in PRU >40 on serial sampling, which approximates the average PRU difference caused by increasing the clopidogrel dose from 75 mg to 150 mg. CONCLUSIONS Measurements of platelet reactivity vary over time in a significant proportion of patients. Thus, treatment adjustment according to platelet function testing at a single time point might not be sufficient for guiding antiplatelet therapy in clinical or research settings. (Escalating Clopidogrel by Involving a Genetic Strategy-Thrombolysis In Myocardial Infarction 56 [ELEVATE-TIMI 56]; NCT01235351).

Association between baseline neutrophil count, clopidogrel therapy, and clinical and angiographic outcomes in patients with ST-elevation myocardial infarction receiving fibrinolytic therapy

AIMS To investigate the association between neutrophil count, outcomes, and benefit of clopidogrel therapy in ST-elevation myocardial infarction (STEMI). METHODS AND RESULTS Baseline neutrophil count was measured in 2865 patients in CLARITY-TIMI 28, a randomized trial of clopidogrel vs. placebo in STEMI patients undergoing fibrinolysis. Angiography was performed at 2-8 days following enrollment. Analyses were adjusted for demographics, time from symptom onset, Killip class, peak CK-MB, and therapies received. A baseline neutrophil count in the highest quartile was independently associated with the risk of cardiovascular (CV) death [adj (adjusted) OR (odds ratio) 5.8, P < 0.001] and congestive heart failure (adj OR 3.0, P = 0.009) at 30 days. Patients with higher neutrophil counts were less likely to achieve complete ST-segment resolution (adj OR 0.76, P = 0.03) or TIMI myocardial perfusion grade 2/3 (adj OR 0.71, P = 0.017). Clopidogrel had a lesser effect on reducing the odds of a closed infarct-related artery, or death or MI before angiography, in patients with a neutrophil count above the median (adjusted OR 0.83, 0.61-1.13) vs. in those below the median (adjusted OR 0.46, 0.33-0.64) (Pinteraction = 0.008). CONCLUSION In patients with STEMI, higher baseline neutrophil count is associated with worse angiographic findings and increased CV mortality, as well as a diminished benefit of clopidogrel.