Comparative Effectiveness of Oral Antiplatelet Agents in Patients with Acute Coronary Syndrome

Comparative effectiveness and safety of prasugrel versus ticagrelor following percutaneous coronary intervention: An observational study

BACKGROUND

Observational studies comparing ticagrelor and prasugrel in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) have yielded contradictory results, but these studies often did not consider differential censoring (eg, for treatment switching or insurance disenrollment) or confounding by time-dependent factors.

OBJECTIVE

Our objective was to conduct a comparative effectiveness and safety analysis of ticagrelor and prasugrel in patients who underwent PCI after being hospitalized for an ACS.

METHODS

This study used the Optum's de-identified Clinformatics^® Data Mart Database and included patients aged 18 years or older with an index hospital admission between May 2012 and September 2015, a diagnosis of ACS managed with PCI, and treatment with either ticagrelor or prasugrel. The primary composite outcome was defined as the first occurrence of all-cause death, myocardial infarction (MI), or ischemic stroke. The secondary composite outcome included the first occurrence of gastrointestinal (GI) bleed, intracranial hemorrhage (ICH), or other major bleeds requiring hospitalization. Weighted Cox proportional hazard models and robust variance estimation were implemented to adjust for baseline comorbidities, time-varying exposure, time-dependent confounders, and differential censoring.

RESULTS

Included in the analysis were 2559 patients initiated on ticagrelor and 4456 patients initiated on prasugrel following PCI. Patients initiated on ticagrelor were 10% more likely to have eligibility disenrollment (Ticagrelor: 57%, Prasugrel: 47%, p < 0.01) and 7 percentage-points more likely to switch medication (Ticagrelor: 35%, Prasugrel: 28%, p < 0.01). After adjusting for multiple factors, including time-varying exposure and censoring imbalance, ticagrelor was associated with a higher risk of all-cause death, MI, or stroke when compared to prasugrel (Hazard ratio (HR): 1.33; 95% CI: 1.04-1.68). Similarly, ticagrelor was associated with a higher risk in bleeding events when compared with prasugrel (HR: 1.61; 95% CI: 1.19-2.17).

CONCLUSION

When compared with ticagrelor, prasugrel use following PCI for ACS was associated with a lower risk of death, MI, or stroke, as well as a reduced risk of major bleeding.

Loading doses of ticagrelor versus clopidogrel in preventing periprocedural myocardial infarction in Asian patients with acute coronary syndrome

BACKGROUND

Periprocedural myocardial infarction is a common complication following percutaneous coronary intervention. The present study was conducted with an aim to compare the safety and efficacy of loading doses of ticagrelor versus clopidogrel in preventing periprocedural myocardial infarction in Asian patients with acute coronary syndrome undergoing elective percutaneous coronary intervention.

METHODS

A total of 114 patients with acute coronary syndrome undergoing elective percutaneous coronary intervention were assigned to clopidogrel group (n = 57, the loading and maintenance doses were 300 and 75 mg qd for clopidogrel, and 300 and 100 mg qd for aspirin), or ticagrelor group (n = 57, the loading and maintenance doses were 180 and 90 mg bid for ticagrelor, and 300 and 100 mg qd for aspirin). Cardiac biomarkers were measured before, 8 hours, and 24 hours after percutaneous coronary intervention. The percutaneous coronary intervention-related periprocedural myocardial infarction was defined according to the fourth universal definition of myocardial infarction (2018).

RESULTS

The overall incidence of percutaneous coronary intervention-related periprocedural myocardial infarction was 21.1%. The ticagrelor group showed a significantly lower incidence of periprocedural myocardial infarction (12.3% vs 29.8%, p = 0.022) and numerically lower bleeding events (3.5% vs 8.8%, p = 0.242) as compared with clopidogrel group. No patient had major adverse cardiovascular events during the 1-month follow-up. The levels of high-sensitivity C-reactive protein did not differ significantly between the two groups (p > 0.05), indicating that the benefits of ticagrelor were not from its anti-inflammatory effects. Multivariable analysis showed that the use of ticagrelor (odds ratio: 0.50; 95% confidence interval: 0.29-0.87; p = 0.014) and number of stents (odds ratio: 2.75; 95% confidence interval: 1.25-6.06; p = 0.012) were independent predictors of periprocedural myocardial infarction.

CONCLUSION

Pretreatment with a loading dose of ticagrelor seems to be superior in reducing the incidence of percutaneous coronary intervention-related periprocedural myocardial infarction in Asian patients with acute coronary syndrome as compared with clopidogrel.

Adenosine and the Cardiovascular System

Adenosine is an endogenous nucleoside with a short half-life that regulates many physiological functions involving the heart and cardiovascular system. Among the cardioprotective properties of adenosine are its ability to improve cholesterol homeostasis, impact platelet aggregation and inhibit the inflammatory response. Through modulation of forward and reverse cholesterol transport pathways, adenosine can improve cholesterol balance and thereby protect macrophages from lipid overload and foam cell transformation. The function of adenosine is controlled through four G-protein coupled receptors: A₁, A_2A, A_2B and A₃. Of these four, it is the A_2A receptor that is in a large part responsible for the anti-inflammatory effects of adenosine as well as defense against excess cholesterol accumulation. A_2A receptor agonists are the focus of efforts by the pharmaceutical industry to develop new cardiovascular therapies, and pharmacological actions of the atheroprotective and anti-inflammatory drug methotrexate are mediated via release of adenosine and activation of the A_2A receptor. Also relevant are anti-platelet agents that decrease platelet activation and adhesion and reduce thrombotic occlusion of atherosclerotic arteries by antagonizing adenosine diphosphate-mediated effects on the P2Y12 receptor. The purpose of this review is to discuss the effects of adenosine on cell types found in the arterial wall that are involved in atherosclerosis, to describe use of adenosine and its receptor ligands to limit excess cholesterol accumulation and to explore clinically applied anti-platelet effects. Its impact on electrophysiology and use as a clinical treatment for myocardial preservation during infarct will also be covered. Results of cell culture studies, animal experiments and human clinical trials are presented. Finally, we highlight future directions of research in the application of adenosine as an approach to improving outcomes in persons with cardiovascular disease.

Comparison of 6-Month Costs Between Oral Antiplatelet Agents Following Acute Coronary Syndrome

BACKGROUND

In patients with acute coronary syndrome (ACS) treated with percutaneous coronary intervention (PCI), newer antiplatelet agents prasugrel and ticagrelor have lower rates of cardiovascular events when compared with clopidogrel. However, it is unclear whether there are differences in economic outcomes when comparing these agents in ACS-PCI patients.

OBJECTIVE

To assess aggregated costs and medical resource utilization among ACS-PCI patients prescribed prasugrel, ticagrelor, or generic clopidogrel, using a large commercial insurance claims database.

METHODS

Costs attributable to any medical and pharmacy service and resource utilization including number of admissions, length of hospital stay, emergency room visits, and office visits over the 180-day postdischarge period were compared. All-cause and cardiovascular health care costs and resource utilization were separately analyzed for patients enrolled in the data over the continuous follow-up (CFU) period, and for patients continuously taking their initial treatment for 6 months (CTX). Potential confounders collected over a 6-month baseline assessment period were controlled for, using a generalized linear model.

RESULTS

Over the 180-day follow-up, prasugrel and ticagrelor patients underwent fewer admissions (rate ratio [RR] = 0.87, 95% CI = 0.80-0.95) from CFU and RR = 0.81, 95% CI = 0.71-0.89 from CTX) compared with clopidogrel patients. The newer agent cohort incurred more overall health care costs than the generic clopidogrel group, with added costs of $957 (95% CI = $236-$1,725) in the CFU group and $1,122 (95% CI = $455-$1,865) in the CTX group, which were smaller than the increase in all-cause outpatient pharmacy costs associated with the newer agents versus clopidogrel (CFU: $1,175, 95% CI = $1,079-$1,278 and CTX: $1,360, 95% CI = $1,256-$1,487). Overall, there was no statistically significant difference in the economic outcomes associated with prasugrel and ticagrelor. There were, however, significant correlations between all-cause and cardiovascular-related outcomes.

CONCLUSIONS

The higher price of prasugrel and ticagrelor was partially offset by a decrease in hospital admission compared with generic clopidogrel over a 6-month postdischarge period. Aggregated medical costs and resource utilization were not significantly different between prasugrel and ticagrelor patients.

DISCLOSURES

No funding was received for this study. DiDomenico has received an honorarium from Amgen for preparation of a heart failure drug monograph for Pharmacy Practice News and serves as an advisory board member for a heart failure program at Otsuka America Pharmaceuticals and for Novartis Pharmaceuticals. Touchette has received unrestricted grant funding from Cardinal Health, Sunovion Pharmaceuticals, and Takeda and has served as a consultant to and director of the American College of Clinical Pharmacy Practice-Based Research Network on a study funded by Pfizer. Walton has served as a paid consultant for Bristol-Myers Squibb, Baxter, Merck, Genentech, Primus, Takeda, and Abbott. The other authors have nothing to disclose.

Antiplatelet Therapy Changes for Patients With Myocardial Infarction With Recurrent Ischemic Events: Insights Into Contemporary Practice From the TRANSLATE-ACS (Treatment With ADP Receptor Inhibitors: Longitudinal Assessment of Treatment Patterns and Events After Acute Coronary Syndrome) Study

BACKGROUND

Guidelines recommend P2Y12 inhibitor therapy for 1 year after myocardial infarction (MI), yet little guidance is provided on antiplatelet management for patients with recurrent ischemic events during that year. We describe changes in P2Y12 inhibitor type among patients with recurrent ischemic events in the first year after MI.

METHODS AND RESULTS

The TRANSLATE-ACS (Treatment With ADP Receptor Inhibitors: Longitudinal Assessment of Treatment Patterns and Events After Acute Coronary Syndrome) study enrolled 12 365 patients with MI treated with percutaneous coronary intervention. We examined whether P2Y12 inhibitor choice changed among patients with recurrent MI, stent thrombosis, and/or unplanned revascularization during the first year after MI, and modeled factors associated with P2Y12 inhibitor intensification (changing clopidogrel to prasugrel or ticagrelor). In the first year after MI, 1414 patients (11%) had a total of 1740 recurrent ischemic events (771 recurrent MIs, 969 unplanned revascularizations, and 165 stent thromboses). Median time to the first recurrent ischemic event was 154 days (25th-75th percentiles, 55-287 days). Of those with recurrent ischemic events, 101 of 1092 (9.3%) occurring in clopidogrel-treated patients led to P2Y12 inhibitor intensification. Recurrent events involving stent thrombosis or MI were the strongest factors associated with P2Y12 inhibitor intensification, yet only 40% of patients with stent thrombosis and 14% of patients with recurrent MI had P2Y12 inhibitor intensification. Increasing age and longer time from the index MI were associated with lower likelihood for intensification.

CONCLUSIONS

Few patients after MI with a recurrent ischemic event who were taking clopidogrel switched to a more potent P2Y12 inhibitor, even after stent thrombosis events. Specific guidance is needed for patients who have recurrent ischemic events, particularly when closely spaced.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01088503.