Comparative Safety and Effectiveness of Loading Doses of P2Y12 Inhibitors in Patients Undergoing Elective PCI: a Network Meta-analysis

PURPOSE

Effective platelet inhibition prior to elective percutaneous coronary intervention (PCI) reduces the risk of ischemic complications. Newer P2Y12 inhibitors are preferred agents over clopidogrel for patients presenting with the acute coronary syndrome. However, the comparative efficacy and safety of them over clopidogrel in elective PCI is unclear. We performed a network meta-analysis to compare the safety and efficacy of loading strategies of P2Y12 inhibitors in patients undergoing elective PCI.

METHODS

We conducted a systematic review of randomized controlled trials (RCT) up to June 2021 to compare the safety and effectiveness of different loading strategies of P2Y12 inhibitors before elective PCI. The endpoints of interest were overall mortality, rates of myocardial infarction (MI), stroke, revascularization, and major bleeding. Random effects model using the frequentist approach was used to perform a network meta-analysis using R software.

RESULTS

Five trials with a total of 5194 patients were included in our analysis. For ischemic outcomes, including MI, stroke, and revascularization, prasugrel had the most favorable trend. However, clopidogrel had the highest probability of being most effective for major bleeding and all-cause mortality. None of these trends was statistically significant due to lack of power for each outcome.

CONCLUSION

Although prasugrel and ticagrelor are known as more potent antiplatelet agents, their effects in preventing MI and stroke are marginal and do not translate into improved overall mortality and bleeding compared with clopidogrel.

P2Y12 Inhibition in Murine Myocarditis Results in Reduced Platelet Infiltration and Preserved Ejection Fraction

Previous mouse studies have shown the increased presence of platelets in the myocardium during early stages of myocarditis and their selective detection by MRI. Here, we aimed to depict early myocarditis using molecular contrast-enhanced ultrasound of activated platelets, and to evaluate the impact of a P2Y12 receptor platelet inhibition. Experimental autoimmune myocarditis was induced in BALB/c mice by subcutaneous injection of porcine cardiac myosin and complete Freund adjuvant (CFA). Activated platelets were targeted with microbubbles (MB) coupled to a single-chain antibody that binds to the "ligand-induced binding sites" of the GPIIb/IIIa-receptor (=LIBS-MB). Alongside myocarditis induction, a group of mice received a daily dose of 100 g prasugrel for 1 month. Mice injected with myosin and CFA had a significantly deteriorated ejection fraction and histological inflammation on day 28 compared to mice only injected with myosin. Platelets infiltrated the myocardium before reduction in ejection fraction could be detected by echocardiography. No selective binding of the LIBS-MB contrast agent could be detected by either ultrasound or histology. Prasugrel therapy preserved ejection fraction and significantly reduced platelet aggregates in the myocardium compared to mice without prasugrel therapy. Therefore, P2Y12 inhibition could be a promising early therapeutic target in myocarditis, requiring further investigation.

P2Y12 inhibition in acute coronary syndromes treated with percutaneous intervention - Understanding the debate on Prasugrel or Ticagrelor

After more than 10 years of routine clinical use, a debate about the preference of prasugrel over ticagrelor has been unveiled following publication of the ISAR-REACT 5 trial, an investigator-initiated trial directly comparing both substances as part of dual anti-platelet therapy following interventional treatment in patients with acute coronary syndromes (ACS). Both substances had been tested in trials, approved by authorities and subsequently recommended by guidelines according to the strategy applied in the respective approval trial. This resulted in prasugrel tested in TRITON only be given after diagnostic coronary angiography in the absence of ST-segment elevations (NSTE-ACS) and ticagrelor tested in PLATO being administered even before diagnostic coronary angiography in all forms of acute coronary syndromes. Whichever way was safest and most efficient, had never been clarified before. ISAR-REACT 5 showed superior efficacy of prasugrel over ticagrelor in general, and of deferred administration of prasugrel over pre-treatment with ticagrelor in NSTE-ACS patients undergoing percutaneous coronary interventions. Subsequently, in 2020 the European guidelines for NSTE-ACS adopted both positions in recommending the respective preference. Afterwards, a confrontational debate erupted between those favouring the ISAR-REACT 5 results and their implementation in guidelines and others still preferring the generalized interpretation of the overall study results from PLATO. In this review, we reflect the history leading to trial design of TRITON and PLATO and the way this subsequently impacted on clinical practice and guideline recommendations.

Optimal Antithrombotic Treatment of Patients with Atrial Fibrillation Early after an Acute Coronary Syndrome-Triple Therapy, Dual Antithrombotic Therapy with an Anticoagulant… Or, Rather, Temporary Dual Antiplatelet Therapy?

The combination of atrial fibrillation (AF) and acute coronary syndrome (ACS) is a complex situation in which a three-dimensional risk-cardioembolic, coronary, and hemorrhagic-has to be carefully managed. Triple antithrombotic therapy (TAT) is burdened with a high risk of serious bleeding, while dual antithrombotic therapy with an anticoagulant (DAT) likely provides only suboptimal coronary protection early after stent implantation. Moreover, TAT precludes the advantages provided by the use of the latest and more potent P2Y₁₂ inhibitors in ACS patients. Here, we aimed to simulate and compare the expected coronary, cardioembolic, and hemorrhagic outcomes offered by DAT, TAT, or modern dual antiplatelet therapy (DAPT) with aspirin plus one of the latest P2Y₁₂ inhibitors in AF patients early after an ACS. The comparison of numbers needed to treat to prevent major adverse events with the various antithrombotic regimens suggests that AF-ACS patients at high ischemic and hemorrhagic risk and at moderately low embolic risk (CHA₂DS₂VASc score 2-4) might safely withhold anticoagulation after revascularization for one month taking advantage of a modern DAPT, with a favorable risk-to-benefit ratio. In conclusion, this strategy, not sufficiently addressed in recent European and North American guidelines or consensus documents, adds to the spectrum of treatment options in these difficult patients; it might be the best choice in a substantial number of patients; and should be prospectively tested in a randomized controlled trial.

Acute Coronary Syndrome, Antiplatelet Therapy, and Bleeding: A Clinical Perspective

Inhibition of platelet function by means of dual antiplatelet therapy (DAPT) is the cornerstone of treatment of acute coronary syndrome (ACS). While preventing ischemic recurrences, inhibition of platelet function is clearly associated with an increased bleeding risk, a feared complication that may lead to significant morbidity and mortality. Since bleeding risk management is intrinsically associated with therapeutic adjustments undertaken during the whole clinical history of patients with acute coronary syndrome, single decisions taken from the very first day to years of follow-up might be decisive. This review aims at providing a clinically oriented, patient-tailored approach in reducing the risk and manage bleeding complications in ACS patients treated with DAPT. The steps in clinical decision making from the day of ACS to follow-up are analyzed. New treatment strategies to enhance the safety of DAPT are also described.

Antithrombotic Strategy for Patients with Acute Coronary Syndrome: A Perspective from East Asia

Dual antiplatelet therapy (DAPT) after percutaneous coronary intervention has become the standard of care, particularly in patients with acute coronary syndrome (ACS). Current clinical guidelines recommend novel P2Y12 inhibitors (e.g., prasugrel or ticagrelor) in addition to aspirin based on the results of representative randomized controlled trials conducted predominantly in Western countries. These agents were superior to clopidogrel in reducing the composite ischemic events, with a trade-off of the increased bleeding events. However, multiple differences exist between East Asian and Western patients, especially with respect to their physique, thrombogenicity, hemorrhagic diathesis, and on-treatment platelet reactivity. Recent studies from East Asian countries (e.g., Japan or South Korea) have consistently demonstrated that use of novel P2Y12 inhibitors is associated with a higher risk of bleeding events than use of clopidogrel, despite borderline statistical difference in the incidence of composite ischemic events. Additionally, multiple studies have shown that the optimal duration of DAPT may be shorter in East Asian than Western patients. This review summarizes clinical studies of antithrombotic strategies in East Asian patients with ACS. Understanding these differences in antithrombotic strategies including DAPT and their impacts on clinical outcomes will aid in selection of the optimal tailored antithrombotic therapy for patients with ACS.

Safety and Cumulative Incidence of Major Cardiovascular Events with Ticagrelor in Taiwanese Patients with Non-ST-Segment Elevation Myocardial Infarction: A 12-Month, Prospective, Phase IV, Multicenter, Single-Arm Study

Background

Ticagrelor, an oral, direct-acting, and reversible P2Y₁₂ receptor antagonist, inhibits platelet activation and aggregation. This phase IV, single-arm study analyzed the safety and tolerability of ticagrelor in Taiwanese patients with non-ST-segment elevation myocardial infarction (NSTEMI) during 1 year of follow-up.

Methods

Patients aged ≥ 20 years with an index event of NSTEMI received ticagrelor (180 mg loading and 90 mg doses twice daily thereafter) plus low-dose aspirin (100 mg/day) for up to 1 year. Safety was evaluated according to adverse events (AEs), serious AEs (SAEs), and PLATO-defined bleeding events. The cumulative incidence of major cardiovascular (CV) events including CV death, myocardial infarction, and stroke was also evaluated.

Results

The safety population included 108 patients across 13 centers in Taiwan. During treatment, 32 (29.6%) patients had ≥ one PLATO-defined bleeding event. Major bleeding events occurred in seven (6.5%) patients with a Kaplan-Meier (KM) estimated event risk [95% confidence interval (CI)] of 7.1% (3.4%-14.4%), including life-threatening bleeding [four (3.7%) patients] and other major bleeding [three (2.8%) patients]. No PLATO-defined fatal bleeding was observed. SAEs were reported in 23 (21.3%) patients. Six (5.6%) patients experienced major CV events during the 1-year follow-up period, with a KM-estimated event risk (95% CI) of 5.6% (2.6%-12.0%).

Conclusions

Ticagrelor for up to 1 year was associated with a low rate of major bleeding events and a low incidence of major CV events in Taiwanese patients with NSTEMI. The overall safety of ticagrelor was in accordance with the known safety profile of ticagrelor.

Preprocedural P2Y12 inhibition and decrease in platelet count following transcatheter aortic valve replacement

BACKGROUND

Thrombocytopenia after transcatheter aortic valve replacement (TAVR) is associated with adverse clinical outcomes. Whether preprocedural P2Y₁₂ inhibition prevents postprocedural thrombocytopenia is uncertain.

METHODS

This retrospective analysis identified consecutive patients (n = 266) undergoing TAVR between November 2016 and July 2017. Preprocedure clopidogrel load ≥300 mg or maintenance P2Y₁₂ inhibitor therapy defined preprocedural P2Y₁₂ inhibition. Patients who did not consent for the registry (n = 8), with baseline severe thrombocytopenia (<90 × 10³  platelets/μL; n = 14), or without baseline platelet count (n = 4) were excluded. The primary outcome was proportion of patients who developed >20% decrease in platelet count from baseline to day 1 post-TAVR.

RESULTS

Patients with (n = 134) versus without (n = 106) preprocedural P2Y₁₂ inhibition had no differences in platelet count at baseline. Patients with preprocedural P2Y₁₂ inhibition had a significantly lower proportion of the primary outcome (34.3% vs. 57.5%, p = .001) and a lower absolute decrease in platelet count (32.8 × 10³ vs. 45.8 × 10³  platelet/μL, p = .01). Of patients without baseline thrombocytopenia (n = 198), a numerically lower rate of patients with versus without preprocedural P2Y₁₂ inhibition developed thrombocytopenia on day 1 post-TAVR (25.5% vs. 36.4%, p = .1).

CONCLUSION

Patients who received preprocedural P2Y₁₂ inhibition prior to TAVR were less likely to demonstrate a decrease in platelet count after TAVR. Prospective studies to further understand the clinical implication of these findings are warranted.