Introduction
Current European and North-American guidelines provide a Class I recommendation for the administration of dual antiplatelet therapy to patients presenting with acute coronary syndrome (ACS) who are undergoing percutaneous coronary intervention (PCI), consisting of aspirin to inhibit platelet thromboxane production and one of the newer P2Y12 receptor antagonists, such as prasugrel, to prevent secondary platelet activation [
1,
2]. This recommendation was introduced following large classic randomised trials [
3,
4].
As with every novel pharmacological principle, documentation of real-life contemporary results is of utmost importance, especially when considering that baseline and procedural characteristics in clinical trial participants differ considerably from those in non-participants along with a better survival observed in trial participants [
5]. In this sense longitudinal clinical registries that provide information on the effectiveness and safety in real-world patient populations are of utmost importance. Accordingly, our aim was to study the introduction of prasugrel into contemporary practice to understand the appropriateness of its use. Hence, we aimed to observe treatment patterns and 1‑year outcomes associated with routine prasugrel treatment using a tailored strategy in PCI-treated ACS patients in the large-scale prospective Rijnmond Collective Cardiology Research (CCR) study.
Discussion
In this large-scale registry, 81% of all consecutive ACS patients treated with PCI who were eligible for a newer and more potent guideline-recommended P2Y12 receptor antagonist were discharged on prasugrel. These patients exhibited low rates of ischaemic events, including overall mortality post discharge, and low rates of major bleeding events in routine contemporary practice. These data provide important evidence with regard to the efficacy and safety of real-world use of prasugrel as part of an antiplatelet strategy with a tailored approach.
Our findings are consistent with the TRITON-TIMI 38 trial in terms of efficacy of prasugrel, with an even better safety profile. In TRITON-TIMI 38, prasugrel reduced the incidence of the primary endpoint of cardiovascular death, MI, and stroke compared with clopidogrel (9.9% vs. 12.1%;
P < 0.001) in ACS patients undergoing PCI, but it also increased the risk for non-CABG TIMI major bleeding, particularly among the elderly (≥75 years), as well as in those with low body weight (<60 kg), prior stroke or TIA [
3]. We observed much lower rates of efficacy endpoints along with low rates of bleeding. These results may be explained, at least in part, by the low-risk profile of the current study population and demonstrate the efficacy of our tailored approach in routine clinical practice where potentially 66% of all ACS-PCI patients were on full-dose high-effective dual antiplatelet therapy. In fact, our results are much more in line with recent TRITON-TIMI 38 subanalyses [
8] in which the benefit of prasugrel was maximised and the risk of adverse outcomes limited by excluding high-risk patients. Importantly, in-hospital deaths after the index procedure were not part of the study cohort (
N = 121) and non-fatal major bleeding events among these patients were limited (
n = 7, of which 3 on prasugrel), whereas in-hospital bleeding events in the study cohort were still included for the analysis. In this respect, the currently observed low mortality rate is partly explained by our focus on hospital survivors only, whereas hospital mortality was mainly driven by patients with out-of-hospital cardiac arrest or patients who presented with cardiogenic shock.
When we focus on bleeding events, we see that prasugrel pretreatment significantly increased bleeding complications in ACCOAST-PCI [
9], although the incidence of major bleeding was low at 30 days (1.7 and 0.66% in the pretreatment and no-pretreatment groups, respectively). The incidence of major bleeding at 30 days in the CCR registry was 0.8%. This is perfectly in line with the results from the ACCOAST-PCI study, and remarkably close to the bleeding events in the no-pretreatment arm. In this regard we should mention the higher number of radial artery access (56%) in the CCR study versus 56% femoral approaches in the ACCOAST-PCI study [
9]. A recent subanalysis of the ACCOAST-PCI study demonstrated that pretreatment, age, gender and procedural variables (femoral access) were independent predictors of TIMI major or minor bleeding in patients with NSTEMI, a finding in line with the current results [
10].
Our results extend previous observations in registries of PCI-treated ACS patients [
11,
12]. For instance, Damman et al. demonstrated low rates of in-hospital bleeding and 30-day mortality for prasugrel in an analysis of the SCAAR data [
11]. Our data are also in keeping with the recent large-scale TRANSLATE-ACS registry demonstrating lower (unadjusted) MACE in patients receiving prasugrel (
n = 3,123) versus clopidogrel (
n = 8,846) [
13]. In contrast, the current observational study was initiated after an update of the treatment guidelines to include prasugrel as the first-line treatment option for antiplatelet therapy. Based on the strategy in our study, 65% of patients were discharged on prasugrel versus 26% in the TRANSLATE-ACS registry. With the current strategy we were also able to limit inappropriate or non-recommended use of prasugrel in contrast to another national registry [
14].
In the current registry, 33% of patients were discharged on clopidogrel. To a large extent, this observation can be explained by the tailored approach for the use of prasugrel in our network with an individual risk-benefit evaluation in patients with ACS who are undergoing PCI. This percentage could have been lower if the 5 mg dosage for patients with an increased bleeding risk would have been reimbursed by health insurers in the Netherlands. Nonetheless, the tailored protocol enabled physicians to adequately triage patients to prasugrel according to their baseline and/or bleeding risk, thereby optimising safety and outcomes, as demonstrated by the present low ischaemic and low bleeding event rates. Currently, prasugrel and ticagrelor are the recommended first-line agents in patients with ACS. We cannot reliably establish which drug is superior over the other on the basis of the current data [
15]. For example, both agents are similarly effective during the first year after MI [
16] and based on a recent meta-analysis of observational and randomised studies totalling 21,360 patients, prasugrel appeared to be equivalent or superior to ticagrelor in patients with ACS who are undergoing PCI at 1‑month follow-up [
17].
Our findings should be considered in the context of the following potential limitations. Inherent for all single-arm registry data, final efficacy and safety versus other strategies cannot be claimed. A follow-up rate of 97.7% at one month and 91.3% at one year represents substantial completeness of our data. Yet is unlikely that we missed any deaths (or potential major bleeding events leading to death) through confirmation of municipal civil registries. Even though we may have missed additional endpoints, we believe this may not considerably impact the overall conclusions of our findings.
Nonetheless, our data provide an objective snapshot of the use of prasugrel in daily practice where patients are selected on known increased bleeding characteristics, affording valuable insights into treatment effectiveness and generalisability [
18]. The adherence rate of 81% at discharge, the potential prasugrel cohort on target therapy as described in the results section, was based only on prescription data and follow-up, as well as on patient interviews at the outpatient clinics of the enrolling sites. Unfortunately, the design of the study did not allow us to collect information regarding reasons for discontinuation, interruption or disruption of prasugrel [
19]. Furthermore, we did not collect information regarding treatment decisions such as the specific reasoning for initially selecting thienopyridine or switching to thienopyridine in-hospital. Nor did we collect any information regarding specific timings such as the exact time of thienopyridine loading or time from loading dose to starting angiography/PCI.