New Antiplatelet Agents and the Role of Platelet Function Testing in Acute Coronary Syndromes

Background

Dual antiplatelet therapy is a guideline mandated for patients with acute coronary syndromes (ACS). Despite its use, thrombotic events continue to occur both early and late. Platelet function testing has been used to define the in vitro effects of new antiplatelet agents, and it has been suggested that it be used to choose therapy. The role of platelet function testing, particularly with newer antiplatelet agents, remains unclear.

Objective

We review the rationale for platelet function testing and its application in monitoring patients on antiplatelet therapy. We also review recent clinical trials of newer antiplatelet agents. On the basis of this review, we reach conclusions on the current role of antiplatelet function testing in monitoring modern antiplatelet therapy and the role of the new antiplatelet agents in the treatment of ACS.

Methods

We reviewed recent publications on platelet function testing and clinical trials of newer antiplatelet therapies compared with clopidogrel.

Results

Platelet function testing is complex, but there is now a bedside test, VerifyNow. High platelet reactivity has been associated with worse cardiovascular outcomes in patients undergoing percutaneous coronary intervention. Recent clinical trials have not found any advantage in outcomes in patients who have their therapy adjusted by monitoring their platelet function. Newer agents, prasugrel, ticagrelor, and cangrelor, produce more rapid, complete, less variable effects on platelet function than clopidogrel. Prasugrel was found to improve outcomes compared with clopidogrel in patients with ACS undergoing percutaneous intervention. Ticagrelor is beneficial in all patients with ACS and reduces cardiovascular mortality compared with clopidogrel. Cangrelor improves outcomes in patients undergoing stenting. Recent studies to assess the role of platelet function monitoring of the effects of clopidogrel and modifying treatments have not been successful.

Conclusion

Recent clinical trials have indicated that newer antiplatelet agents have advantages over clopidogrel in the treatment of ACS. Platelet function testing gives us a guide to the timing, efficacy, and variability of therapy and can correlate with poor patient outcomes; however, the use of antiplatelet function testing to tailor therapy does not seem appropriate.     

Triage to electrocardiogram sign-off time in patients with acute coronary syndrome at a metropolitan Sydney hospital

Objective

To compare the time from triage to ECG sign-off in patients with acute coronary syndrome, before and after the introduction of an electronic medical record-integrated ECG workflow system (Epiphany). Additionally, to assess for any correlation between patient characteristics and ECG sign-off times.

Methods

A retrospective, single-centre cohort study was performed at Prince of Wales Hospital, Sydney. Patients were included if they were over 18 years, presented to Prince of Wales Hospital ED during 2021, had an ED diagnosis code of ‘ACS’, ‘UA’, ‘NSTEMI’ or ‘STEMI’ and were subsequently admitted under the cardiology team. ECG sign-off times and demographic data were compared between patients presenting prior to 29 June (pre-Epiphany group) and those presenting after (post-Epiphany group). Those without ECGs signed-off were excluded.

Results

There were 200 patients (100 each group) included in the statistical analysis. There was a significant decrease in the median triage to ECG sign-off time, from 35 min (IQR 18–69) pre-Epiphany, to 21 min (IQR 13–37) post-Epiphany. There were only 10 (5%) patients in the pre-Epiphany group and 16 (8%) in the post-Epiphany group, who had ECG sign-off times less than the 10-min. There was no correlation between gender, triage category, age or time of shift with triage to ECG sign-off time.

Conclusions

The introduction of the Epiphany system has significantly reduced the triage to ECG sign-off time in the ED. Despite this, there remains a large proportion of patients with acute coronary syndrome who do not have an ECG signed-off within the guideline-recommended 10 min.