Is platelet function testing at the acute phase under P2Y12 inhibitors helpful in predicting bleeding in real-life patients with acute coronary syndrome? The AVALANCHE study

BACKGROUND

In patients with acute coronary syndrome (ACS), current international guidelines recommend newer potent and predictable P2Y₁₂ inhibitors as first-line treatment despite a greater bleeding risk compared with clopidogrel.

AIM

To determine if platelet function testing can predict bleeding in real-life patients with ACS treated with newer P2Y₁₂ inhibitors.

METHODS

In this retrospective study, all consecutive adults admitted to the Lariboisière University Hospital for ACS, whatever the P2Y₁₂ inhibitor prescribed, who had platelet function testing (vasodilator-stimulated phosphoprotein phosphorylation [VASP] index and aggregation tests) during the initial hospital stay were included. Follow-up was performed to record bleeding events according to the Bleeding Academic Research Consortium (BARC) classification.

RESULTS

A total of 364 patients were included, treated with ticagrelor (n=123), prasugrel (n=105) or clopidogrel (n=136); 42.3% after an ST-segment elevation myocardial infarction, 27.1% after a non-ST-segment elevation myocardial infarction and 30.6% with unstable angina. Mean age was 64±11 years. Median VASP index was significantly lower with the newer P2Y₁₂ inhibitors (14% under ticagrelor, 14% under prasugrel) than with clopidogrel (42%). Despite these differences in the degree of platelet inhibition, the occurrence of bleeding (BARC 2-5) during follow-up was 7.7% overall, and was similar for all P2Y₁₂ inhibitors (ticagrelor 8.9%; prasugrel 6.6%; clopidogrel 7.4%). For each P2Y₁₂ inhibitor, it was impossible to determine a VASP index threshold under which bleeding was significantly greater during follow-up. Similarly, ADP-induced aggregation was more profoundly inhibited by ticagrelor and prasugrel than by clopidogrel, but this did not allow a threshold to be set for increased haemorrhagic risk.

CONCLUSIONS

Despite the substantial occurrence of bleeding in patients with ACS during follow-up, neither the VASP index nor platelet aggregation test results measured at the acute phase were helpful in predicting bleeding risk. Whether platelet function testing could be helpful later in the course of treatment remains to be evaluated.

Impact of Platelet Reactivity in ACS Patients on Clinical Outcomes with Triple Antithrombotic Therapy

Optimal antithrombotic therapy after percutaneous coronary intervention (PCI) in patients on oral anticoagulants (OAC) remains a clinical conundrum. In fact, combining an OAC with dual antiplatelet therapy (triple antithrombotic therapy, TAT) increases the risk of bleeding. Clopidogrel is the only thienopyridine recommended in TAT patients. Whether its response plays a relevant role in this setting remains uncertain. We aimed to evaluate the level of platelet reactivity inhibition (PRI) achieved by oral TAT in Acute Coronary Syndrome (ACS) patients undergoing PCI and its relationship with outcomes. We performed a multicenter prospective observational study and assessed PRI by vasodilator-stimulated phosphoprotein (VASP) index following a loading dose of clopidogrel. The primary endpoint was the incidence of major adverse cerebral or cardiovascular events (MACCE) at six months based on High on Treatment Platelet Reactivity (HTPR, VASP > 50%). The secondary endpoint was the incidence of bleeding at six months based on Low on Treatment Platelet Reactivity (LTPR, VASP < 16%). 491 patients were followed up for six months: 7.7% experienced MACCE and 17.3% experienced bleeding. There was no significant relationship between HTPR and MACCE, neither between LTPR and bleeding. Vitamin-K antagonist (VKA) treatment was associated with more MACCE and bleeding events, and the majority of events occurred within the first months. VASP index failed to predict outcomes in post-ACS patients with TAT. We confirm that direct acting OAC should be prioritized over VKA in TAT regimen.

Platelet reactivity inhibition following ticagrelor loading dose in patients undergoing percutaneous coronary intervention for acute coronary syndrome

BACKGROUND

Ticagrelor induces more potent platelet reactivity (PR) inhibition with reduced interindividual variability compared to clopidogrel. Although on-clopidogrel PR was shown to correlate with ischemia and bleeding events, no study has investigated the relationship between on-ticagrelor PR and outcome.

OBJECTIVES

We aimed to evaluate the relationship between on-ticagrelor PR, assessed by the vasodilator-stimulated phosphoprotein index (VASP), and thrombotic and bleeding events in patients with acute coronary syndrome (ACS) treated by percutaneous coronary intervention (PCI).

METHODS

We performed a prospective, multicenter observational study on patients treated with PCI for ACS. The VASP index was used to assess PR after ticagrelor loading dose (LD). The primary endpoint was the link between major adverse cardiovascular events (MACE) and PR.

RESULTS

Among the 530 patients with ACS included, 183 (34.5%) were admitted for ST elevation myocardial infarction. We observed high potency and limited interindividual variability after the ticagrelor LD (VASP 19.1% ± 16.6%). At 1 month, 21 (3.8%) MACE and 29 (5.5%) bleedings ≥ 2 according to the Bleedings Academic Research Consortium (BARC) scale were recorded. Neither MACE nor bleeding was associated with PR (P = .34 and P = .78, respectively). However, there was a strong association between PR and the occurrence of definite acute stent thrombosis (P = .03). Platelet reactivity was the only factor associated with acute definite stent thrombosis.

CONCLUSION

In patients receiving a ticagrelor LD while undergoing PCI for ACS, PR using the VASP did not predict MACE or bleeding, but it was significantly associated with the occurrence of definite acute stent thrombosis.

Ticagrelor versus prasugrel in diabetic patients with an acute coronary syndrome. A pharmacodynamic randomised study

Optimal P2Y12 receptor blockade is critical to prevent ischaemic recurrence in patients undergoing percutaneous coronary intervention (PCI). We aimed to compare the level of platelet reactivity (PR) inhibition achieved by prasugrel and ticagrelor loading dose (LD) in diabetic acute coronary syndrome (ACS) patients undergoing PCI. We performed a single-center prospective open-label randomised trial. Patients with diabetes mellitus undergoing PCI for an ACS were randomised to receive prasugrel 60 mg or ticagrelor 180 mg. The primary endpoint of the study was the level of platelet reactivity (PR) assessed between 6 and 18 hours post-LD using the VASP index. We randomised 100 diabetic patients undergoing PCI for an ACS. No difference was observed in baseline characteristics between the two groups. In particular, the rate of patient receiving insulin therapy was identical (25 vs 28.6%; p =0.7). Ticagrelor achieved a significantly lower PR compared to prasugrel loading dose (17.3 ± 14.2 vs 27.7 ± 23.3%; p=0.009). In addition the rate of high on-treatment platelet reactivity, defined by a VASP ≥50%, tend to be lower in the ticagrelor group although the difference did not reach statistical significance (6 vs 16%; p=0.2). The rate of low on treatment PR was identical (60 vs 54%; p=0.8). The present study demonstrates that ticagrelor LD is superior to prasugrel LD to reduce PR in ACS patients with diabetes mellitus. Whether the higher potency of ticagrelor could translate into a clinical benefit should be investigated.