Ticagrelor treatment resulted in rapid and profound reduction in platelet reactivity compared with clopidogrel in low-risk troponin-negative patients with acute coronary syndromes (ACS) who are undergoing elective or non-urgent ad hoc percutaneous coronary intervention (PCI). Roxana Mehran, MD, Mount Sinai Hospital, New York, New York, USA, presented data from an ad hoc PCI study in ACS patients [NCT01603082].

Ticagrelor is a potent P2Y₁₂-receptor inhibitor that is currently approved by the FDA for the treatment of patients with ACS. However, patients with low-risk ACS who are troponin-negative and undergo elective or non-urgent PCI may not receive a loading dose of a P2Y₁₂ receptor inhibitor prior to catheterization. The purpose of this study was to evaluate the effect of ticagrelor on platelet reactivity in patients with troponin-negative ACS undergoing ad hoc PCI who receive a loading dose in the catheterization laboratory immediately prior to PCI.

In this prospective, open-label, multicenter, phase 4 trial, 100 patients were randomly assigned to receive ticagrelor or clopidogrel. Patients in the ticagrelor arm (n = 51) received a 180-mg loading dose after diagnostic angiography followed by 90 mg 12 hours later. Patients in the clopidogrel arm (n = 49) received a 600-mg loading dose after diagnostic angiography. All patients received a 160- to 500-mg loading dose of aspirin followed by 75 to 100 mg of aspirin daily. Patients with ACS and ≥ 1 negative troponin test 6 to 48 hours after symptom onset were included in the study. Patients who used thienopyridine or ticagrelor within 7 days of randomization, had an indication for chronic anticoagulation, or concomitant therapy with a strong CYP3A inhibitor, substrates, or inducers were excluded.

The primary end point was platelet reactivity 2 hours after dosing of the study drug, which was measured by P2Y₁₂ reaction unit (PRU) level by the VerifyNow system. Secondary end points included PRU levels at 30 min after dosing, end of PCI, and 8 hours after dosing; percent reduction from baseline in PRU levels; and percent inhibition of platelet aggregation from baseline.

Patients who received ticagrelor demonstrated a significantly lower mean PRU level 2 hours after their loading dose compared with patients who received clopidogrel (treatment difference, −159.1; 95% CI, −194.7 to −123.5; P < .001). The significant difference in mean PRU levels occurred at the end of PCI and continued up to 8 hours following the loading dose of ticagrelor (P < .001; Figure 1). In addition, there was a significantly greater decrease in the reduction of PRU from baseline beginning at 2 hours after the loading dose compared with clopidogrel over the 8 hours (P < .001). Furthermore, inhibition of platelet aggregation was significantly greater in the ticagrelor arm compared with the clopidogrel arm across all time points.

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Figure 1.

Mean PRU Level After Treatment With Ticagrelor

LD, loading dose; PCI, percutaneous coronary intervention; PRU, platelet reaction units.

Reproduced with permission from R Mehran, MD.

The most common adverse events included chest pain, unstable angina, hypotension, dyspnea, and hematoma. Bleeding occurred in 5.9% of patients in the ticagrelor arm and 0 in the clopidogrel arm and all events were considered to be mild.

In conclusion, Dr Mehran stated that the data from this trial suggest that low-risk patients with troponin-negative ACS undergoing ad hoc PCI experienced greater platelet reactivity with ticagrelor treatment compared with clopidogrel.