The impact of mild therapeutic hypothermia on platelet reactivity in comatose survivors of cardiac arrest with acute myocardial infarction treated with ticagrelor.

Background: The aim of the study was to assess the antiplatelet effect of ticagrelor in patients with myocardial infarction (MI) after out-of-hospital cardiac arrest (OHCA) treated with percutaneous coronary intervention (PCI) and mild therapeutic hypothermia (MTH) vs. MI patients without OHCA treated with PCI.

Methods: The study was designed and performed as a phase IV, single-center, investigator-initiated, prospective, observational study assessing the early pharmacodynamic effect (within first 24 h) of a ticagrelor loading dose (180 mg) in both groups of patients (MTH group vs. MI group). For assessment of ticagrelor pharmacodynamics Multiple Electrode Aggregometry (MEA) was applied.

Results: Compared with the MTH group, platelet inhibition was persistently stronger in the MI group over the entire observation period (up to 24 h), with the highest differesnce at 4 hours after loading with ticagrelor (25.8 ± 26.4 vs. 75.8 ± 40.9 U, p = 0.002). As a consequence, there was a higher prevalence of high platelet reactivity in the MTH group, with the most explicit difference at 6 hours after the loading dose of ticagrelor (78% vs. 7%, p < 0.001).

Conclusions: In comparison with patients treated with primary PCI for uncomplicated MI, the antiplatelet effect of ticagrelor in patients with MI complicated with OHCA, undergoing MTH and primary PCI, is attenuated and delayed.