Add-on Cangrelor in STEMI-triggered Cardiac Arrest

Neurologic damage after cardiac arrest is frequent and therapeutic options to improve neurological outcome are limited. Treatment by therapeutic hypothermia (TH, 32-34◦C) for 12-24 h showed improved neurological outcome in several trials. Therefore, international guidelines recommend targeted temperature management (TTM) to 32-34◦C (or at least 36°C) for 12-24 h, especially when the initial rhythm was ventricular fibrillation.

However, patients treated with TTM after cardiac arrest show deteriorated and delayed response to P2Y12 receptor (P2Y12r) inhibitors as determined by platelet reactivity index vasodilator-stimulated phosphoprotein phosphorylation (PRI VASP) after administration of the loading dose of clopidogrel, prasugrel and ticagrelor. Especially the response to clopidogrel is poor with up to >80% non-responder after 24 hours. Impaired P2Y12r blockade may lead to acute stent-thrombosis and trigger overall adverse outcome.

There are several explanations for the impaired efficacy of P2Y12r inhibitors in cardiac arrest patients. First, marketed oral P2Y12r inhibitors have to be applied in crushed form via nasogastric tube in comatose post cardiac arrest patients. Placement of nasogastric tube and crushing may delay onset of therapy. Second, drug uptake and bioavailability of oral P2Y12r inhibitors are dependent on gastric motility and sufficient splanchnic blood supply, which is affected by TTM, acute critical illness (shock) and concomitant therapy. Particularly, sedation and analgesic agents, especially concomitant morphine therapy, can hamper gastric emptying. Various recent trials demonstrated that morphine administration delays and attenuates clopidogrel, prasugrel and ticagrelor exposure and action in healthy subjects and patients with myocardial infarction.

The recently authorized parenteral cangrelor is an adenosine triphosphate (ATP) analogue that binds reversibly and with high affinity to the platelet P2Y12r. It induces a highly effective inhibition of ADP-induced platelet aggregation immediately after intravenous (iv) bolus administration and allows for restoration of platelet function within 1-2 h of infusion discontinuation. The pharmacokinetic properties known so far suggest cangrelor being the "ideal" P2Y12r inhibitor for patients with cardiac-ischemia triggered OHCA treated with TH and may overcome the impaired and delayed P2Y12r blockade seen with the oral P2Y12r inhibitors.

Cardiac arrest is a leading cause of death among adults over the age of 40 in the European Union (EU) and other western countries. In the EU alone, more than 400.000 people of all ages experience EMS-assessed out-of-hospital non-traumatic cardiac arrest each year and most of them die. In a large proportion of these patients (about 50%) an acute coronary syndrome (ACS), mainly acute ST-elevation myocardial infarction, leading to ventricular fibrillation and cardiac standstill is the cause of the cardiac arrest. Various trials demonstrated that early cardiac intervention including stent placement to the culprit lesion improves outcome in this patient group. The P2Y12r plays a central role in platelet activation and P2Y12r inhibitors are part of standard care in patients with ACS. Delayed and insufficient P2Y12r inhibition may predispose to acute stent thrombosis with potential devastating effects including cardiogenic shock, re-arrest and death. Given the deteriorated and delayed response to oral P2Y12r inhibitors in cardiac arrest patients treated with TH, clinical evaluation of the recently marketed parenteral P2Y12r inhibitor cangrelor is mandatory in this patient group.

To determine the effect of add-on cangrelor in STEMI-associated out-of-hospital cardiac arrest (OHCA) who receive TTM and are scheduled for PCI, a phase 4 trial will be conducted.The trial consists of 2 parts. Part A (n=12, 8months duration): An open-fashioned pilot safety-study to ensure sufficient platelet suppression (<466AU*min, impedance aggregometry) over 24 hours after concurrent cangrelor-prasugrel/ticagrelor administration. The aim is to determine pharmacokinetics and -dynamics of oral P2Y12r-inhibitors with and without concomitant administration of cangrelor. Part B (n=48, 32months duration): A factorial randomized, placebo-controlled, double-blind study with 4 study cohorts enrolling 48 patients who will first be randomised to receive prasugrel (n=24) or ticagrelor (n=24) and secondly to additionally receive cangrelor or placebo (sterile saline). Primary endpoint: ADP-dependent platelet reactivity at time of stent placement (AU*min). Student's t-test to test H0 (no difference in AU*min, cangrelor vs placebo).