Coronary artery disease is an important cause of out-of hospital cardiac arrest (OHCA) and around 80 % of patients after OHCA are comatose. Considering patient's history, details concerning OHCA and ECG changes the decision on urgent cardiac catheterization is made. In case of significant coronary artery stenosis/occlusion on primary percutaneous coronary intervention stent implantation is usually needed. Dual antiplatelet therapy is the cornerstone of stent thrombosis prevention. Patients who are comatose after the return of spontaneous circulation (ROSC) differ from conscious survivors of OHCA because they are not able to take antiplatelet drugs, such as P2Y12 inhibitors, orally. Due to the need for nasogastric/ orogastric tube insertion there is a significant delay until optimal antiplatelet effect is achieved. Furthermore, there are other factors that have an impact on the pharmacokinetics of P2Y12 inhibitors, such as therapeutic hypothermia, gastroparesis, gastrointestinal tract hypoperfusion and platelet hyperreactivity because of systemic inflammatory response syndrome. These characteristics make acute and subacute stent thrombosis more common in comatose OHCA survivors leading to increased morbidity and mortality.

Heparin is the primary anticoagulant drug for comatose patients after OHCA. Antiplatelet therapy consists of intravenous aspirin and P2Y12 inhibitor. Ticagrelor is the most potent of the latter. It is available only as a tablet, which has to be crushed and dissolved and then given via nasogastric or orogastric tube. A recent study by Steblovnik et al. has shown there is an approximately 4-hour gap of inadequate platelet inhibition in comatose OHCA even if the most potent P2Y12 inhibitor ticagrelor is used. Prueller made a retrospective study assessing the addition of intravenous P2Y12 inhibitor cangrelor as a bridge of this gap to standard care. The results showed there is a significant antiplatelet effect when using cangrelor with no added bleeding risk. After literature review no prospective randomised study has been done comparing cangrelor-bridge to standard care with dual antiplatelet therapy (aspirin and ticagrelor).

The investigator's study is a single-blinded, prospective randomised study taking place at University Medical Centre Ljubljana. Thirty comatose survivors of OHCA will be randomised at the start of primary PCI into a test and control group. The control group will receive standard care with intravenous aspirin and dissolved ticagrelor tablets given via enteral tube. The test group patients will receive an additional P2Y12 bridging therapy: a bolus of cangrelor at the start of the PCI (30 mcg/kg) followed by a continuous 4-hour infusion (4 mcg/kg/min). Heparin will be used as per guidelines for a target ACT of 250-300 seconds at the time of PCI. Interventional cardiologist will decide on the use of eptifibatide (GP IIb/IIIa antagonist). Therapeutic hypothermia will be started in the catheterisation laboratory. All patients will be transferred to ICU after the procedure and level of platelet inhibition will be tested 1, 3 and 5 hours after the start of cangrelor infusion with VerifyNow and Multiplate systems. In the control group blood will be drawn at the same time intervals. Further management of patients in both arms will be no different from regular care.