Major heart attacks are caused by a number of factors, the two major of which are furring up of a coronary artery with atheroma and then sudden clot formation on this area leading to a blockage and interruption of blood flow. The clots that lead to heart attacks are largely made of clotting blood cells (platelets) that in health repair blood vessels and inhibit spontaneous bleeding. One of the main treatment strategies for heart attacks is to make these cells less "sticky". Aspirin is a main stay of anti-platelet treatment in the United Kingdom (UK) and in addition one of three other oral antiplatelet agents acting on the same platelet activation pathway (P2Y12 receptor) is licensed for use. When a patient is admitted with a major heart attack, they are treated with emergency primary percutaneous coronary intervention (PPCI) a technique where a wire and balloon are used to reopen the coronary artery and then usually a stent (a slotted metal tube) is placed to keep the artery open. Aspirin and one of the P2Y12 inhibitor agents are given to prevent further clots and all have been shown to reduce negative events following heart attacks and angioplasty with stent insertion. There are increasing data, including from our own institution, showing that in the setting of heart attacks, the oral P2Y12 inhibitors are poorly absorbed and have little effect at the time of most need, i.e. soon after dosing while the primary PCI is being performed. All three current P2Y12 inhibitor agents are taken in tablet form immediately before the emergency PPCI procedure. It appears that in healthy stable patients these agents take at least 30 min to 2 hours to have an adequate effect. In heart attack patients the angioplasty procedure is usually performed well within this timescale. Furthermore, patients who are having a heart attack do not have normal drug absorption with blood being diverted away from the stomach and gut activity being suppressed by other drugs such as morphine. In this current study, patients with major heart attacks will be given our standard oral agent, Ticagrelor, or the newer intravenous agent Cangrelor prior to PPCI.
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Degree of Platelet Inhibition Measured
Timeframe: Measured at 4, 24 and 36 hours post dosing