A 67-year-old male patient with a history of hypertension and type 2 diabetes mellitus presents to the emergency department with sudden onset chest pain that began while he was mowing his lawn. His only home medications are hydrochlorothiazide 25 mg taken once daily and metformin 500 mg taken twice daily. Upon arrival to the emergency department, his blood pressure is 135/88 mmHg, and his heart rate is 95 bpm. He appears to be in mild discomfort, but his physical exam is otherwise unremarkable. His electrocardiogram shows sinus rhythm with anterior ST segment depressions, and his initial troponin I level is 1.2 ng/ml. His chest pain persists despite two doses of sublingual nitroglycerin, so he is started on a nitroglycerin infusion, and the decision is made to proceed with a coronary angiogram. The patient receives 325 mg of chewable aspirin and is transferred to the cardiac catheterization laboratory. Coronary angiography reveals a 90% occlusion of his mid left anterior descending that is associated with thrombus. He is started on a cangrelor infusion, and a drug-eluting stent is then placed across the lesion, resulting in normal flow. His chest pain subsequently resolves. The patient tolerates the procedure well, and there are no immediate complications. The cangrelor is discontinued after a total infusion time of 2 hours.
In addition to a daily dose of 81 mg of aspirin, which of the following is an acceptable strategy for oral antiplatelet therapy?
Show Answer
The correct answer is: B. Ticagrelor 180 mg given 1 hour prior to discontinuation of the cangrelor infusion, followed by 90 mg twice daily
Cangrelor is an intravenous formulation of a P2Y12 inhibitor approved by the Food and Drug Administration in 2015 for use in prevention of thrombosis during percutaneous coronary interventions in patients who have not been treated with a P2Y12 inhibitor and who will not receive a glycoprotein IIb/IIIa inhibitor. Dosing instructions call for an infusion of at least 2 hours or for the duration of the intervention, whichever is longer.1 Off-label use as a bridge to surgery in patients presenting with an acute coronary syndrome who are awaiting coronary artery bypass grafting has also been described.2,3 Once the patient is able to take oral medication, he or she can be transitioned to an oral P2Y12 inhibitor. Clopidogrel and prasugrel should be started immediately upon discontinuation of the cangrelor infusion, and ticagrelor can be started either during the infusion or immediately upon its discontinuation. Regardless of which medication is chosen, the first dose should be a loading dose (600 mg for clopidogrel, 180 mg for ticagrelor, and 60 mg for prasugrel), which is then followed by standard dosing.1 Of the possible answers, only answer B presents the correct dosing and timing of administration.
Roffi M, Patrono C, Collet JP, et al. 2015 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: Task Force for the Management of Acute Coronary Syndromes in Patients Presenting without Persistent ST-Segment Elevation of the European Society of Cardiology (ESC). Eur Heart J 2016;37:267-315.
Angiolillo DJ, Firstenberg MS, Price MJ, et al. Bridging antiplatelet therapy with cangrelor in patients undergoing cardiac surgery: a randomized controlled trial. JAMA 2012;307:265-74.
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