A 72-year-old presents with sudden-onset chest pain at a local emergency department. He has a past medical history significant for hypertension, hyperlipidemia, and gastroesophageal reflux disease. On examination his BP is 95/60 mmHg and heart rate is 90 beats per minute and he is breathing at 90% on ambient air. He reports this is the first time he has had any episode of chest pain. His electrocardiogram (ECG) reveals ST elevation in V1 to V4 . The nearest hospital with percutaneous coronary intervention (PCI) capability is 3 hours away.
What is the next step in management?
Fibrinolysis; low-molecular-weight heparin (LMWH), aspirin, and clopidogrel; and transfer to hospital for possible PCI. This patient has acute STEMI. Current ACC/AHA guidelines recommend (class I) administration of fibrinolytic therapy (within 30 minutes) when there is an anticipated delay to performing primary PCI within 120 minutes of first medical contact. In addition to fibrinolysis, adjunctive antiplatelet therapy (aspirin 162 to 325 mg loading dose and clopidogrel 300 mg loading dose in patients aged <75 years) and antithrombotic therapy (weight-adjusted unfractionated heparin or LMWH) should be promptly initiated. Adjunctive LMWH in the setting of fibrinolysis was compared with heparin in the randomized ENTIRE-TIMI-23 trial. The study showed reduced ischemic events (death/recurrent MI) with LMWH when compared with unfractionated heparin at 30 days (4.4% versus 15.9%). The benefit of early routine angiography regardless of symptom status and hemodynamic stability has been confirmed in a number of clinical trials. As a result, transfer to a PCI hospital following lytic administration is encouraged.
The patient is given intravenous tenecteplase and started on aspirin, clopidogrel, and unfractionated heparin. Thirty minutes into treatment his chest pain has now completely resolved. A repeat ECG shows complete resolution of the earlier noted ST elevation.
Continue unfractionated heparin, aspirin, and clopidogrel and transfer to the nearest hospital with PCI capabilities. Repeat ECG reveals resolution of ST-segment elevation that likely indicates reperfusion. As previously stated, a significant proportion of patients receiving fibrinolysis may undergo reocclusion of the infarct artery. Therefore, it is reasonable to transfer patients to the nearest PCI-capable hospital (ACC/AHA class IIa recommendation). Angiography 3 to 24 hours after fibrinolysis is now recommended in these subjects regardless of hemodynamic status. Discharge home after stress test and referral for delayed angiography are not preferred options for patients with acute STEMI treated with fibrinolysis.
Which of the following is true for management of acute STEMI?
Streptokinase and aspirin each have a similar effect on outcome. Based on results of International Studies of Infarct Survival (ISIS-2) trial from the fibrinolytic era, aspirin provides as much mortality benefit as streptokinase and the combination provides additive benefit in acute MI.
Which of the following is the mechanism of action of ticagrelor?
Adenosine diphosphate blockade. Ticagrelor reversibly blocks adenosine diphosphate receptors of subtype P2Y12 on platelet cell membranes eventually leading to inhibition of platelet activation. Aspirin acts by a thromboxane inhibition and abciximab is a chimeric human monoclonal antibody that works by blockade of the activated GP II/IIIa receptor on the platelet surface.
Which of the following is true regarding use of GP IIb/IIIa inhibitors in STEMI?
Routine GP IIb/IIIa inhibitor use is associated with increased risk of bleeding. While prior studies documented benefits of routine intravenous GP IIb/IIIa in STEMI, the emergence of potent platelet adenosine diphosphate P2Y12 receptor inhibitors sparked controversy regarding their additive benefit. Most subsequent trials demonstrated no clinical benefit with possible increased risk of bleeding with routine use of these agents in addition to dual oral antiplatelet therapy. A benefit for upstream GP IIb/IIIa inhibition was also not evident in the Early Glycoprotein IIb/IIIa Inhibition in Non–ST-Segment Elevation Acute Coronary Syndrome (EARLY ACS) and Acute Catheterization and Urgent Intervention Triage strategY (ACUITY) trials. Use of these agents is now reserved in the catheterization laboratory for patients undergoing high-risk PCI with high thrombus burden and for bailout.
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