A 65-year-old man is brought to the emergency department due to chest discomfort and diaphoresis that suddenly began an hour ago while he rested in a chair and watched television. The patient describes the discomfort as "squeezing"; it is associated with left arm numbness and nausea. En route to the hospital, he was given a chewable aspirin. The patient has never had similar symptoms and has no significant medical history. He has smoked a pack of cigarettes daily for the past 40 years. Temperature is 36.9 C (98.4 F), blood pressure is 165/95 mm Hg, pulse is 50/min, and respirations are 18/min. S1 and S2 are normal, and an S4 is heard. The lungs are clear to auscultation. ECG is shown in the exhibit. Interventions aimed at achieving which of the following goals would most improve this patient's long-term prognosis?
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This patient's chest pain, diaphoresis, arm numbness, nausea, and ECG findings of ST-segment elevation in leads II, III, and aVF are diagnostic of acute inferior ST-segment elevation myocardial infarction (STEMI), likely due to abrupt right coronary artery occlusion. Prompt restoration of coronary blood flow with percutaneous coronary intervention (PCI) or fibrinolysis limits myocardial damage and improves cardiovascular and overall long-term mortality.
Guidelines recommend the use of PCI for any patient with acute STEMI within 90 minutes of the first medical contact in a PCI-capable hospital or within 120 minutes for patients requiring transport to a PCI-capable hospital from another hospital. Multiple randomized trials of PCI compared to fibrinolysis have shown lower rates of recurrent MI and intracranial hemorrhage and improved survival with PCI.
(Choice A) There is no evidence of improved long-term outcomes with interventions aimed at decreasing cardiac afterload (eg, intraaortic balloon pump, hydralazine, nitroprusside) in patients with acute MI.
(Choice B) Early use of beta blockers decreases myocardial contractility (and heart rate) and can reduce myocardial oxygen demand in acute MI. However, in STEMI, beta blockers do not provide the same degree of benefit as urgent coronary reperfusion. This patient also has a pulse of 50/min and is at risk for worsening bradycardia with beta blocker therapy.
(Choice C) Routine prophylactic use of antiarrhythmic therapy to prevent atrial or ventricular arrhythmias in patients with acute MI does not improve long-term outcomes and is not recommended.
(Choice D) Reperfusion injury refers to the myocardial cell damage that occurs due to restoration of blood flow after a sudden ischemic event. No specific therapy has been shown to prevent reperfusion injury following acute MI.
Educational objective:
Prompt recognition and restoration of coronary blood flow with percutaneous coronary intervention or fibrinolysis improve cardiovascular and overall long-term mortality in patients with ST-segment elevation myocardial infarction.