This patient with chest pain and diaphoresis has ECG changes consistent with a lateral ST elevation myocardial infarction (STEMI).  Emergency reperfusion by percutaneous coronary intervention (PCI) or fibrinolysis in STEMI patients can reduce mortality and salvage ischemic myocardium.  PCI is preferred due to lower rates of hemorrhage and recurrent MI; however, it may not be available at all institutions.  In such cases, early treatment with fibrinolytics, namely recombinant forms of tissue plasminogen activator (eg, tenecteplase, alteplase), improves clinical outcomes.

Fibrinolytics bind fibrin and convert plasminogen to plasmin, which then hydrolyzes key bonds in the fibrin matrix, causing clot lysis and restoration of coronary arterial blood flow.  Intracerebral hemorrhage (ICH) is the most devastating adverse effect of fibrinolytic therapy; contraindications include prior stroke (especially hemorrhagic), intracranial neoplasm/vascular malformation, recent head trauma, and severe uncontrolled hypertension.  A sudden change in neurologic status following treatment with fibrinolytics should raise suspicion for ICH.

This patient's loss of consciousness, asymmetric pupils, and irregular breathing are likely due to hemorrhage-induced mass effect and increased intracranial pressure on the midbrain, oculomotor nerve (CN III), and brainstem respiratory center, respectively.  These findings are consistent with impending brain herniation, a life-threatening emergency requiring neurosurgical intervention.

(Choice A)  Carotid artery thrombosis can cause cerebral ischemia resulting in neurologic deficits.  However, focal deficits (eg, hemiparesis) rather than global deficits (eg, comatose state) are typically present.  In addition, a hemorrhagic complication is more likely than a thrombotic event following fibrinolytic administration.

(Choice B)  Aortic dissection can present with chest pain and focal neurologic deficits (due to extension of dissection into the carotid/intercostal arteries).  However, the chest pain classically radiates to the back and other risk factors (eg, hypertension, connective tissue disorder) are often present.  In addition, this patient's constellation of neurologic findings is more characteristic of brain herniation.

(Choices C and E)  Interventricular septum perforation is a mechanical complication of MI that presents with heart failure (eg, cardiogenic shock).  Myocardial reperfusion injury (causing cardiomyocyte dysfunction from reperfusion of ischemic tissue) is a potential complication of fibrinolysis that may manifest with heart failure or ventricular arrhythmia.  Neither of these conditions would explain this patient's asymmetric pupils.

(Choice F)  Pulmonary embolism (PE) presents with acute-onset dyspnea, tachycardia, and pleuritic chest pain.  Hypotension and loss of consciousness can occur with a large PE, but asymmetric pupils would not be expected.

Educational objective:
Fibrinolytic therapy for acute ST-segment elevation myocardial infarction improves clinical outcomes when percutaneous coronary intervention is unavailable.  A life-threatening complication of fibrinolytic therapy is intracerebral hemorrhage, which should be suspected in a patient with acute neurologic deterioration.