Question 1

A 53-year-old black man presents to the emergency department with a complaint of chest pain of 2 hours' duration. The pain woke him from sleep. It is substernal and radiates to his left shoulder. The patient has vomited twice and is diaphoretic. He has no history of coronary artery disease but has hypertension and hypercholesterolemia.

Please choose the single most appropriate answer to the question

1. The presence of a severe stenosis (i.e., a stenosis ³ 70% of the diameter of the artery), as seen on coronary angiography, correlates well with the most vulnerable sites for plaque rupture and occlusion of the coronary artery
   
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   Key Concept/Objective: To understand the basic pathophysiology and the initial treatment of acute myocardial infarction

   
   

   Although to produce anginal symptoms, a stenosis of a coronary artery must be severe (i.e., ³ 70% of the diameter of the artery), such stenoses tend to have dense fibrotic caps and are less prone to rupture than mild to moderate stenoses, which are generally more lipid laden. Studies of patients in whom angiography was performed before and after a myocardial infarction revealed that in most cases, acute coronary occlusion occurred at sites in the coronary circulation with stenoses of less than 70%, as demonstrated on the preinfarction angiogram. A patient with symptoms suggestive of myocardial infarction should be evaluated within 10 minutes after arrival in the emergency department. Early steps should include the assessment of hemodynamic stability by measurement of the patient's heart rate and blood pressure; the performance of a 12-lead ECG; and the administration of oxygen by nasal prongs, of I.V. analgesia (most commonly morphine sulfate), of oral aspirin, and of sublingual nitroglycerin if the blood pressure is greater than 90 mm Hg.
   
   

   
   
   
2. Within 10 minutes of arrival at the emergency department, a patient with symptoms suggestive of a myocardial infarction should be evaluated; subsequently, the patient should be evaluated with a 12-lead electrocardiogram, and oxygen and aspirin should be administered
   
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3. Morphine sulfate is acceptable for pain control in a patient with an acute myocardial infarction
   
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4. In the second International Study of Infarct Survival (ISIS-2) trial, aspirin was found to be nearly as effective as streptokinase in reducing 30-day mortality
   
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Question 2

A 62-year-old white woman with a history of coronary artery disease presents to the emergency department with substernal, squeezing chest tightness of 2 hours' duration. The pain is identical to the pain she experienced with her first myocardial infarction. On physical examination, the patient's heart rate is found to be 105 beats/min; a tachycardic regular rhythm without gallop is noted. The patient's lung fields are clear. A chest radiograph is normal, but ECG reveals ST segment elevation in leads I, aVL, V5, and V6.

Please choose the single most appropriate answer to the question

1. Thrombolytic therapy has been studied in patients with ECG findings other than ST-segment elevation or bundle branch block and has been found to be superior to conventional therapy
   
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2. Current recommendations are that the time between a patient's presentation to the emergency department and the administration of thrombolytic therapy not exceed 2 hours
   
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3. Coronary angiography is recommended in all patients after thrombolytic therapy has been administered, once they become hemodynamically stable
   
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4. Streptokinase therapy is contraindicated in patients who have recently received a dose of streptokinase because of antibodies that form against the drug
   
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   Key Concept/Objective: To understand the basic principles of thrombolytic therapy

   
   

   The time between a patient's presentation to the emergency department and the administration of thrombolytic therapy should not exceed 60 minutes. Front-loaded tissue plasminogen activator (t-PA) has been found to be superior to the other thrombolytic regimens. However, some physicians prefer the less expensive streptokinase therapy, particularly for patients at low risk of dying (e.g., those with uncomplicated inferior infarctions) and the elderly, who are more likely to have hemorrhagic complications with t-PA than with streptokinase. Streptokinase is contraindicated in patients who have recently received a dose of streptokinase because of antibodies that form against the drug; these antibodies limit the efficacy of repeat doses and increase the risk of allergic reactions. Thrombolytic therapy has been studied in patients with ECG findings other than ST-segment elevation or bundle branch block and has been found to be either of no use or deleterious. Patients treated with thrombolytic therapy in whom complications do not occur are at low risk for reinfarction and death after discharge, and routine performance of coronary angiography and coronary angioplasty does not reduce the occurrence of these adverse events. Coronary angiography is recommended only for patients with hemodynamic instability or for patients in whom spontaneous or exercise-induced ischemia occurs.
   
   

   
   
   

Question 3

A 49-year-old white man who presented to the emergency department with an ST-segment elevation myocardial infarction was given thrombolytics, oxygen, and aspirin. He is now free of chest pain and will be admitted to the coronary care unit for further monitoring.

Please choose the single most appropriate answer to the question

1. Early administration of beta blockers reduces the mortality and the reinfarction rate
   
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2. Unless contraindicated, angiotensin-converting enzyme (ACE) inhibitors are indicated in patients with significant ventricular dysfunction after acute myocardial infarction
   
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3. When given within 6 hours after presentation to the hospital, I.V. nitroglycerin reduces mortality in patients with myocardial infarction
   
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   Key Concept/Objective: To understand the adjuvant medical therapies available for patients with acute myocardial infarction after reperfusion therapy has been administered

   
   

   Early administration of beta blockers may reduce infarct size by reducing heart rate, blood pressure, and myocardial contractility. It is recommended that all patients with acute myocardial infarction without contraindications receive I.V. beta blockers as early as possible, whether or not they receive reperfusion therapy. Several large, randomized, controlled clinical trials evaluated the use of ACE inhibitors early after acute myocardial infarction; all but one trial revealed a significant reduction in mortality. To determine whether nitroglycerin therapy is beneficial in patients treated with reperfusion, 58,050 patients with acute myocardial infarction in the ISIS-4 trial were randomized to receive either oral controlled-release mononitrate therapy or placebo; thrombolytic therapy was administered to patients in both groups. The results of this study revealed no benefit from the routine administration of oral nitrate therapy in this setting. Previously, routine prophylactic antiarrhythmic therapy with I.V. lidocaine was recommended for all patients in the early stages of acute myocardial infarction. However, studies have revealed that prophylactic therapy with lidocaine does not reduce and may actually increase mortality because of an increase in the occurrence of fatal bradyarrhythmia and asystole.
   
   

   
   
   
4. Prophylactic therapy with lidocaine does not reduce and may actually increase mortality because of an increase in the occurrence of fatal bradyarrhythmia and asystole
   
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Question 4

A 49-year-old white woman was admitted last night with an acute ST-segment elevation myocardial infarction. She underwent left heart catheterization with restoration of blood flow to her left circumflex artery and is currently in the CCU. She has received anticoagulation therapy and has been started on an ACE inhibitor, aspirin, and a beta blocker.

Please choose the single most appropriate answer to the question

1. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial showed that rhythm-control strategies provided a significant survival advantage when compared with rate-control strategies
   
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2. Beta blockers may reduce the early occurrence of ventricular fibrillation
   
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   Key Concept/Objective: To know the complications associated with acute myocardial infarction

   
   

   Although lidocaine has been shown to reduce the occurrence of primary ventricular fibrillation, mortality in patients receiving lidocaine was increased because of an increase in fatal bradycardia and asystole, and prophylactic lidocaine is no longer recommended if defibrillation can rapidly be performed. Beta blockers may reduce the early occurrence of ventricular fibrillation and should be administered to patients who have no contraindications. The treatment of atrial fibrillation in acute myocardial infarction should be similar to the treatment of atrial fibrillation in other settings. If atrial fibrillation recurs, antiarrhythmic agents may be used, although their impact on clinical outcomes is unproven. Mild mitral regurgitation is common in acute myocardial infarction and is present in nearly 50% of patients. The posterior papillary muscle receives blood only from the dominant coronary artery (the right coronary artery in nearly 90% of patients); thrombotic occlusion of this artery may cause rupture of the posterior papillary muscle, resulting in severe mitral regurgitation. Although nearly all patients with right ventricular infarction suffer both right and left ventricular infarction, the characteristic hemodynamic findings of right ventricular infarction generally dominate the clinical course and must be the main focus of therapy.
   
   

   
   
   
3. Severe mitral regurgitation is 10 times more likely to occur with anterior myocardial infarction than with inferior myocardial infarction
   
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4. When patients have right ventricular infarction, the left ventricle is almost always spared of any damage
   
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