A 28-year-old male presents with sharp, stabbing chest pain that worsens when lying flat and improves when sitting forward. He reports a recent viral upper respiratory infection 2 weeks ago. On examination, a friction rub is heard on auscultation. His vital signs are stable. An ECG is most likely to show which of the following findings in this patient?

Diffuse, concave ST-segment elevations

Peaked T waves and ST-segment elevations in leads V1-V6

S waves in lead I, Q waves in lead III, and inverted T waves in lead III

Alternating high and low amplitude QRS complexes

A 71-year-old man develops worsening chest pressure while shoveling snow in the morning. He tells his wife that he has a squeezing pain that is radiating to his jaw and left arm. His wife calls for an ambulance. On the way, he received chewable aspirin and 3 doses of sublingual nitroglycerin with little relief of pain. He has borderline diabetes and essential hypertension. He has smoked 15–20 cigarettes daily for the past 37 years. His blood pressure is 172/91 mm Hg, the heart rate is 111/min and the temperature is 36.7°C (98.0°F). On physical examination in the emergency department, he looks pale, very anxious and diaphoretic. His ECG is shown in the image. Troponin levels are elevated. Which of the following is the best next step in the management of this patient condition?

Clopidogrel, atenolol, anticoagulation and monitoring

CT scan of the chest with contrast

A 54-year-old man is brought to the emergency department 1 hour after the sudden onset of shortness of breath, severe chest pain, and sweating. He has hypertension and type 2 diabetes mellitus. He has smoked one pack and a half of cigarettes daily for 20 years. An ECG shows ST-segment elevations in leads II, III, and avF. The next hospital with a cardiac catheterization unit is more than 2 hours away. Reperfusion pharmacotherapy is initiated. Which of the following is the primary mechanism of action of this medication?

Conversion of plasminogen to plasmin

Inhibition of glutamic acid residue carboxylation

Blocking of adenosine diphosphate receptors

Direct inhibition of thrombin activity

Prevention of thromboxane formation

A 66-year-old female with hypertension and a recent history of acute ST-elevation myocardial infarction (STEMI) 6 days previous, treated with percutaneous transluminal angioplasty (PTA), presents with sudden onset chest pain, shortness of breath, diaphoresis, and syncope. Vitals are temperature 37°C (98.6°F), blood pressure 80/50 mm Hg, pulse 125/min, respirations 12/min, and oxygen saturation 92% on room air. On physical examination, the patient is pale and unresponsive. Cardiac exam reveals tachycardia and a pronounced holosystolic murmur loudest at the apex and radiates to the back. Lungs are clear to auscultation. Chest X-ray shows cardiomegaly with clear lung fields. ECG is significant for ST elevations in the precordial leads (V2-V4) and low-voltage QRS complexes. Emergency transthoracic echocardiography shows a left ventricular wall motion abnormality along with a significant pericardial effusion. The patient is intubated, and aggressive fluid resuscitation is initiated. What is the next best step in management?

Immediate transfer to the operating room

Immediate cardiac catheterization

Intra-aortic balloon counterpulsation

Administer dobutamine 5-10 mcg/kg/min IV

A 52-year-old woman presents to the emergency room complaining of chest pain. She reports a 4-hour history of dull substernal pain radiating to her jaw. Her history is notable for hypertension, diabetes mellitus, and alcohol abuse. She has a 30 pack-year smoking history and takes lisinopril and metformin but has an allergy to aspirin. Her temperature is 99.1°F (37.3°C), blood pressure is 150/90 mmHg, pulse is 120/min, and respirations are 22/min. Physical examination reveals a diaphoretic and distressed woman. An electrocardiogram reveals ST elevations in leads I, aVL, and V5-6. She is admitted with plans for immediate transport to the catheterization lab for stent placement. What is the mechanism of the next medication that should be given to this patient?

Vitamin K epoxide reductase inhibitor

A 71-year-old woman with a past medical history of type 2 diabetes, hypercholesterolemia, and hypertension was admitted to the hospital 8 hours ago with substernal chest pain for management of acute non-ST-elevated myocardial infarction (NSTEMI). The ECG findings noted by ST-depressions and T-wave inversions on anterolateral leads, which is also accompanied by elevated cardiac enzymes. Upon diagnosis, management with inhaled oxygen therapy, beta-blockers and aspirin, and low-molecular-weight heparin therapy were initiated, and she was placed on bed rest with continuous electrocardiographic monitoring. Since admission, she required 2 doses of sublingual nitroglycerin for recurrent angina, and the repeat troponin levels continued to rise. Given her risk factors, plans were made for early coronary angiography. The telemetry nurse calls the on-call physician because of her concern with the patient's mild confusion and increasing need for supplemental oxygen. At bedside evaluation, The vital signs include: heart rate 122/min, blood pressure 89/40 mm Hg, and the pulse oximetry is 91% on 6L of oxygen by nasal cannula. The telemetry and a repeat ECG show sinus tachycardia. She is breathing rapidly, appears confused, and complains of shortness of breath. On physical exam, the skin is cool and clammy and appears pale and dull. She has diffuse bilateral pulmonary crackles, and an S3 gallop is noted on chest auscultation with no new murmurs. She has jugular venous distention to the jaw-line, rapid and faint radial pulses, and 1+ dependent edema. She is immediately transferred to the intensive care unit for respiratory support and precautions for airway security. The bedside sonography shows abnormal hypodynamic anterior wall movement and an ejection fraction of 20%, but no evidence of mitral regurgitation or ventricular shunt. The chest X-ray demonstrates cephalization of pulmonary veins and pulmonary edema. What is the most appropriate next step in the stabilization of this patient?

Initiate dopamine therapy and diuresis

Obtain blood cultures and start preliminary broad-spectrum antibiotics

Start intravenous fluids and epinephrine therapy

Intubate the patient and perform an emergency cardiocentesis

Insert two large-bore intravenous catheters and start rapid fluid resuscitation

A 70-year-old man presents to the emergency department with severe substernal chest pain of one hour’s duration. The patient was taking a morning walk when the onset of pain led him to seek care. His past medical history includes coronary artery disease, hyperlipidemia, and hypertension. Medications include aspirin, losartan, and atorvastatin. An electrocardiogram reveals ST elevations in the inferior leads II, III, and avF as well as in leads V5 and V6. The ST elevations found in leads V5-V6 are most indicative of pathology in which of the following areas of the heart?

Lateral wall of left ventricle, left circumflex coronary artery

Left atrium, left main coronary artery

Inferior wall, right coronary artery

Interventricular septum, left anterior descending coronary artery

Right ventricle, right coronary artery

STEMI diagnosis and management for USMLE Step 3: High-Yield Internal Medicine Lessons

STEMI Diagnosis - Spotting the Enemy

ECG within 10 minutes of first medical contact is critical.
Diagnostic Criteria: ST-segment elevation in ≥2 contiguous leads.
- ≥1 mm in most leads.
- V2-V3: ≥2 mm (men ≥40), ≥2.5 mm (men <40), ≥1.5 mm (women).
- New or presumed new LBBB with ischemic symptoms is a STEMI equivalent.
Cardiac Biomarkers: ↑ Troponin I or T (highly sensitive/specific).

⭐ Posterior Wall MI: Often missed! Look for ST depression in V1-V3 (reciprocal changes). Confirm with ST elevation in posterior leads (V7-V9).

Acute Management - First Response

Immediate Actions: 12-lead ECG within 10 min, establish IV access, cardiac monitoring, O₂ if SpO2 <90%.
Initial Medical Therapy:
- Aspirin 325 mg (chewed) & P2Y12 inhibitor (e.g., ticagrelor).
- Nitroglycerin (sublingual/IV). ⚠️ Caution in RV MI, hypotension, or severe aortic stenosis.
- Morphine for refractory chest pain.
- Anticoagulation (unfractionated heparin or LMWH).

⭐ The cornerstone of STEMI care is timely reperfusion. The target for primary PCI is a door-to-balloon time of < 90 minutes.

Reperfusion Therapy - Opening the Gates

Primary Percutaneous Coronary Intervention (PCI) is the gold standard. The choice between PCI and fibrinolysis is critically time-dependent, aiming to restore coronary blood flow immediately.

PCI (Angioplasty with Stent): Preferred strategy.
- Goal: First Medical Contact (FMC) to device time < 90 minutes in a PCI-capable hospital.
- If transfer needed, FMC-to-device < 120 minutes.
Fibrinolysis (tPA, tenecteplase):
- Use if timely PCI is unavailable.
- Goal: Door-to-needle time < 30 minutes.
- ⚠️ Contraindicated in patients with prior intracranial hemorrhage or active bleeding.

Coronary Artery Angioplasty with Stent Placement

⭐ All patients receiving fibrinolysis should be transferred to a PCI-capable center for routine angiography and potential intervention within 3-24 hours.

Post-MI Care - The Long Road Back

Goal: Prevent reinfarction, manage complications, and improve long-term survival.
Secondary Prevention Medications (Post-MI Cocktail):
- Dual Antiplatelet Therapy (DAPT): Aspirin (lifelong) + P2Y12 inhibitor (e.g., clopidogrel) for at least 12 months.
- Beta-Blockers: Continue for ≥3 years; lifelong if HF or LVEF <40%.
- High-Intensity Statins: Atorvastatin 80 mg or Rosuvastatin 40 mg for all.
- ACE Inhibitors / ARBs: Especially with anterior MI, HF, or LVEF <40%.
- Aldosterone Antagonists: (e.g., spironolactone) if LVEF <40% with HF symptoms or diabetes.
Lifestyle is Key:
- Cardiac rehabilitation, smoking cessation, diet, exercise.
Complication Watchlist:
- Arrhythmias: ↑VT/VF risk. Consider ICD if LVEF <35% after 40 days.
- Pericarditis: Early vs. late (Dressler's).
- Structural: Aneurysm, mural thrombus, rupture.

⭐ Dressler Syndrome: Autoimmune pericarditis occurring weeks to months post-MI. Presents with fever, pleuritic chest pain, and a friction rub. Treat with NSAIDs/colchicine.

Classic symptom: Substernal chest pain radiating to the jaw/arm; be aware of atypical presentations (women, diabetics).

ECG diagnosis: New ST-elevation (≥1 mm) in ≥2 contiguous leads or a new LBBB.

Immediate reperfusion is critical: PCI within 90 minutes is the gold standard over thrombolysis.

Use thrombolysis (tPA) only if PCI is unavailable within 120 minutes of first medical contact.

For right ventricular (RV) infarcts, avoid nitrates/morphine and give IV fluids to maintain preload.

Aspirin (162-325 mg) should be administered immediately to all patients with suspected ACS.

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