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 60-year-old woman presents to the emergency room with chest pain that started 20 minutes ago while watching television at home. The pain is substernal and squeezing in nature. She rates the pain as 6/10 and admits to having similar pain in the past with exertion. Her past medical history is significant for diabetes mellitus that is controlled with metformin. The physical examination is unremarkable. An electrocardiogram (ECG) shows ST-segment depression in the lateral leads. She is started on aspirin, nitroglycerin, metoprolol, unfractionated heparin, and insulin. She is asked not to take metformin while at the hospital. Three sets of cardiac enzymes are negative. Lab results are given below: Serum glucose 88 mg/dL Sodium 142 mEq/L Potassium 3.9 mEq/L Chloride 101 mEq/L Serum creatinine 1.2 mg/dL Blood urea nitrogen 22 mg/dL Cholesterol, total 170 mg/dL HDL-cholesterol 40 mg/dL LDL-cholesterol 80 mg/dL Triglycerides 170 mg/dL Hematocrit 38% Hemoglobin 13 g/dL Leucocyte count 7,500/mm3 Platelet count 185,000 /mm3 Activated partial thromboplastin time (aPTT) 30 seconds Prothrombin time (PT) 12 seconds Urinalysis Glucose negative Ketones negative Leucocytes negative Nitrites negative Red blood cells (RBC) negative Casts negative An echocardiogram reveals left ventricular wall motion abnormalities. With the pain subsiding, she was admitted and the medications were continued. A coronary angiography is planned in 4 days. In addition to regular blood glucose testing, which of the following should be closely monitored in this patient?

Activated partial thromboplastin time (aPTT) alone

Prothrombin time and platelet count

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 69-year-old man is scheduled to undergo radical retropubic prostatectomy for prostate cancer in 2 weeks. He had a myocardial infarction at the age of 54 years. He has a history of GERD, unstable angina, hyperlipidemia, and severe osteoarthritis in the left hip. He is unable to climb up stairs or walk fast because of pain in his left hip. He had smoked one pack of cigarettes daily for 30 years but quit 25 years ago. He drinks one glass of wine daily. Current medications include aspirin, metoprolol, lisinopril, rosuvastatin, omeprazole, and ibuprofen as needed. His temperature is 36.4°C (97.5°F), pulse is 90/min, and blood pressure is 136/88 mm Hg. Physical examination shows no abnormalities. A 12-lead ECG shows Q waves and inverted T waves in leads II, III, and aVF. His B-type natriuretic protein is 84 pg/mL (N < 125). Which of the following is the most appropriate next step in management to assess this patient's perioperative cardiac risk?

Radionuclide myocardial perfusion imaging

24-hour ambulatory ECG monitoring

Two days after undergoing an uncomplicated total thyroidectomy, a 63-year-old woman has acute, progressive chest pain. The pain is sharp and burning. She feels nauseated and short of breath. The patient has a history of hypertension, type 1 diabetes mellitus, medullary thyroid cancer, multiple endocrine neoplasia type 2A, anxiety, coronary artery disease, and gastroesophageal reflux disease. She smoked half a pack of cigarettes daily for 24 years but quit 18 years ago. Current medications include lisinopril, insulin glargine, insulin aspart, sertraline, aspirin, ranitidine, and levothyroxine. She appears anxious and diaphoretic. Her temperature is 37.4°C (99.3°F), pulse is 64/min, respirations are 17/min, and blood pressure is 148/77 mm Hg. The lungs are clear to auscultation. Examination shows a 3-cm linear incision over the anterior neck with 1 mm of surrounding erythema and mild serous discharge. The chest wall and abdomen are nontender. There is 5/5 strength in all extremities and decreased sensation to soft touch on the feet bilaterally. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate next step in management?

Obtain an ECG and troponin T levels

Administer IV pantoprazole and schedule endoscopy

Discontinue levothyroxine and obtain fT4 levels

Administer IV levofloxacin and obtain chest radiograph

Obtain urine and plasma metanephrine levels

A 25-year-old man comes to the emergency department because of a 1-week-history of progressively worsening dyspnea and intermittent chest pain that increases on inspiration. He had an upper respiratory tract infection 2 weeks ago. His pulse is 115/min and blood pressure is 100/65 mm Hg. Examination shows inspiratory crackles bilaterally. His serum troponin I is 0.21 ng/mL (N < 0.1). An x-ray of the chest shows an enlarged cardiac silhouette and prominent vascular markings in both lung fields; costophrenic angles are blunted. A rhythm strip shows inverted T waves. Which of the following additional findings is most likely in this patient's condition?

Elevated brain natriuretic peptide

Opening snap with low-pitched diastolic rumble

Risk stratification in ACS for USMLE Step 1: High-Yield Internal Medicine Lessons

Risk Stratification - The Initial Triage

Initial triage uses risk scores to predict Major Adverse Cardiac Events (MACE) and guide therapy (invasive vs. conservative).
Key Scores:
- HEART Score: For ED chest pain; score ≤3 suggests low MACE risk, consider discharge.
- TIMI Score: For UA/NSTEMI; predicts 14-day mortality.
- GRACE Score: More complex; predicts in-hospital & 6-month mortality.

⭐ A HEART score of 0-3 is associated with a very low risk of MACE, making it a powerful tool for safely discharging patients from the Emergency Department.

HEART Score for Chest Pain Patients in the ED

ECG Findings - The First Fork

The initial 12-lead ECG is the critical branch point, separating patients into two management pathways: STEMI or NSTE-ACS.

STEMI Criteria:
- New ST-elevation (at J-point, ≥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.
NSTE-ACS Findings:
- ST-depression ≥0.5 mm.
- Deep T-wave inversions ≥1 mm.
- A normal ECG does not rule out ACS.

⭐ A posterior MI (LCA/RCA occlusion) may present with isolated ST depression in V1-V3. Obtain posterior leads (V7-V9) to unmask ST elevation.

Risk Scores - The Numbers Game

TIMI Score (Thrombolysis in Myocardial Infarction): Estimates 14-day risk of death, new/recurrent MI, or severe ischemia in UA/NSTEMI.
- 1 point for each of 7 variables:
  - Age ≥65 years
  - ≥3 CAD risk factors (HTN, HLD, DM, smoking, family Hx)
  - Known CAD (stenosis ≥50%)
  - Aspirin use in past 7 days
  - ≥2 anginal episodes in last 24 hrs
  - ST-segment deviation ≥0.5 mm
  - Elevated cardiac markers
- Risk: Low (0-2), Intermediate (3-4), High (≥5)
GRACE Score (Global Registry of Acute Coronary Events): Predicts in-hospital & 6-month mortality. More complex but more accurate than TIMI.
- Key Inputs: Age, Killip class, systolic BP, heart rate, creatinine, cardiac arrest, ST deviation, elevated enzymes.

⭐ The GRACE score (>140 = high risk) is superior to TIMI for risk stratification and is preferred by ACC/AHA guidelines to guide the timing of invasive strategy (e.g., angiography).

Biomarkers & Labs - The Molecular Clues

Cardiac Troponins (cTnI, cTnT): Gold standard for myocardial necrosis.
- High-sensitivity (hs-cTn) assays are standard.
- Rise: 2-4 hrs; Peak: 24-48 hrs; Lasts: 7-10 days.
- The change (delta) in serial levels is diagnostic.
CK-MB: Less specific than troponin.
- Primary use: detecting re-infarction due to faster normalization (48-72 hrs).
BNP/NT-proBNP: Indicates ventricular stretch; elevated levels correlate with HF risk and mortality.
Baseline Panel: CBC (anemia), BMP (K+, creatinine), Lipid profile.

Biomarkers in Acute Coronary Syndrome

⭐ While troponins are superior for initial diagnosis, CK-MB's rapid normalization makes it valuable for diagnosing re-infarction within days of the initial event.

High-Yield Points - ⚡ Biggest Takeaways

TIMI and GRACE scores are essential tools for ACS risk stratification to guide therapeutic intensity.

High-risk features mandating an aggressive approach include dynamic ST-T changes, elevated troponins, and hemodynamic instability.

Advanced age, diabetes, CKD, and known CAD are powerful predictors of adverse outcomes.

A high GRACE score (>140) or TIMI score (≥3) strongly favors an early invasive strategy.

Patients with low-risk scores may be managed conservatively.

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