A 39-year-old female with poorly controlled systemic lupus erythematosus (SLE) presents to the emergency room with a cough and pleuritic chest pain. She states that she developed these symptoms 2 days prior. The pain appears to improve when the patient leans forward. She currently takes hydroxychloroquine for her systemic lupus erythematosus but has missed several doses recently. Her temperature is 99°F (37.2°C), blood pressure is 135/80 mmHg, pulse is 115/min, and respirations are 22/min. Physical examination reveals a rise in jugular venous pressure during inspiration. In addition to tachycardia, which of the following EKG patterns is most likely to be seen in this patient?

PR depressions and diffuse ST elevations

Peaked T waves with flattened P waves

Irregularly irregular QRS complexes with no P waves

ST segment depressions in leads II, III, and aVF

Prolonged PR interval with normal QRS complexes

A 36-year-old woman presents to the emergency department with chest discomfort and fatigue. She reports that her symptoms began approximately 1 week ago and are associated with shortness of breath, swelling of her legs, and worsening weakness. She’s been having transitory fevers for about 1 month and denies having similar symptoms in the past. Medical history is significant for systemic lupus erythematosus (SLE) treated with hydroxychloroquine. She had a SLE flare approximately 2 weeks prior to presentation, requiring a short course of prednisone. Physical exam was significant for a pericardial friction rub. An electrocardiogram showed widespread ST-segment elevation and PR depression. After extensive work-up, she was admitted for further evaluation, treatment, and observation. Approximately 2 days after admission she became unresponsive. Her temperature is 100°F (37.8°C), blood pressure is 75/52 mmHg, pulse is 120/min, and respirations are 22/min. Heart sounds are muffled. Which of the following is a clinical finding that will most likely be found in this patient?

Decreased systolic blood pressure by 8 mmHg with inspiration

Unequal blood pressure measurements between both arms

A 19-year-old woman is brought to the emergency department by ambulance 30 minutes after her neighbor found her unconscious on a running trail. Her neighbor reports that she has been training for a marathon since the beginning of the summer. She is alert and oriented but becomes irritable when realizing that she is at a hospital and refuses to answer questions. She appears tired. She is 174 cm (5 ft 7 in) tall and weighs 51 kg (112 lb). Her temperature is 35.5°C (96°F), pulse is 44/min, respirations are 20/min, and blood pressure is 84/48 mm Hg. Examination shows dry, scaly skin and dry mucous membranes. Cardiopulmonary examination shows a high-frequency, mid-to-late systolic murmur that is heard best at the apex. Her hemoglobin concentration is 11.9 g/dL. Which of the following is the most likely diagnosis?

Hypertrophic obstructive cardiomyopathy

A 68-year-old man comes to the physician because of fatigue and muscle cramps for the past 4 weeks. He has also noticed several episodes of tingling in both hands. He has not had fever or nausea. He has had a chronic cough for 10 years. He has chronic bronchitis, hypertension, and osteoarthritis of both knees. His father died from lung cancer. Current medications include salbutamol, ibuprofen, and ramipril. He has smoked 1 pack of cigarettes daily for 45 years. He is 175 cm (5 ft 9 in) tall and weighs 68 kg (163 lb); BMI is 22 kg/m2. His temperature is 36.7°C (98°F), pulse is 60/min, and blood pressure is 115/76 mm Hg. While measuring the patient's blood pressure, the physician observes carpopedal spasm. Cardiopulmonary examination shows no abnormalities. His hematocrit is 41%, leukocyte count is 5,800/mm3, and platelet count is 195,000/mm3. Serum alkaline phosphatase activity is 55 U/L. An ECG shows sinus rhythm with a prolonged QT interval. Which of the following is the most likely underlying cause of this patient's symptoms?

Destruction of parathyroid glands

A 23-year-old Sicilian male presents to his primary care physician complaining of lethargy, joint pain, and urinary frequency. Vitals signs include T 98.7 F, HR 96 bpm, BP 135/71 mm/Hg, RR 18 breaths/minute, O2 99%. Laboratory findings include: random glucose 326 mg/dL, Hemoglobin 7.1, and elevated reticulocyte count and transferrin saturation. The patient is not surprised that his "blood level is low" and suggests that he might need another transfusion. An echocardiogram demonstrates restrictive cardiomyopathy. The disorder with which this patient presents can be characterized by which of the following?

Absence of the hemoglobin beta-chain

Mutations resulting in copper accumulation

Presence of the fetal hemoglobin

Absence of the hemoglobin alpha-chain

Mutation resulting in increased iron absorption

A 43-year-old woman presents to the emergency department complaining of palpitations, dry cough, and shortness of breath for 1 week. She immigrated to the United States from Korea at the age of 20. She says that her heart is racing and she has never felt these symptoms before. Her cough is dry and is associated with shortness of breath that occurs with minimal exertion. Her past medical history is otherwise unremarkable. She has no allergies and is not currently taking any medications. She is a nonsmoker and an occasional drinker. She denies illicit drug use. Her blood pressure is 100/65 mm Hg, pulse is 76/min, respiratory rate is 23/min, and temperature is 36.8°C (98.2°F). Her physical examination is significant for bibasilar lung crackles and a non-radiating, low-pitched, mid-diastolic rumbling murmur best heard at the apical region. In addition, she has jugular vein distention and bilateral pitting edema in her lower extremities. Which of the following best describes the infectious agent that led to this patient’s condition?

A bacterium that induces complete lysis of the red cells of a blood agar plate with an oxygen-sensitive cytotoxin

A bacterium that induces partial lysis of red cells with hydrogen peroxide

A bacterium that requires an anaerobic environment to grow properly

A bacterium that does not lyse red cells

A bacterium that induces heme degradation of the red cells of a blood agar plate

Cardiac manifestations of systemic diseases for USMLE Step 2 CK: High-Yield Internal Medicine Lessons

Endocrine & Metabolic - Hormonal Heart Havoc

Diabetes Mellitus: Diabetic cardiomyopathy (diastolic → systolic dysfunction), accelerated atherosclerosis (CAD), and autonomic neuropathy causing silent MIs.
Hyperthyroidism: High-output heart failure, sinus tachycardia, palpitations, and increased contractility. Prone to atrial fibrillation.
Hypothyroidism: Bradycardia, pericardial effusions (low voltage ECG, electrical alternans), diastolic hypertension, and severe hyperlipidemia.
Acromegaly: Concentric myocardial hypertrophy, diastolic dysfunction, hypertension.
Pheochromocytoma: Paroxysmal hypertension, tachyarrhythmias, and catecholamine-induced cardiomyopathy.

Echocardiogram: Concentric LVH in Acromegaly

⭐ Atrial fibrillation is the most common arrhythmia in hyperthyroidism, seen in 10-20% of patients; always screen for thyroid dysfunction in new-onset AF.

Rheumatologic Disease - Autoimmune Heart-ache

Libman-Sacks endocarditis: mitral valve vegetations

Systemic Lupus Erythematosus (SLE):
- Most common: Fibrinous pericarditis.
- Classic: Libman-Sacks Endocarditis (LSE) - small, sterile vegetations on mitral/aortic valves.
Ankylosing Spondylitis:
- Aortitis of the aortic root → Aortic regurgitation, conduction defects.
Rheumatoid Arthritis (RA):
- Pericarditis, rheumatoid nodules in myocardium & valves.
Scleroderma (Systemic Sclerosis):
- Myocardial fibrosis, vasospasm, pulmonary hypertension → cor pulmonale.

⭐ Libman-Sacks endocarditis vegetations are non-bacterial, verrucous, and characteristically found on both sides of the valve leaflets.

Infiltrative Disease - Crowded House Heart

Pathophysiology: Myocardial infiltration by abnormal substances → stiff, non-compliant ventricles → Restrictive Cardiomyopathy (RCM) with diastolic dysfunction.
Amyloidosis
- Extracellular protein fibril deposition.
- ECG: Low voltage QRS complexes, pseudo-infarct pattern.
- Echo: ↑ ventricular wall thickness, "sparkling" or speckled myocardium.
- Dx: Endomyocardial biopsy with Congo red stain (apple-green birefringence).
Sarcoidosis
- Non-caseating granuloma infiltration.
- High risk of AV block, ventricular arrhythmias, and sudden cardiac death.
- Dx: Cardiac MRI is key; biopsy is gold standard but often false-negative.
Hemochromatosis
- Iron overload (hereditary or secondary).
- Can present as dilated or restrictive cardiomyopathy.
- Dx: ↑ ferritin, ↑ transferrin saturation.

⭐ Classic board question: Suspect cardiac amyloidosis with the triad of heart failure, low-voltage ECG, and increased ventricular wall thickness on echocardiogram.

Cardiac amyloidosis with apple-green birefringence

High‑Yield Points - ⚡ Biggest Takeaways

Systemic Lupus Erythematosus (SLE): Pericarditis is the most common manifestation. Classic finding is Libman-Sacks endocarditis (sterile vegetations on both valve surfaces).

Ankylosing Spondylitis: Associated with aortitis of the aortic root, which can lead to aortic regurgitation.

Scleroderma: Often causes pulmonary hypertension, leading to cor pulmonale and right heart failure.

Sarcoidosis: Granulomatous infiltration of the myocardium can cause AV block, arrhythmias, and cardiomyopathy.

Amyloidosis: Causes restrictive cardiomyopathy with a classic low-voltage ECG despite ventricular hypertrophy.

Hemochromatosis: Iron deposition leads to dilated cardiomyopathy and conduction abnormalities.

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