A 43-year-old woman presents to her primary care provider with shortness of breath. She reports a 4-month history of progressively worsening difficulty breathing with associated occasional chest pain. She is a long-distance runner but has had trouble running recently due to her breathing difficulties. Her past medical history is notable for well-controlled hypertension for which she takes hydrochlorothiazide. She had a tibial osteosarcoma lesion with pulmonary metastases as a child and successfully underwent chemotherapy and surgical resection. She has a 10 pack-year smoking history but quit 15 years ago. She drinks a glass of wine 3 times per week. Her temperature is 98.6°F (37°C), blood pressure is 140/85 mmHg, pulse is 82/min, and respirations are 18/min. On exam, she has increased work of breathing with a normal S1 and loud P2. An echocardiogram in this patient would most likely reveal which of the following?

Right ventricular hypertrophy with a dilated pulmonary artery

Biventricular dilatation with a decreased ejection fraction

Left ventricular dilatation with an incompetent aortic valve

Left atrial dilatation with mitral valve stenosis

Left ventricular hypertrophy with a bicuspid aortic valve

A 45-year-old African American woman presents to her family physician for a routine examination. Past medical history is positive for amyloidosis and non-rhythm-based cardiac abnormalities secondary to the amyloidosis. Which of the following cardiac parameters would be expected in this patient?

Preserved ejection fraction and decreased compliance

Increased ejection fraction and decreased compliance

Preserved ejection fraction and increased compliance

Increased ejection fraction and increased compliance

Decreased ejection fraction and normal compliance

A 14-year-old boy who has been otherwise healthy presents to his doctor complaining of feeling easily winded and light-headed at basketball practice. He has never felt this way before and is frustrated because he is good enough to make varsity this year. He denies smoking, alcohol, or recreational drug use. His mother is very worried because her oldest son and brother had both died suddenly while playing sports despite being otherwise healthy. The transthoracic echocardiogram confirms the suspected diagnosis, which demonstrates a preserved ejection fraction and systolic anterior motion of the mitral valve. The patient is advised that he will need to stay hydrated and avoid intense exercise, and he will likely need an ICD due to his family history. Which of the following physical exam findings is consistent with this patient’s most likely diagnosis?

Systolic ejection murmur that worsens with the Valsalva maneuver

Systolic ejection murmur that radiates to the carotids

A 54-year-old woman presents to the emergency ward with a chief complaint of chest pain. The pain is sharp and present in the anterior part of the chest. There is no radiation of the pain; however, the intensity is decreased while sitting and leaning forward. There is no associated shortness of breath. Vital signs are the following: blood pressure is 132/84 mm Hg; pulse rate is 82/min, rhythmic, and regular. Lungs are clear on auscultation and cardiovascular examination demonstrates scratchy and squeaking sounds at the left sternal border. Kussmaul sign is positive and ECG shows new widespread ST segment elevation and PR depression. The most likely cause for these findings in this patient is?

Right ventricular myocardial infarction

A 38-year-old woman comes to the physician because of frequent headaches and blurring of vision. She also complains of weight gain, menstrual irregularities, and excessive growth of body hair. She says that, for the first time since she turned 18, her shoe and ring sizes have increased, and also complains that her voice has become hoarser. She does not smoke or drink alcohol. She takes no medications. Vital signs are within normal limits. Physical examination shows prominent frontal bossing, a protuberant mandible with spaces between the teeth, and large hands and feet. Serum studies show: Na+ 140 mEq/L Cl− 102 mEq/L K+ 4.1 mEq/L Ca2+ 10.6 mg/dL Phosphorus 4.7 mg/dL Glucose 180 mg/dL Which of the following is the most likely sequela of this patient's condition?

Deposition of mucopolysaccharides in the myocardium

Thickening of the coronary artery walls

Prolongation of the QT interval on ECG

A 34-year-old woman, gravida 2, para 2, is admitted to the hospital because of shortness of breath and fatigue 2 weeks after delivery of a full-term female newborn. She has no history of major medical illness. Cardiac examination on admission shows an S3 gallop and a grade 2/6 holosystolic murmur heard best at the apex. Treatment is initiated with intravenous furosemide and captopril. Her symptoms resolve, and 3 weeks later, cardiac examination shows no murmur. Which of the following is the most likely explanation for the initial auscultation findings?

Myxomatous mitral valve degeneration

An 80-year-old African American male presents complaining of worsening shortness of breath that occurs during his weekly round of golf. He also notes he has been waking up at night "choking and gasping for air", though he has been able to gain some relief by propping his head on a stack of pillows before he goes to bed. Upon auscultation, a low frequency, early diastolic gallop is heard over the apex while the patient rests in the left lateral decubitus position. This finding is most consistent with which of the following?

Left ventricular eccentric hypertrophy

Left ventricular concentric hypertrophy

Cardiomyopathies for USMLE Step 3: High-Yield Internal Medicine Lessons

Cardiomyopathies - The Big Three

Overview: Diseases of the heart muscle leading to impaired cardiac function.

Feature	Dilated (DCM)	Hypertrophic (HCM)	Restrictive (RCM)
Systolic/Diastolic	Systolic Dysfunction	Diastolic Dysfunction	Diastolic Dysfunction
EF	↓↓ (< 40%)	Normal or ↑	Normal
Ventricle	Dilated, thin wall	Thickened wall	Rigid, non-dilated
Key Cause	Idiopathic, Alcohol	Genetic (AD)	Amyloidosis, Sarcoid
Heart Sounds	S3 Gallop	S4 Gallop	S3 Gallop

⭐ HCM Murmur: Murmur intensity decreases with maneuvers that ↑ preload/afterload (e.g., squatting, handgrip).

Cardiomyopathy Classification Table

Dilated Cardiomyopathy - Stretched & Weak

Pathophysiology: Impaired contractility (systolic dysfunction) → ↓ ejection fraction (<40%) → ventricular dilation. Most common cardiomyopathy.
Etiologies: Mostly idiopathic. 📌 ABCCCD
- Alcohol (reversible)
- Beriberi (wet), Bug (Chagas disease)
- Cocaine, Coxsackie B
- Chemotherapy (Doxorubicin)
- Dystrophy (muscular)
Clinical: S3 gallop, mitral/tricuspid regurgitation, balloon-like heart on CXR.
Diagnosis: Echo is key → shows LV dilation & ↓ EF.

⭐ Reversible Causes: Key reversible causes include alcohol toxicity, thyroid dysfunction, and tachycardia-induced cardiomyopathy. Always consider these in new-onset HF.

Interstitial Expansion and Pathological Hypertrophy in Heart

Hypertrophic Cardiomyopathy - Thick & Obstructed

Etiology: Autosomal dominant mutation in sarcomere protein genes (e.g., MYH7, MYBPC3).
Pathophysiology: Asymmetric left ventricular hypertrophy (LVH), particularly the septum, leading to dynamic LV outflow tract (LVOT) obstruction and severe diastolic dysfunction.
Clinical: Exertional dyspnea, angina, and syncope. Major cause of sudden cardiac death in young athletes.
Auscultation: Harsh crescendo-decrescendo systolic murmur at the left sternal border.

⭐ Exam Favorite: Maneuvers that decrease LV cavity size (↓ preload) like Valsalva or standing, worsen the obstruction and increase the murmur. Maneuvers that increase LV cavity size (↑ preload/afterload) like squatting or handgrip, decrease the murmur.

Dx: Echocardiogram shows septal wall thickness > 15 mm.
Rx: β-blockers, verapamil. Avoid preload-reducing agents (diuretics, nitrates).

Restrictive Cardiomyopathy - Stiff & Stubborn

Pathophysiology: Rigid, non-compliant ventricles lead to impaired diastolic filling and bi-atrial enlargement, with preserved systolic function initially.
Etiology: Primarily infiltrative diseases.
- Amyloidosis: Most common cause; associated with multiple myeloma, chronic inflammation.
- Sarcoidosis: Non-caseating granulomas infiltrate the myocardium.
- Hemochromatosis: Iron deposition.
Clinical: Resembles constrictive pericarditis. Predominantly right-sided HF symptoms (JVD, peripheral edema, ascites). Kussmaul's sign (paradoxical ↑JVP with inspiration) may be present.
Diagnosis:
- ECG: Low-voltage QRS complexes.
- Echocardiogram: Thickened ventricular walls, sparkling "granular" appearance in amyloidosis.

⭐ Exam Favorite: The combination of low voltage on ECG despite thickened myocardium on echo is a classic finding for cardiac amyloidosis.

Amyloid deposition in restrictive cardiomyopathy

High‑Yield Points - ⚡ Biggest Takeaways

Dilated cardiomyopathy, the most common form, presents with systolic dysfunction and is often idiopathic or due to alcohol abuse.

Hypertrophic cardiomyopathy is an autosomal dominant condition causing diastolic dysfunction; its murmur increases with Valsalva.

Restrictive cardiomyopathy results from infiltrative diseases like amyloidosis or sarcoidosis, leading to diastolic dysfunction.

Arrhythmogenic RV cardiomyopathy involves fibrofatty infiltration of the right ventricle, causing arrhythmias.

Takotsubo cardiomyopathy ("broken-heart syndrome") is a stress-induced, reversible apical ballooning.

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