Updated: 2/21/2021

Cardiomyopathies

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Questions
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Snapshot
  • A 16-year-old boy presents to his pediatrician for syncope. In the past few months, he had syncopal episodes when he played football, soccer, and sprinting. His family history includes sudden cardiac death in several relatives. An echocardiogram shows marked hypertrophy and abnormal systolic anterior leaflet motion of the mitral valve. (Hypertrophic cardiomyopathy)
Introduction
  • Clinical definition
    • cardiomyopathies intrinsically affect the myocardium, leading to systolic or diastolic dysfunction
      • these do not include changes in the myocardium secondary to hypertension, coronary artery disease, or valvular disorders
    • types of cardiomyopathies
      • dilated cardiomyopathy (most common)
      • restrictive/infiltrative cardiomyopathy
      • hypertrophic cardiomyopathy (obstructive vs non-obstructive)
 
Cardiomyopathies

Dilated
Restrictive/Infiltrative
Hypertrophic 
Etiology
  • ABCD
    • Alcohol abuse
    • Beriberi (wet) 
    • Coxsackie B viral myocarditis
    • Chronic Cocaine use
    • Chagas disease
    • Doxorubicin toxicity
  • Hemochromatosis
  • Sarcoidosis
  • Titin mutation 
  • Peripartum cardiomyopathy
  • Radiation therapy
  • Loffler endocarditis (with endomyocardial fibrosis and eosinophilic infiltrate)
  • Endocardial fibroelastosis (in children)
  • Amyloidosis
  • Sarcoidosis 
  • Scleroderma
  • Troponin mutation
  • Hemochromatosis
  • Familial (most common)
    • autosomal dominant
    • mutations in sarcomere proteins (β-myosin heavy chain = myosin binding protein C > tropomyosin = troponin I/C - in order of frequency of mutations)
  • Idiopathic
Pathology
  • Systolic dysfunction from ↓ contractility and ↓ ejection fraction
  • Eccentric hypertrophy (sarcomeres added in series)
  • Stiff myocardium causes diastolic dysfunction
  • Preserved left ventricular systolic function
  • Diastolic dysfunction from compliance of left ventricle
  • Septal hypertrophy
  • Majority of cases are obstructive (hypertrophic obstructive cardiomyopathy)
  • Concentric hypertrophy (sarcomeres added in parallel)
Clinical presentation
  • Congestive heart failure
  • S3 sound
  • Systolic murmur
  • Progressive heart failure
  • Sudden cardiac death
  • S4 sound (and others can present with S3)
  • + Kussmaul sign
  • Syncope with activity
  • Sudden cardiac death (especially in young athletes)
  • S4 sound
  • Systolic murmur without radiation
    • ↑ with Valsalva and standing up
    • ↓ with hand grip and squatting
Diagnostic studies
  • Chest radiography
    • ballooning of heart
  • Echocardiogram
    • dilated ventricles and ↓ ejection fraction
  • Electrocardiogram
    • bundle branch block
  • Chest radiography
    • cardiomegaly and pulmonary congestion
  • Echocardiogram
    • thickening of all structures
    • diastolic dysfunction
  • Endomyocardial biopsy
    • the most accurate test for etiology
  • Electrocardiogram
    • may have low voltages
  • Echocardiography   
    • normal ejection fraction
    • hypertrophy
    • mitral regurgitation
    • decreased end systolic volume and end diastolic volume
  • Electrocardiogram
    • left ventricular hypertrophy
  • Histology
    • tangled and disoriented myofibrils
Treatment
  • Angiotensin-converting enzyme inhibitors
  • β-blockers
  • Spironolactone
  • Automatic implantable cardioverter/defibrillator
  • Biventricular pacemaker
  • Treat underlying condition
  • Diuretics
  • Heart transplant
  • Avoid athletic activities
  • β-blockers
  • Non-dihydropyridine calcium channel blockers
  • Implantable cardioverter/defibrillator

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Questions (11)
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(M1.CV.15.1) A 19-year-old basketball player unexpectedly collapses on the court. Several minutes later he returns to consciousness and is able to continue playing. This has happened several times before with similar outcomes. He had no significant past medical history. Which of the following is most likely to be found in this patient?

QID: 100517
1

Atheromatous plaque rupture

0%

(0/77)

2

Coagulation necrosis with loss of nuclei and striations

1%

(1/77)

3

Septal hypertrophy

84%

(65/77)

4

Postductal coarctation of the aorta

5%

(4/77)

5

Cardiac myxoma

8%

(6/77)

M 2 C

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(M1.CV.14.219) A 19-year-old Caucasian male collapsed from sudden cardiac arrest while playing in a college basketball game. Attempts at resuscitation were unsuccessful. Post-mortem pathologic and histologic examination found asymmetric left ventricular hypertrophy and myocardial disarray. Assuming this was an inherited condition, the relevant gene most likely affects which of the following structures?

QID: 100735
1

Cardiac cell sarcomere proteins

96%

(65/68)

2

Membrane potassium channel proteins

1%

(1/68)

3

Ryanodine receptors

0%

(0/68)

4

Autoimmune beta-cell antibodies

1%

(1/68)

5

Membrane sodium channels

1%

(1/68)

M 2 D

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(M1.CV.13.20) A 49-year-old man presents to his physician complaining of weakness and fatigue. On exam, he has significant peripheral edema. Transthoracic echocardiogram is performed and reveals a preserved ejection fraction with impaired diastolic relaxation. A representative still image is shown in Figure A. Which of the following is likely the cause of this patient's symptoms?

QID: 100536
FIGURES:
1

Previous treatment with doxorubicin

6%

(4/68)

2

Hemochromatosis

49%

(33/68)

3

Heavy, long-term alcohol consumption

18%

(12/68)

4

History of myocardial infarction

10%

(7/68)

5

History of a recent viral infection

16%

(11/68)

M 1 E

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(M1.CV.13.103) An 18-year-old African-American male presents to his family physician for a routine sports physical. He has a family history of sudden death at a young age. Upon physical examination the physician appreciates a systolic murmur. The intensity of the murmur increases when performing a valsalva maneuver. The physician refers the patient for an EKG, which is attached. What is the most likely cause of this murmur?

QID: 100619
FIGURES:
1

Aortic valve stenosis

6%

(5/80)

2

Mitral stenosis

1%

(1/80)

3

Tricuspid stenosis

2%

(2/80)

4

Hypertrophic cardiomyopathy

90%

(72/80)

5

Benign systolic flow murmur

0%

(0/80)

M 1 E

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(M1.CV.13.140) A 66-year-old female with a past medical history significant for hypertension and breast cancer that is in remission after chemotherapy, presents to her primary care physician complaining of progressive dyspnea, decreased exercise tolerance, and paroxysmal nocturnal dyspnea. On chest auscultation you note an S3. A chest radiograph and echocardiogram are shown in Figure A. Which of the following medications is likely responsible for the patient's current presentation?

QID: 100656
FIGURES:
1

Lisinopril

1%

(1/69)

2

Digoxin

4%

(3/69)

3

Cytarabine

4%

(3/69)

4

Hydrochlorothiazide

3%

(2/69)

5

Doxorubicin

87%

(60/69)

M 1 D

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(M1.CV.12.12) A 12-year-old girl with an autosomal dominant mutation in myosin-binding protein C is being evaluated by a pediatric cardiologist. The family history reveals that the patient's father died suddenly at age 33 while running a half-marathon. What was the likely finding on histological evaluation of her father's heart at autopsy?

QID: 100528
1

Myocyte disarray

88%

(68/77)

2

Amyloid deposits

5%

(4/77)

3

Eosinophilic infiltration

0%

(0/77)

4

Wavy myocytes

4%

(3/77)

5

Viral particles

0%

(0/77)

M 2 E

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Evidence (10)
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EXPERT COMMENTS (43)
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