Cardiomyopathy, Emergency Medicine

Basics

Description

Diseases of the myocardium associated with cardiac dysfunction:

Dilated:
- Idiopathic in 25% of all cases of heart failure
Hypertrophic
Restrictive
Arrhythmogenic right ventricular (RV)
Unclassified cardiomyopathy
Specific cardiomyopathy:
- Heart muscle disease associated with a systemic disease or condition

Genetic: 20-30%
Acquired
Idiopathic

Etiology

Dilated:
- Idiopathic
- Viral
- Genetic/toxic
- Immune
- Familial
Hypertrophic:
- Familial disease with autosomal dominance
Restrictive:
- Idiopathic
- Amyloid
Arrhythmogenic RV:
- Familial disease with dominant and recessive patterns
Specific infectious:
- Lyme disease
- Viral
- Chagas disease
- HIV
Toxic agents:
- Alcohol
- Chemotherapeutic agents
Peripartum
Metabolic:
- Hyperthyroidism
- Pheochromocytoma
- Takotsubo (stress catecholamine)
General system diseases:
- Lupus
- Scleroderma
- Neuromuscular diseases
- Amyloidosis

Idiopathic
Genetic:
- Inborn errors of metabolism
- Malformation syndromes
- Neuromuscular disease
- Familial isolated cardiomyopathy disorders
Acquired:
- Vitamin and/or trace mineral deficiencies
- Electrolyte disturbances
- Endocrine disorders
- Toxins
- Collagen vascular disease
- Immunologic disease
- Malignancy
- Morbid obesity
- Myocarditis
- Pulmonary disease
- Kawasaki disease
- Infection
- Radiation
- Congenital heart disease
- Asphyxia

Diagnosis

Signs and Symptoms

History

Antecedent illness or exposure:
- Chemotherapy
- HIV
- Lyme disease
- Viral
Underlying systemic condition:
- Hemochromatosis
- Sarcoidosis
- Pregnancy
Substance abuse history
Family history:
- Familial sudden death
Exertional complaints (syncope, dyspnea)
Dizziness
Near syncope and syncope
Palpitations
Sudden death
Ventricular arrhythmias
CHF

Irritability
Hepatomegaly
Generalized muscle weakness
Acute biochemical crisis
Hypoglycemia
Metabolic acidosis
Hyperammonemia
Cyanosis
Encephalopathy
Dysmorphic features

See Cardiomyopathy, Peripartum.
Physical Exam

Vital signs
Cardiopulmonary exam
Abdominal organomegaly
Edema
Other:
- Rash
- Goiter
- Systemic illness

Diagnosis Tests & Interpretation

Lab

CBC
Chemistry panel
Liver function tests, thyroid function tests
Cardiac biomarkers
Brain (B-type) natriuretic peptide: Level >100 pg/mL
Serologies: Not useful in the ED

Imaging

CXR:
- Dilated cardiomyopathy:
  - Cardiomegaly
  - Pulmonary congestion
  - Pleural effusions
- Hypertrophic cardiomyopathy (HCM):
  - See Cardiomyopathy, Hypertrophic.
- Restrictive cardiomyopathy:
  - Normal cardiac silhouette
  - Pulmonary congestion
Emergency transthoracic 2D echocardiography by emergency physician:
- Depressed LV ejection fraction (EF)
- Excludes pericardial tamponade
Formal echocardiography:
- Study of choice
- Identification of underlying disease
Nuclear scintigraphy:
- When ECG is indeterminate
- Determination of the thickness of the septum and free wall
- Alternatives to echocardiography
CT and MRI distinguish between constrictive pericarditis and restrictive cardiomyopathy.
MR comprehensive assessment of heart failure: Assess myocardial anatomy, regional and global function, and viability. Allows assessment of perfusion and acute tissue injury (edema and necrosis), and nonischemic heart failure, fibrosis, infiltration, and iron overload can be detected.

Diagnostic Procedures/Surgery
EKG:

HCM:
- Left ventricle (LV) hypertrophy
- Q-waves in leads II, III, aVF, V5, and V6 in the early teenage years (most specific)
Dilated, Lyme, Chagas, and toxic cardiomyopathies:
- Atrial fibrillation
- Heart block
- Conduction abnormalities
- Pseudoinfarct pattern with pathologic Q-waves in anterior and inferior leads without coronary artery disease

Takotsubo (stress cardiomyopathy) can mimic STEMI (ST-elevation MI).

Cardiac catheterization:
- Suspicion of ischemia
- Treatable systemic disease
HCM:
- Assessment of hemodynamic abnormalities
- Endomyocardial biopsy
- Evaluation for myocarditis or define etiology
Cardiac CT or MRI

Electrolytes
pH
Glucose
Ammonia level
Cardiac output
Dysmorphic evaluation
EKG
Echocardiogram:
- Genetic workup; see individual causes

Differential Diagnosis

Other causes of dyspnea:
- Chronic obstructive pulmonary disease
- Anemia
- Asthma
- Interstitial lung disease
- Pulmonary embolism
- Pericardial tamponade
- Valvular heart disease
- Ischemic heart disease
- Hypothyroidism
- Constrictive pericarditis, commonly confused with restrictive cardiomyopathy
Other causes of syncope:
- Hypovolemia
- Heat disorder
- Hypoglycemia
- Arrhythmia
- Cardiac ischemia

Treatment

Pre-Hospital

Monitor
Oxygen
Avoid or use a lower dose of nitroglycerin in suspected HCM
Decompensated heart failure:
- Nitroglycerin
- Noninvasive positive-pressure ventilation

Initial Stabilization/Therapy

Airway, breathing, and circulation:

Control airway as needed.
Supplemental oxygen
Noninvasive positive-pressure ventilation

Ed Treatment/Procedures

Anticoagulation:
- Dilated cardiomyopathy
- Standard treatment of atrial fibrillation
- Systemic embolization
Limited ED experience with agents effective in HCM:
- Disopyramide to reduce obstruction
- Amiodarone to convert and maintain sinus rhythm
Standard treatment of CHF
Standard treatment of dysrhythmias

Keep NPO until inborn errors of metabolism ruled out.
IV fluids:
- D10 should be given until defects in the protein or fatty acid metabolism pathways are ruled out.
- IV fluids need to be given slowly and judiciously to avoid rapid fluid shifts to the extravascular space.

Do not give any products with lactate to avoid worsening any metabolic acidosis or lactic acidemia:

Antioxidants and vitamin cofactors
L-Carnitine to increase mitochondrial energy metabolism
Standard treatment of CHF
Sodium dichloroacetate (DCA) acutely lowers acetic acid levels in patients with mitochondrial disorders.

Medication

Amiodarone: 5 mg/kg over 10 min
Carnitine: (Peds: 50-300 mg/kg/d PO or IV)
Digoxin: Start 0.125 mg IV
Diltiazem IV: 0.25 mg/kg actual body weight over 2 min (average adult dose: 20 mg); repeat bolus dose (may be administered after 15 min if the response is inadequate): 0.35 mg/kg actual body weight over 2 min (average adult dose: 25 mg); continuous infusion 10 mg/hr; rate may be increased in 5 mg/hr increments up to 15 mg/hr as needed
Disopyramide: 100-200 mg PO q6h
Esmolol IV: Loading dose: 500 Î¼g/kg over 1 min; follow with a 50 Î¼g/kg/min infusion for 4 min; infusion may be continued at 50 Î¼g/kg/min or, if the response is inadequate, titrated upward in 50 Î¼g/kg/min increments (increased no more frequently than q4min) to a max. of 200 Î¼g/kg/min
Furosemide: 20-40 mg IV to a max. of 200 mg on subsequent doses (peds: 1 mg/kg IV q12-24h)
Heparin: Load 80 IU/kg IV; then 18 IU/kg/hr
Metoprolol IV: 2.5-5 mg q2-5min (max. total dose: 15 mg over a 10-15-min period)
Milrinone: Bolus 50 Î¼g/kg IV over 10 min, then 0.375-0.75 Î¼g/kg/min IV
Nesiritide: Bolus 2 Î¼g/kg IV, then 0.01 Î¼g/kg/min IV with a max. of 0.03 Î¼g/kg/min
Nitroglycerin: 5 Î¼g/min IV titrate to SBP

Use caution in geriatric dosing.

Follow-Up

Disposition

Admission Criteria

New or suspected cardiomyopathy
Syncope in which dysrhythmias or HCM are possible etiologies
Familial history of premature sudden death
Cardiogenic shock

Discharge Criteria

Diagnosed cardiomyopathy with mild CHF that improves with ED therapy
Restrictive cardiomyopathy or HCM
Cardiology consultation for discharge planning

Issues for Referral
Patients with EF <35% may require referral for:

Single-chamber implantable cardioverter defibrillator
Atrial-synchronized biventricular pacing
Ventricular assist devices
Heart transplant

Follow-Up Recommendations

Primary care
Cardiology
Genetic testing may be indicated.

Pearls and Pitfalls

Emergency physician bedside echocardiography is a useful tool for patients with syncope or exertional symptoms
Obtaining family history in suspected cardiomyopathy

Additional Reading

ACC/AHA Guidelines for the diagnosis and treatment of hypertrophic cardiomyopathy. J Am Coll Cardiol. 2011;58(25):2703-2738.
Bybee KA, Prasad A. Stress-related cardiomyopathy syndromes. Circulation. 2008;118:397-409.
Egan DJ, Bisanzo MC, Hutson HR. Emergency department evaluation and management of peripartum cardiomyopathy. J Emerg Med. 2009;36(2):141-147.
Karamitsos TD, Francis JM, Myerson S, et al. The role of cardiovascular magnetic resonance imaging in heart failure. J Am Coll Cardiol. 2009;54:1407-1424.

Codes

ICD9

425.4 Other primary cardiomyopathies
425.18 Other hypertrophic cardiomyopathy
674.54 Peripartum cardiomyopathy, postpartum condition or complication
425.11 Hypertrophic obstructive cardiomyopathy
425.18 Other hypertrophic cardiomyopathy
425.9 Secondary cardiomyopathy, unspecified
425.5 Alcoholic cardiomyopathy
425.7 Nutritional and metabolic cardiomyopathy
425.8 Cardiomyopathy in other diseases classified elsewhere
429.83 Takotsubo syndrome

ICD10

I42.2 Other hypertrophic cardiomyopathy
I42.9 Cardiomyopathy, unspecified
O90.3 Peripartum cardiomyopathy
I42.0 Dilated cardiomyopathy
I42.1 Obstructive hypertrophic cardiomyopathy
I42.8 Other cardiomyopathies
I42.2 Other hypertrophic cardiomyopathy
I42.5 Other restrictive cardiomyopathy
I42.6 Alcoholic cardiomyopathy
I42.7 Cardiomyopathy due to drug and external agent
I51.81 Takotsubo syndrome

SNOMED

233873004 Hypertrophic cardiomyopathy (disorder)
62377009 Postpartum cardiomyopathy (disorder)
85898001 Cardiomyopathy (disorder)
399020009 Congestive cardiomyopathy (disorder)
233873004 Hypertrophic cardiomyopathy (disorder)
89461002 Primary cardiomyopathy
35728003 Familial cardiomyopathy (disorder)
415295002 Restrictive cardiomyopathy (disorder)
441541008 Takotsubo cardiomyopathy

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