Rosen & Barkin's 5-Minute Emergency Medicine Consult (132 page)

Use caution in geriatric dosing.

FOLLOW-UP

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

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

Patients with EF <35% may require referral for:

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

• Primary care
  
• Cardiology
  
• Genetic testing may be indicated.
  

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

• 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.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Cardiomyopathy, Hypertrophic
  
• Cardiomyopathy, Peripartum
  

CODES

• 425.4 Other primary cardiomyopathies
  
• 425.18 Other hypertrophic cardiomyopathy
  
• 674.54 Peripartum cardiomyopathy, postpartum condition or complication
  

BASICS

• Hypertrophic cardiomyopathy (HCM):
  
  • Genetic disorder affecting the sarcomere:
    
    • Various mutations
      
    • Many phenotypic variations
      
  • Hypertrophied (regionally or globally), nondilated left or, rarely, right ventricle in the absence of another cause of degree of hypertrophy observed, such as hypertension or aortic stenosis
    
  • 2 general types:
    
    • Nonobstructive (HCM)—75% of patients. Estimated around 1% annual mortality
      
    • Obstructive (HOCM)—25% of patients. More severe—estimated 2% annual mortality
      
  • Manifests at all ages, from neonate to elderly:
    
    • Most manifest in childhood and adolescence—pubertal growth spurt
      
    • Usually more severe when diagnosed at younger age
      
    • Small percent progress to reduced LV function
      
  • Clinical presentation in mid and late life not uncommon
    
    • May initially be misdiagnosed as asthma, COPD, deconditioning or sleep apnea
      
  • Lethal arrhythmias more common in younger patients
    
    • Most common cause of atraumatic death in young (<35 yo) athletes
      
  • Supraventricular arrhythmias common with incidence increasing with age
    
    • Atrial fibrillation both common and poorly tolerated
      
• Prevalence ∼1 in 500 adults general population:
  
  • Based on echocardiographic diagnosis
    
• Structural pathology:
  
  • Irregular, marked ventricular wall thickening with disarray of myofibrils in the thickened regions and fibrin deposition:
    
    • Affects higher-pressure LV more than right and, in obstructive form, if obstruction removed, hypertrophy decreases
      
    • Some phenotypes have progressive wall thinning with age—usually associated with thicker wall early
      
  • Thickening usually asymmetric involving the septum to a greater extent than the free ventricular wall
    
  • Atrial dilatation secondary to diastolic filling stiffness
    
  • Impaired microvascular dilation associated with intimal thickening and perivascular collagen deposition
    
• Outpatient long-term management
  
  • Avoidance of volume depletion and elevated cardiac demand—depending on degree and location of hypertrophy
    
  • Pharmacologic
    
    • β-Blockers or verapamil to slow and control rate, thus prolonging diastole
      
  • Implantable cardiac defibrillator
    
    • In patients with history of syncope, cardiac arrest, family member with sudden death, asymptomatic nonsustained ventricular tachycardia (VT), abnormal BP response to exercise, massive hypertrophy
      
  • Alcohol ablation of hypertrophic outflow-obstructing septal tissue
    
  • Surgical septal myectomy—improving statistics with more centers performing
    

• 1st cardiac disorder for which genetic basis identified (1989)
  
• Autosomal-dominant inheritance:
  
  • >10 associated genes found:
    
    • Most encode proteins for sarcomere
      
    • >700 distinct mutations recognized
      
  • High penetrance
    
  • Variable phenotypic expression
    
  • Some genotypes significantly more lethal:
    
    • Routine screening impractical at present
      
    • Increasing complexity with more understanding of interplay between primary sarcomere abnormalities and other genetic and nongenetic factors
      
    • Some mutations affect cell wall pumps—thus, association with dysrhythmias.
      

See “Genetics.”

DIAGNOSIS

• Obstructive symptoms correlate with exertion or suddenly assuming upright position—activities that decrease venous return or ventricular filling.
  
  • Severity depends on the location and degree of ventricular wall thickening.
    
• Shortness of breath
  
• Dyspnea on exertion
  
• Exertional or postprandial angina
  
• Presyncope
  
• Syncope
  
• CHF
  
• Cardiovascular collapse
  
• Dysrhythmias:
  
  • Paroxysmal atrial fibrillation:
    
    • Often leads to significant, rapid clinical deterioration when present with CHF
      
    • Elevated CVA risk from clots
      
  • Supraventricular tachycardia
    
  • Nonsustained VT
    
  • Bradydysrhythmia rare
    
  • VT or ventricular fibrillation may lead to sudden death.
    
• Prior therapy for known HCM might include surgery or alcohol injection to reduce septal bulk:
  
  • Potential for conduction blocks
    
  • Potential septal rupture
    
• Known cases with higher risk of arrhythmia may have implanted defibrillators.
  
• Family history of sudden death without apparent cause or known HCM
  

Due to potential increasing severity in adolescence, any young child with syncope without clear cause, or in association with exercise, should have more extensive, focused history for familial sudden death (standard is 3 generations) and possible referral for evaluation.

• No or subtle physical findings
  
• Most findings in patients with outflow tract obstruction, variably:
  
  • Loud, left-sided S4
    
  • Double apical cardiac impulse at the mid to upper sternum
    
  • Murmur:
    
    • Crescendo–decrescendo midsystolic murmur at the left sternal edge
      
    • Radiation to aortic and mitral areas, not to neck or axilla
      
    • Increasing in intensity with Valsalva maneuver or standing up
      
    • Quieter with recumbency, squatting, or handgrips
      
    • Frequent associated mitral regurgitation
      
  • With more severe obstruction, a more apparent murmur with radiation to the left sternal border
    
  • Radiation to the axilla if there is associated mitral insufficiency