> Table of Contents > Cardiomyopathy
Cardiomyopathy
Timothy P. Fitzgibbons, MD, PhD
Theo E. Meyer, MD, DPhil
image BASICS
DESCRIPTION
  • Cardiomyopathy encompasses a large group of diseases of the myocardium that commonly result in mechanical pump dysfunction. The current classification scheme attempts to differentiate between myocardial diseases confined to the myocardium (primary) and those due to systemic disorders (secondary). Specific causes of myocardial dysfunction due to other cardiovascular disorders are considered a third, separate category (1).
  • Classification of cardiomyopathy
    • Primary
      • Genetic
        • Hypertrophic cardiomyopathy (HCM)
        • Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D)
        • Left ventricular (LV) noncompaction (LVNC)
        • Glycogen storage (Danon type, PRKAG2)
        • Conduction defects
        • Mitochondrial myopathies
        • Ion channel disorders: long QT syndrome, Brugada, short QT syndrome, catecholaminergic ventricular tachycardia (CVPT), Asian SUNDS
      • Mixed
        • Dilated cardiomyopathy (DCM) (genetic or nongenetic)
        • Restrictive
      • Acquired
        • Myocarditis, stress cardiomyopathy, peripartum, tachycardia-induced, infants of type 1 diabetic mothers
    • Secondary (see list below)
      • Specific
        • Ischemic
        • Valvular
        • Hypertensive
        • Congenital heart disease
  • Patients with end-stage cardiomyopathy have stage D heart failure or severe symptoms at rest refractory to standard medical therapy.
  • System(s) affected: cardiovascular; renal
Pediatric Considerations
Etiology: idiopathic, viral, congenital heart disease, and familial
Pregnancy Considerations
May occur in women postpartum
EPIDEMIOLOGY
Predominant age: Ischemic cardiomyopathy is the most common etiology; predominantly in patients aged >50 years. Consider uncommon causes in young.
Incidence
  • 60,000 patients <65 years old die each year from end-stage heart disease.
  • 35,000 to 70,000 people might benefit from cardiac transplant or chronic support.
Prevalence
Most rapidly growing form of heart disease
ETIOLOGY AND PATHOPHYSIOLOGY
  • Ischemic heart disease: most common etiology; up to 66% of patients
  • Hypertension
  • Valvular heart disease
  • Primary genetic causes
  • Congenital heart disease
  • Peripartum/postpartum
  • Endocrine
    • Diabetes mellitus
    • Hyperthyroidism
    • Hypothyroidism
    • Hyperparathyroidism
    • Pheochromocytoma
    • Acromegaly
  • Nutritional deficiencies
    • Beriberi, pellagra, scurvy, selenium, carnitine, kwashiorkor
  • Autoimmune/collagen
    • Systemic lupus erythematosus
    • Dermatomyositis
    • Rheumatoid arthritis
    • Scleroderma
    • Polyarteritis nodosa
  • Infectious causes
    • Viral (e.g., HIV, coxsackievirus, adenovirus)
    • Bacterial and mycobacterial (e.g., diphtheria, rheumatic fever)
    • Parasitic (e.g., toxoplasmosis, Trypanosoma cruzi)
  • Infiltrative (2)
    • Amyloidosis
    • Gaucher disease
    • Hurler disease
    • Hunter disease
    • Fabry disease
  • Storage
    • Hemochromatosis
    • Fabry disease
    • Glycogen storage disease (type II, Pompe)
    • Niemann-Pick disease
  • Neuromuscular/neurologic
    • Duchenne and Emery-Dreifuss muscular dystrophies
    • Friedreich ataxia
    • Myotonic dystrophy
    • Neurofibromatosis
    • Tuberous sclerosis
  • Toxic
    • Alcohol
    • Drugs and chemotherapy: anthracyclines, cyclophosphamide, Herceptin
    • Radiation
    • Heavy metal, chemical agents
  • Inflammatory (granulomatous):
    • Sarcoidosis
  • Idiopathic
  • Endomyocardial
    • Endomyocardial fibrosis
    • Hypereosinophilic syndrome (Loeffler endocarditis)
Genetics
Autosomal dominant HCM is the most common form of primary genetic cardiomyopathy (1/500 in the general population). Genetic causes of DCM are less common, accounting for 1/3 cases, with mostly autosomal dominant inheritance. LNC and ARVC are also inherited in an autosomal dominant fashion in addition to LQTS and other ion-channel disorders.
RISK FACTORS
  • Hypertension
  • Hyperlipidemia
  • Obesity
  • Coronary artery disease
  • Diabetes mellitus
  • Smoking
  • Physical inactivity
  • Excessive alcohol intake
  • Dietary sodium
  • Obstructive sleep apnea
  • Chemotherapy
GENERAL PREVENTION
Reduce salt and water intake; home BP and daily weight measurement
image DIAGNOSIS
PHYSICAL EXAM
  • Tachypnea
  • Cheyne-Stokes breathing
  • Low pulse pressure
  • Cool extremities
  • Jugular venous distention
  • Bibasilar rales
  • Tachycardia
  • Displaced point of maximal impulse (PMI)
  • S3 gallop
  • Blowing systolic murmur
  • Hepatosplenomegaly
  • Ascites
  • Edema
DIFFERENTIAL DIAGNOSIS
  • Severe pulmonary disease
  • Primary pulmonary hypertension
  • Recurrent pulmonary embolism
  • Constrictive pericarditis
  • Some advanced forms of malignancy
  • Anemia
DIAGNOSTIC TESTS & INTERPRETATION
  • ECG: LV hypertrophy, interventricular conduction delay, atrial fibrillation, evidence of prior Q-wave infarction
  • Hyponatremia
  • Prerenal azotemia
  • Anemia
  • Mild elevation in troponin
  • Elevated B-type natriuretic peptide (BNP) or pro-BNP
  • Mild hyperbilirubinemia
  • Elevated liver function tests
  • Elevated uric acid
Initial Tests (lab, imaging)
  • ECG
  • Chest radiograph
    • Cardiomegaly
    • Increased vascular markings to the upper lobes
    • Pleural effusions may or may not be present.
  • P.161

  • Echocardiography
    • In DCM, 4-chamber enlargement and global hypokinesis are present.
    • In HCM, severe LV hypertrophy is present.
    • Segmental contraction abnormalities of the LV are indicative of previous localized myocardial infarction.
  • Cardiac MRI
    • May be useful to characterize certain nonischemic cardiomyopathies
  • Stress myocardial perfusion imaging (MPI)
    • Recommended in those with new-onset LV dysfunction or when ischemia is suspected.
Diagnostic Procedures/Other
Cardiac catheterization
  • Helpful to rule out ischemic heart disease
  • Characterize hemodynamic severity
  • Pulmonary artery catheters may be reasonable in patients with refractory heart failure to help guide management.
image TREATMENT
See “Heart Failure, Chronic” for detailed treatment protocols.
GENERAL MEASURES
  • Reduction of filling pressures
  • Treatment of electrolyte disturbances
MEDICATION
First Line
  • Systolic failure syndromes
    • ACE inhibitors: All considered equally effective; initiate at low doses and titrate as tolerated to target doses (3)[A].
    • ENTRESTO, a combination drug containing a neprilysin inhibitor and valsartan, was recently approved for the treatment of systolic HF (EF <40%) as an alternative to an ACE/ARB (4)[A].
    • Loop diuretics
      • May need to be given IV initially and then orally as patient stabilizes
    • Furosemide, 40 to 120 mg/day or TID (3)[A]
    • β-Blockers
      • Use with caution in acutely decompensated or low-cardiac output states.
      • Initiate with low doses and titrate as tolerated.
    • Metoprolol succinate, 12.5 to 200 mg/day; carvedilol, 3.125 to 25 mg BID; or bisoprolol, 1.25 to 10 mg/day (3)[A]
    • Patients with New York Heart Association (NYHA) II-IV heart failure, ejection fraction (EF) <35%, on standard therapy: aldosterone antagonists: spironolactone or eplerenone (3)[A]
    • Digoxin, 0.125 to 0.25 mg/day for symptomatic patients on standard therapy (3)[B]
    • Combination hydralazine/isosorbide dinitrate is first-line treatment in African American patients with class III-IV symptoms already on standard therapy and for all patients with reduced EF and symptoms incompletely responsive to ACE inhibitor and β-blocker (3)[A].
      • Contraindications
    • β-Blockers: low cardiac output, 2nd- or 3rd-degree heart block
    • Avoid use of diltiazem and verapamil in patients with systolic dysfunction.
    • Aldosterone antagonists: oliguria, anuria, renal dysfunction
    • Loop diuretics: hypokalemia, hypomagnesemia
    • ACE inhibitors: pregnancy, angioedema
  • Precautions
    • In patients with chronic kidney disease, digoxin dosage should be ≤0.125 mg/day and drug levels followed carefully to avoid toxicity.
    • Closely monitor electrolytes.
    • ACE inhibitors: Initiate with care if BP is low. Begin with low-dose captopril, such as 6.25 mg TID.
    • β-Blockers: Avoid in patients with evidence of poor tissue perfusion; they may further depress systolic function.
    • Milrinone, dobutamine: long-term use associated with increased mortality
  • Medications TO AVOID
    • NSAIDs
    • Glitazones
    • Cilostazol
Second Line
  • Angiotensin receptor blockers as an alternative to ACE inhibitors
  • Inotropic therapy (e.g., dobutamine or milrinone) for cardiogenic shock and support prior to surgery or cardiac transplantation (3)[B]
  • Continuous inotrope infusion may be considered in stage D outpatients for symptom control in those who are not eligible for transplantation or mechanical circulatory support (3)[B].
ISSUES FOR REFERRAL
Management by a heart failure team improves outcomes and facilitates early transplant referral.
ADDITIONAL THERAPIES
  • Prophylactic implantable cardioverter defibrillator (ICD) should be considered for patients with a left ventricular ejection fraction (LVEF) <35% and mild to moderate symptoms (3)[A].
  • Cardiac resynchronization therapy (CRT) is recommended and should be considered for patients in sinus rhythm with a QRS >150 ms, LVEF <35%, in functional class (FC) I-III and ambulatory FC IV patients (3)[A].
  • Patients with severe, refractory heart failure with no reasonable expectation of improvement should not be considered for an ICD.
  • Consideration of an LV assist device as “permanent” or destination therapy or cardiac transplantation is reasonable in selected stage D patients.
image ONGOING CARE
DIET
Low fat, low salt, fluid restriction
PROGNOSIS
˜20-40% of patients in NYHA FC IV die within 1 year. With a transplant, 1-year survival is as high as 94%.
REFERENCES
1. Maron BJ, Towbin JA, Thiene G, et al. Contemporary definitions and classification of the cardiomyopathies: an American Heart Association Scientific Statement from the Council on Clinical Cardiology, Heart Failure and Transplantation Committee; Quality of Care and Outcomes Research and Functional Genomics and Translational Biology Interdisciplinary Working Groups; and Council on Epidemiology and Prevention. Circulation. 2006;113(14):1807-1816.
2. Seward JB, Casaclang-Verzosa G. Infiltrative cardiovascular diseases: cardiomyopathies that look alike. J Am Coll Cardiol. 2010;55(27):1769-1779.
3. Yancy CW, Jessup M, Bozkurt B, et al. 2013 ACCF/AHA guideline for the management of heart failure: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;128(16):1810-1852.
4. McMurray JJ, Packer M, Desai AS, et al. Angiotensinneprilysin inhibition versus enalapril in heart failure. N Engl J Med. 2014; 371(11): 993-1004.
See Also
  • Alcohol Abuse and Dependence; Alcohol Withdrawal; Amyloidosis; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Hypertension, Essential; Hypothyroidism, Adult; Hypertrophic Cardiomyopathy; Protein-Energy Malnutrition; Rheumatic Fever; Sarcoidosis
  • Algorithm: Congestive Heart Failure: Differential Diagnosis
Codes
ICD10
  • I42.9 Cardiomyopathy, unspecified
  • I42.0 Dilated cardiomyopathy
  • I42.5 Other restrictive cardiomyopathy
Clinical Pearls
  • Cardiomyopathy represents the end-stage of a large number of disease processes involving the heart muscle.
  • Ischemic, hypertensive, postviral, familial, alcoholic, and incessant tachycardia-induced are the most common cardiomyopathy varieties seen in the United States.
  • Core therapy for heart failure applies salt restriction, diuretics, ACE inhibitors, β-blockers, digoxin, and electrical treatments, such as cardiac resynchronization and implantable defibrillators, as appropriate.