Cardiomyopathy

para>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 ⅓; 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 �

DIAGNOSIS

HISTORY

Dyspnea at rest or with exertion
Paroxysmal nocturnal dyspnea
Orthopnea
Postprandial dyspnea
Right upper quadrant pain or bloating
Midabdominal pain
Fatigue
Syncope
Edema

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.
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.

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.

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%. �

COMPLICATIONS

Worsening congestive heart failure syncope, renal failure, arrhythmias, or sudden death �

REFERENCES

11 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):1807-1816.22 Seward �JB, Casaclang-Verzosa �G. Infiltrative cardiovascular diseases: cardiomyopathies that look alike. J Am Coll Cardiol. 2010;55(27):1769-1779.33 Yancy �CW, Jessup �M, Bozkurt �B, et al. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;128(16):1810-1852.44 McMurray �JJ, Packer �M, Desai �AS, et al. Angiotensin-neprilysin inhibition versus enalapril in heart failure. N Engl J Med. 2014; 371(11): 993-1004.

CODES

ICD10

I42.9 Cardiomyopathy, unspecified
I42.0 Dilated cardiomyopathy
I42.5 Other restrictive cardiomyopathy
I42.8 Other cardiomyopathies
I42.7 Cardiomyopathy due to drug and external agent
I42.6 Alcoholic cardiomyopathy
I42.2 Other hypertrophic cardiomyopathy
I42.1 Obstructive hypertrophic cardiomyopathy

ICD9

425.4 Other primary cardiomyopathies
425.11 Hypertrophic obstructive cardiomyopathy
425.9 Secondary cardiomyopathy, unspecified
425.18 Other hypertrophic cardiomyopathy
425.5 Alcoholic cardiomyopathy
425.7 Nutritional and metabolic cardiomyopathy
425.8 Cardiomyopathy in other diseases classified elsewhere

SNOMED

85898001 Cardiomyopathy (disorder)
399020009 Congestive cardiomyopathy (disorder)
89461002 Primary cardiomyopathy
90828009 Primary restrictive cardiomyopathy (disorder)
415295002 Restrictive cardiomyopathy (disorder)
72972005 dilated cardiomyopathy secondary to drug (disorder)
83521008 Dilated cardiomyopathy secondary to alcohol (disorder)

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.

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