++
For further information, see CMDT Part 10-44: Dilated Cardiomyopathy
+++
Essentials of Diagnosis
++
Symptoms and signs of heart failure
Echocardiogram confirms left ventricular (LV) dilation, thinning, and global dysfunction
Severity of right ventricular (RV) dysfunction critical in long-term prognosis
+++
General Considerations
++
Categorized as heart failure with reduced ejection fraction where the LV ejection fraction (EF) is defined as ≤ 40%
Characterized by reduced myocardial contractility in the absence of abnormal loading conditions such as with hypertension or valvular disease
Causes
Familial in up to 20–35% of cases
Idiopathic in a large proportion
Endocrine, inflammatory, and metabolic causes include
Nutritional diseases, such as deficiency of thiamine, selenium, and carnitine
May also be caused by prolonged tachycardia either from
Also associated with HIV, Chagas disease, rheumatologic disorders, iron overload, sleep apnea, amyloidosis, sarcoidosis, chronic alcohol usage, end-stage renal disease, or cobalt exposure ("Quebec beer-drinkers cardiomyopathy")
++
Prevalence averages 36 cases/100,000 in the United States and accounts for approximately 10,000 deaths annually
Blacks are afflicted three times as often as whites
++
Gradual development of heart failure symptoms in most patients
Rales
Elevated jugular venous pressure (JVP)
Cardiomegaly
S3 gallop rhythm
Murmurs of functional mitral or tricuspid regurgitation
Peripheral edema
Ascites
Cheyne-Stokes breathing, pulsus alternans, pallor, and cyanosis may be present in severe heart failure
++
Chest radiograph reveals
Cardiac MRI
Diagnostic study of choice for right ventricular dysplasia
Helpful in identifying inflammatory or infiltrative processes, such as sarcoidosis or hemochromatosis
MRI with gadolinium can also help define an ischemic etiology by noting gadolinium hyperenhancement consistent with myocardial scar from infarction or prior myocarditis
++