Restrictive cardiomyopathy (RCM) is a rare type of cardiomyopathy characterized by marked diastolic dysfunction, normal (or near-normal) systolic function, and normal ventricular volumes. RCM occurs as a result of myocardium distortion due to proliferation of abnormal tissue or the deposition of abnormal compounds. Many diseases, both primary and acquired, cause RCM. Regardless of the etiology, RCM manifests with congestive heart failure (CHF), often with pronounced right-sided symptoms. Echocardiography is the first-line diagnostic test and is often followed by advanced imaging, including cardiac MRI. Initial management focuses on the followed by identification and treatment of the underlying cause. In severe or refractory cases, heart transplantation may be necessary.
RCM can be classified into four categories based on the underlying pathology; there is some overlap between the categories.
Infiltrative cardiomyopathy 
- Amyloidosis: caused by an accumulation of abnormal proteins in the myocardium
- Sarcoidosis: secondary to deposition of granulomas in the myocardium
- Primary hyperoxaluria: secondary to oxalate deposits in the myocardium
Storage disorders 
- Hereditary hemochromatosis; : increased absorption of iron from GI tract (more commonly causes dilated cardiomyopathy)
- Iron overload: increased systemic iron from repeated blood transfusions
- Congenital enzyme abnormalities
Endomyocardial disorders 
- Endomyocardial fibrosis: caused by autoantibodies against myocardial proteins
- Hypereosinophilia (Löffler endocarditis): eosinophilic infiltration of the myocardium 
- Endocardial fibroelastosis: a diffuse thickening of the left ventricle endocardium from the proliferation of fibrous and elastic tissue
- Malignancy: or metastatic tumor
Noninfiltrative restrictive cardiomyopathy
- Infiltration (e.g., abnormal proteins, glycogen, eosinophils, granulomas, iron) or proliferation of connective or fibrotic tissue → ↓ elasticity of myocardium → ↓ ventricular compliance (severe diastolic dysfunction) → ↓ ventricular filling in diastole → ↑ left and right-sided filling pressures → ↑ atrial size → ↑ pulmonary and systemic venous congestion → late-stage ↓ in LV systolic function → hypotension 
- Auscultatory findings
- Features of the underlying disease, e.g.: 
The symptoms and signs of heart failure are the most common clinical features of RCM. 
- Order initial studies (basic laboratory studies, ECG, x-ray chest, and echocardiogram) to confirm the diagnosis of RCM.
- Screen patients for associated complications.
- If the underlying etiology remains unclear, consider advanced studies (e.g., cardiac MRI or endomyocardial biopsy).
Initial studies 
- X-ray chest (PA and lateral)
- CBC with differential: Eosinophil count > 1.5 × 109/L is consistent with hypereosinophilic heart disease. 
- Comprehensive metabolic panel: Nephropathy and hepatopathy are common in amyloidosis.
- Troponin and NT-proBNP: to establish the extent of heart failure and establish a baseline for treatment monitoring 
Transthoracic echocardiography 
- TTE is the preferred initial test. 
- Characteristic findings of RCM 
- Severe diastolic dysfunction (high early diastolic filling velocities and low late diastolic filling velocities) 
- Normal right and left ventricular volumes
- Preserved ejection fraction (may be reduced in late-stage disease)
- Typically normal ventricular wall thickness (may be increased in amyloidosis, sarcoidosis, and lysosomal storage disease)
- Left atrial or biatrial enlargement
- Findings of underlying disease, e.g.:
Additional diagnostic studies
Assessment for associated disease states
- Ambulatory ECG monitoring (e.g., holter monitor): Indicated for patients with an abnormal ECG, symptomatic patients, and those with a history of sarcoidosis. 
Cardiac catheterization: used to assess for ischemic heart disease or constrictive pericarditis 
- Evaluation of secondary end-organ damage: Consider if found during initial studies, e.g., doppler ultrasound for cardiac cirrhosis, urine analysis and renal ultrasound in renal impairment
Screening studies for the suspected underlying cause
- Hemochromatosis: elevated ferritin and transferrin saturation 
- Amyloidosis: serum free light chains and serum and urine electrophoresis 
- Lysosomal storage diseases: enzyme and genetic testing 
Advanced studies for RCM
Cardiac MRI (CMR) 
- Can establish a definitive diagnosis
- Can help guide chronic management of RCM by quantitating myocardial disease
Endomyocardial biopsy (EMB) 
- EMB provides tissue for a definitive histological diagnosis (e.g., fibrosis, amyloidosis, iron deposition, granulomas, eosinophilic infiltrates in ).
- Guided biopsy with electroanatomic mapping or CMR or PET is recommended. 
- The use of EMB has decreased as cardiac MRI technology has improved. 
- Start symptomatic treatment of heart failure, including education on lifestyle modification.
- Screen for and treat associated diseases (e.g., arrhythmias, thromboembolism).
- Treat the underlying cause, when possible.
- Patients with severe or refractory symptoms:
- The initial management of RCM is the treatment of congestive heart failure symptoms.
- The unique physiology of RCM and its underlying disease processes may necessitate modifications to the standard treatment of CHF.
|Heart failure management in RCM |
|Medication||Treatment mechanism||Additional considerations specific to RCM|
|Beta blockers and calcium channel blockers (CCBs)|| |
|Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs)|| |
Management of associated arrhythmias 
- Treat atrial fibrillation.
- Consider the following, depending on ECG and Holter monitor findings:
- Anticoagulation is indicated for patients with a known thrombus, a high risk of thrombogenesis, or atrial fibrillation. 
- See “Anticoagulation in atrial fibrillation” for further information on anticoagulation, including dosages.
Definitive treatment depends on the specific etiology (see “Etiology” section).
|Disease-specific treatment of RCM ]#19367]|
|Infiltrative||Amyloidosis: lIght chain|
|Amyloidosis: transthyretin amyloidosis (ATTR)|
|Storage disorder||Hereditary hemochromatosis|
|Endomyocardial disorder||Hypereosinophilic syndrome|
|Noninfiltrative||Systemic sclerosis|| |
Management of severe or refractory RCM
- In patients who are unresponsive to medical therapy, consider mechanical circulatory support (e.g., LVAD), either as a destination therapy or a bridge to transplant. 
- Consider referral for a heart transplant (or heart and liver transplant in amyloidosis). 
- For patients who are not candidates for a heart transplant, refer to palliative care.
- RCM and constrictive pericarditis have similar clinical presentations. Distinguishing between the two diseases is critical to determining the appropriate management.
- See also “Cardiomyopathy” article.
|Restrictive cardiomyopathy versus constrictive pericarditis |
|X-ray chest|| || |
|Echocardiography|| || |
|CT or MRI chest|| || |
|Cardiac catheterization|| |
The differential diagnoses listed here are not exhaustive.
- The prognosis for RCM is generally poor. 
- Adult patients: The overall 5-year survival rate is approximately 50%.
- Pediatric patients: over 50% experience sudden cardiac death shortly after diagnosis