# Restrictive Cardiomyopathy

Restrictive cardiomyopathy requires rapid separation from constrictive pericarditis and etiologic classification because amyloidosis, sarcoidosis, iron overload, storage disorders, and endomyocardial disease have divergent confirmatory tests, disease-directed treatments, arrhythmia risks, and transplant implications.

**Clinical question:** How should clinicians confirm restrictive cardiomyopathy, distinguish constriction, identify its cause, and direct treatment?

Updated: 2026-09-15T22:56:27.850081+00:00

## What matters in practice
- Restrictive cardiomyopathy is a phenotype of persistent restrictive physiology, nondilated ventricles, and atrial enlargement; wall thickness and ejection fraction may be normal or abnormal. [19][20]
- Exclude hypertensive heart disease, hypertrophic cardiomyopathy, and constrictive pericarditis before assigning primary restrictive cardiomyopathy. [1]
- CMR with T1, T2, and extracellular-volume mapping can refine etiologic classification and reduce—but not eliminate—the need for endomyocardial biopsy. [1]
- Endomyocardial biopsy is reasonable in restrictive disease when tissue will establish a treatable diagnosis, including amyloidosis, sarcoidosis, hemochromatosis, or storage disease. [1][9]
- Use diuretics for congestion while pursuing cause-directed therapy; mechanical circulatory support is difficult with a small LV, so selected patients require early transplant consideration. [5][23]

## Confirm restrictive physiology before labeling restrictive cardiomyopathy

The phenotype is hemodynamic; the etiologic diagnosis determines treatment.

Restrictive cardiomyopathy (RCM) requires persistent restrictive LV physiology with diastolic dysfunction, nondilated ventricles, and atrial enlargement. Ventricular wall thickness and systolic function do not define the phenotype: infiltration, intracellular storage, or cardiomyocyte hypertrophy can all increase wall thickness, and restrictive physiology may emerge early or late in a disease course. [19][20]

Start with 12-lead ECG and transthoracic echocardiography with Doppler assessment of filling physiology, chamber size, wall thickness, systolic function, and valve disease. Doppler echocardiography or cardiac catheterization can demonstrate restrictive pathophysiology; use the full clinical-imaging pattern rather than ventricular wall thickness alone. [19]

Before diagnosing RCM, actively evaluate competing phenotypes. Hypertensive heart disease and hypertrophic cardiomyopathy must be excluded, and constrictive pericarditis remains a critical alternative because it can mimic restrictive filling but has a fundamentally different procedural treatment pathway. [1][12]
- Treat a restrictive pattern as a phenotype rather than a final diagnosis; sarcoidosis and iron-overload cardiomyopathy may evolve toward a hypokinetic, dilated phenotype. [20]
- Consider an HCM overlap phenotype when unexplained hypertrophy is present: adult HCM imaging criteria include maximum end-diastolic wall thickness at least 15 mm without another cause, or at least 13 mm with family history or a positive genetic test. [21]
- Obtain invasive hemodynamics when noninvasive data do not resolve restriction versus constriction and the distinction will change management. [19][1]

*Phenotypic features that should trigger etiologic evaluation for RCM. [19][20]*

| Finding | Interpretation | Next decision |
| --- | --- | --- |
| Persistent restrictive physiology with nondilated ventricles and atrial enlargement | Supports the RCM phenotype regardless of wall thickness or ejection fraction. [19] | Proceed to etiologic classification with clinical history, ECG, echocardiography, CMR, nuclear imaging when appropriate, and targeted laboratory or genetic assessment. [19] |
| Increased ventricular wall thickness | May reflect hypertrophy, extracellular infiltration such as amyloidosis, or intracellular storage including glycogenosis, hemochromatosis, and sphingolipidoses. [20] | Do not assume HCM; identify the myocardial substrate. [20][21] |
| Restrictive physiology with unresolved pericardial versus myocardial mechanism | Constrictive pericarditis can resemble RCM on clinical evaluation. [1][12] | Use advanced imaging and, when required, catheterization or biopsy to establish the mechanism. [1][19] |

## Use imaging and targeted testing to identify the actionable cause

Etiologic classification should follow the dominant myocardial pattern and extracardiac clues.

Organize the differential into four mechanistic branches: interstitial fibrosis or intrinsic myocardial dysfunction, extracellular infiltration, intracellular storage, and endomyocardial fibrosis. The common secondary causes include amyloidosis, sarcoidosis, primary or secondary hemochromatosis, Fabry disease and other storage disorders, metastatic cancer, and radiation-induced disease; idiopathic RCM and endomyocardial fibrosis are primary forms. [1][19]

Use cardiovascular magnetic resonance (CMR), including T1, T2, and extracellular-volume mapping, when echocardiography establishes a restrictive phenotype but does not identify the substrate. CMR can reduce the diagnostic need for biopsy and provides tissue characterization relevant to amyloidosis, iron overload, sarcoidosis, and endomyocardial disorders. [1][12]

History should drive targeted evaluation: previous chest radiation or metastatic malignancy raises radiation-related or malignant myocardial disease; systemic sarcoidosis raises cardiac sarcoidosis; iron-overload states raise hemochromatosis; neuropathy or other familial systemic manifestations raise transthyretin amyloidosis or storage disease. Cardiac amyloidosis is the most common RCM cause in developed countries, particularly among older patients with heart failure and preserved ejection fraction. [1][18]

Perform genetic evaluation when familial RCM or an inherited phenocopy is suspected. Familial RCM is usually autosomal dominant and has meaningful phenotype-genotype overlap with HCM; associated genetic conditions include desminopathies, hereditary hemochromatosis, and Danon disease. [23]
- Suspect AL or transthyretin amyloidosis when an infiltrative phenotype is present; subtype confirmation matters because AL disease requires plasma-cell-directed therapy whereas TTR disease has TTR-directed treatment. [23]
- Evaluate sarcoidosis as an inflammatory and arrhythmogenic cause; CMR may reduce the need for cardiac biopsy, but tissue confirmation can be necessary when it will direct targeted treatment. [1]
- Consider endomyocardial fibrosis or Löffler-spectrum disease when an endomyocardial process is suggested by imaging; endomyocardial fibrosis is a distinctive RCM form and is more often reported in resource-limited settings. [4][12]
- Use a multidisciplinary cardiomyopathy or disease-specific referral pathway when interpretation of advanced imaging, genetics, biopsy, or disease-directed therapy is required. Complex cardiomyopathy decision-making may warrant consultation at an experienced HCM center when phenotypic overlap is substantial. [3]

### When to obtain tissue

Endomyocardial biopsy has a larger diagnostic role in RCM than in dilated or hypertrophic cardiomyopathy and carries an AHA/ACC Class IIa role in the diagnostic evaluation of restrictive disease. Right-ventricular biopsy can definitively establish cardiac involvement in systemic amyloidosis or hemochromatosis, and biopsy may occasionally help differentiate RCM from constrictive pericarditis. [1]

Reserve biopsy for cases in which tissue will resolve an uncertain diagnosis or identify a condition with targeted treatment, including amyloidosis, sarcoidosis, hemochromatosis, or metabolic storage disease. A normal biopsy does not exclude restrictive disease. [1][9]
- When sarcoidosis is systemic, biopsy of lymph node or lung tissue is safer and more sensitive than endomyocardial biopsy; a positive extracardiac biopsy plus compatible cardiac imaging and clinical findings can establish cardiac sarcoidosis. [11]
- Use CMR findings to target the decision for biopsy rather than performing biopsy solely because restrictive physiology is present. [1]

*Actionable etiologic branches in restrictive cardiomyopathy. [1][18][19][23]*

| Etiologic branch | Clinical or imaging discriminator | Confirmatory direction and treatment consequence |
| --- | --- | --- |
| Amyloidosis | Common developed-world cause of RCM; consider in older patients with HFpEF and restrictive physiology. [1][18] | Subtype the amyloid process because AL and TTR disease require different disease-directed strategies; biopsy may establish cardiac involvement when needed. [1][23] |
| Sarcoidosis | Systemic sarcoidosis or compatible inflammatory myocardial phenotype; conduction abnormalities and sudden death have been reported in infiltrative cardiomyopathies. [1][10] | Use clinical and imaging evidence; favor extracardiac tissue when available. Acute inflammatory disease is treated with corticosteroid-based immunosuppression plus HF and arrhythmia management. [11][23] |
| Iron overload | Primary or secondary hemochromatosis can produce a restrictive phenotype and may later become hypokinetic and dilated. [1][20] | CMR and, when needed, biopsy help establish myocardial involvement; iron-binding therapy may slow further myocardial iron deposition. [1][9] |
| Storage or inherited disease | Fabry disease, glycogen storage disease, mucopolysaccharidosis, Danon disease, and desminopathy are recognized RCM causes. [1][9][23] | Use clinical phenotype and genetic evaluation; define the specific disorder before disease-directed therapy. [19][23] |
| Endomyocardial fibrosis | Endomyocardial pathology with restrictive physiology; a distinctive primary RCM form. [1][4] | Use CMR and tissue evaluation when diagnosis remains uncertain or management requires pathology. [1][12] |

## Relieve congestion while protecting preload and identifying rhythm complications

Symptom control does not replace etiologic treatment.

Use diuretics as the mainstay of heart-failure treatment in RCM, while simultaneously treating the underlying cause when identified. The restrictive ventricle has limited filling reserve, so reassess symptoms, blood pressure, renal function, and congestion after diuretic adjustment rather than assuming that standard heart-failure escalation will be tolerated. [5]

Obtain ECG at presentation and use ambulatory rhythm monitoring when palpitations, presyncope, or lightheadedness suggest intermittent arrhythmia. Although the periodic monitoring schedule is specified for HCM, its principles are useful in an RCM/HCM overlap phenotype: initial and follow-up ECG, 24- to 48-hour ambulatory monitoring, and monitoring longer than 24 hours or event recording when symptoms require correlation. [2]

Treat arrhythmias as part of the underlying disease pathway. Sarcoidosis requires management of inflammation with corticosteroid-based immunosuppression as well as guideline-directed heart-failure and arrhythmia therapy; infiltrative cardiomyopathies are also associated with conduction-system abnormalities and sudden cardiac death. [23][10]
- Escalate to advanced-heart-failure assessment for refractory congestion, low-output limitation, or progressive restrictive physiology despite cause-directed management. [23]
- Do not use small LV size as reassurance against advanced disease: restrictive physiology with preserved ejection fraction can still justify transplant referral in HCM overlap disease. [2][3]
- Use disease-specific arrhythmia evaluation when cardiac sarcoidosis, amyloidosis, or HCM overlap is suspected because the substrate and sudden-death risk differ. [10][21][23]

*Management priorities by immediate clinical problem. [5][10][23]*

| Problem | Immediate action | Escalation trigger |
| --- | --- | --- |
| Volume overload | Use diuretics and reassess clinical response and tolerance. [5] | Persistent congestion or progressive functional limitation despite therapy should prompt advanced-heart-failure evaluation and etiologic reassessment. [23] |
| Palpitations, presyncope, or lightheadedness | Obtain ECG and extended ambulatory monitoring or event recording for symptom-rhythm correlation. [2] | Documented arrhythmia or conduction disease should direct disease-specific arrhythmia management, particularly in sarcoidosis or infiltrative disease. [10][23] |
| Suspected active cardiac sarcoidosis | Initiate a corticosteroid-based immunosuppression strategy for acute inflammatory suppression while managing HF and arrhythmias. [23] | Use tissue, imaging, and clinical findings to confirm the diagnosis and monitor response. [11][23] |

## Match disease-directed treatment to amyloid subtype, inflammation, iron, or inherited disease

A tissue or molecular diagnosis can change prognosis and treatment.

For AL amyloidosis, disease-modifying treatment includes autologous stem-cell transplantation after bortezomib conditioning in eligible patients. For patients who are not transplant eligible, daratumumab, bortezomib, cyclophosphamide, and dexamethasone is a cited alternative regimen; coordinate treatment with an amyloidosis and hematology program because cardiac involvement materially affects treatment tolerance. [23]

For transthyretin amyloidosis, tafamidis reduces further TTR formation and prolongs survival. Patisiran and inotersen are approved for stage 1 or 2 familial TTR amyloidosis with polyneuropathy rather than specifically for cardiomyopathy in the cited guidance; patients receiving these agents require vitamin A supplementation, and inotersen- or patisiran-associated adverse effects cited include glomerulonephritis and thrombocytopenia. [23]

For iron-overload cardiomyopathy, pursue treatment directed at iron removal or binding because reducing ongoing iron deposition may slow myocardial injury. For cardiac sarcoidosis, pair corticosteroid-based inflammatory suppression with heart-failure and arrhythmia treatment rather than treating the restrictive physiology alone. [9][23]

For inherited and storage disorders, establish the specific genetic or metabolic diagnosis before considering targeted therapy. The RCM phenotype overlaps genetically with HCM and can arise from desminopathy, Danon disease, hereditary hemochromatosis, and other storage disorders; an etiologic label of idiopathic RCM should follow rather than precede this evaluation. [1][23]
- Do not extrapolate ATTR therapies to AL amyloidosis or vice versa; amyloid subtype determines the disease-modifying pathway. [23]
- Use biopsy when the distinction between amyloidosis, storage disease, iron overload, sarcoidosis, and nonspecific fibrosis will change therapy. [1][9]
- Reassess trajectory even in minimally symptomatic ATTR cardiomyopathy: over a median 3.7 years, approximately one third of asymptomatic patients developed heart-failure symptoms, while nearly as many died or required cardiac transplantation. [24]

*Cause-directed treatment decisions in RCM. [9][23][24]*

| Established cause | Disease-directed action | Monitoring or limitation |
| --- | --- | --- |
| AL amyloidosis | Consider autologous stem-cell transplantation after bortezomib conditioning when eligible; otherwise use daratumumab, bortezomib, cyclophosphamide, and dexamethasone. [23] | Coordinate cardiac and hematologic management because advanced cardiac involvement affects treatment selection and tolerance. [23] |
| TTR amyloidosis | Use tafamidis for TTR amyloidosis; it reduces further TTR formation and prolongs survival. [23] | Patisiran and inotersen are cited for stage 1 or 2 familial TTR polyneuropathy; provide vitamin A supplementation and monitor cited renal and hematologic adverse effects. [23] |
| Cardiac sarcoidosis | Use corticosteroid-based immunosuppression to suppress acute inflammation plus HF and arrhythmia therapy. [23] | Confirm using extracardiac tissue when available, integrated with cardiac clinical and imaging findings. [11] |
| Iron-overload cardiomyopathy | Use iron-binding treatment to reduce ongoing iron deposition and potentially slow myocardial damage. [9] | Recognize that phenotype may progress from restrictive physiology to hypokinetic dilation. [20] |

## Refer early for transplant evaluation when restrictive physiology becomes advanced

Preserved ejection fraction does not exclude end-stage restrictive disease.

Refer selected patients for transplant evaluation when advanced heart failure develops despite medical and cause-directed treatment. Mechanical circulatory support is often challenging in RCM because the LV is small; transplant may therefore become the principal advanced therapy option. [23]

In HCM with advanced heart failure, 20% to 50% have preserved ejection fraction with restrictive physiology, so transplant referral does not require reduced ejection fraction. Patients with HCM and advanced heart failure are also less likely to receive mechanical circulatory support because of small LV size and disease-specific anatomy. [2]

ATTR and AL amyloidosis do not automatically preclude transplant evaluation. Reported post-transplant outcomes are similar across ATTR, AL, and nonamyloid cardiomyopathy cohorts, although candidacy requires assessment of systemic disease burden and the ability to address the underlying process. [8]
- Do not delay referral until ejection fraction falls when the patient has persistent restrictive physiology, recurrent decompensation, or progressive functional limitation. [2][3]
- Use a transplant center to determine whether systemic amyloidosis, active inflammation, or a hereditary disorder changes candidacy or the timing of combined disease-directed therapy. [8][23]
- Continue etiologic workup during advanced-heart-failure referral because a targeted diagnosis may alter both pretransplant treatment and posttransplant planning. [1][23]

*Advanced-therapy considerations in restrictive phenotypes. [2][3][8][23]*

| Scenario | Key implication | Next step |
| --- | --- | --- |
| RCM with small LV and advanced heart failure | LV assist-device support is challenging. [23] | Initiate transplant-center evaluation rather than assuming durable mechanical support is feasible. [23] |
| HCM overlap with preserved EF and restrictive physiology | Advanced HF and transplant need can occur without reduced EF; 20% to 50% of advanced-HF HCM patients have this pattern. [2] | Refer according to advanced-HF criteria despite preserved EF. [2][3] |
| ATTR or AL amyloidosis under transplant consideration | Post-transplant outcomes have been reported as similar to nonamyloid cardiomyopathy cohorts. [8] | Assess extracardiac disease and coordinate amyloidosis-directed care with transplant planning. [8][23] |

## Common questions

### When should endomyocardial biopsy be pursued in restrictive cardiomyopathy?

Use endomyocardial biopsy when noninvasive testing cannot establish a diagnosis that would change therapy, particularly suspected amyloidosis, sarcoidosis, hemochromatosis, or metabolic storage disease. In systemic sarcoidosis, prefer accessible lymph node or lung biopsy when available because it is safer and more sensitive. [1][9][11]

## References
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.