Stiff, non-compliant ventricles cause severe diastolic dysfunction with preserved EF; often from amyloid, hemochromatosis, sarcoid, or radiation.
Also known as: RCM, restrictive cardiomyopathy, cardiac amyloidosis, infiltrative cardiomyopathy
Overview
Cardiomyopathy characterized by markedly increased ventricular stiffness (impaired diastolic filling) with normal or near-normal systolic function and non-dilated ventricles. Atrial enlargement is prominent. Causes are commonly grouped as infiltrative (amyloidosis, sarcoidosis), storage (hemochromatosis, Fabry, glycogen storage), endomyocardial (endomyocardial fibrosis, Loeffler endocarditis), or noninfiltrative (idiopathic, scleroderma, radiation-induced).
Epidemiology
Less common than dilated or hypertrophic cardiomyopathy. Cardiac amyloidosis is the most common identifiable cause in older adults: transthyretin (wild-type ATTR-CM) is increasingly recognized in elderly males, while AL (light-chain) amyloidosis is associated with plasma cell dyscrasias and has worse prognosis. Hereditary ATTR is more prevalent in African American populations (Val122Ile variant).
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Radiation therapy to the chest (especially for lymphoma, breast cancer)
Scleroderma and other connective tissue diseases
Anthracycline chemotherapy
Endomyocardial fibrosis (tropical regions)
Pathophysiology
Infiltration, fibrosis, or storage of abnormal material increases myocardial stiffness, impairing ventricular relaxation and diastolic filling. Elevated filling pressures back up into atria (causing marked biatrial dilation and atrial arrhythmias) and into pulmonary and systemic venous beds. Systolic function (EF) is typically preserved until late in disease. The clinical picture is dominated by features of biventricular diastolic heart failure, often with right-sided predominance early.
Marked biatrial enlargement with normal-sized non-hypertrophied ventricles (except amyloid, which thickens walls); low ECG voltage with disproportionate echo wall thickness strongly suggests cardiac amyloidosis.
Differential diagnosis
Constrictive pericarditis — Pericardial thickening or calcification on CT/MRI, septal bounce, respirophasic septal shift on echo; equalization of diastolic pressures with discordant ventricular pressure-time tracings; KEY differential because constriction is surgically curable
HFpEF — Preserved EF with diastolic dysfunction but typically no infiltrative pattern, biopsy and MRI normal or nonspecific
Hypertrophic cardiomyopathy — Asymmetric septal hypertrophy, dynamic LVOT obstruction; preserved electrical voltage on ECG (low voltage paradoxically common in amyloid despite thick walls)
Pulmonary hypertension (primary) — Dominant RV failure with normal LV size and function on echo; right heart catheterization defines
Severe tricuspid regurgitation — Holosystolic murmur, prominent V wave, dilated RV; primary valve pathology on echo
Diagnostic workup
Labs
BNP / NT-proBNP (elevated, prognostic)
Troponin (often persistently elevated in cardiac amyloidosis)
BMP, LFTs
Serum and urine protein electrophoresis with immunofixation (SPEP/UPEP/SIFE), serum free light chains — to screen for AL amyloidosis
Iron studies and ferritin (hemochromatosis); HFE gene testing if iron overload
ACE level and calcium for sarcoidosis (low specificity)
CBC with differential (eosinophilia → Loeffler endocarditis)
Genetic testing for hereditary TTR variants in suspected hATTR
Imaging
Transthoracic echocardiography: biatrial enlargement, normal LV cavity size, increased wall thickness or 'granular sparkling' myocardium (amyloid), restrictive filling pattern (E/A >2, short deceleration time), preserved EF, apical sparing on speckle tracking ('cherry on top' pattern in amyloid)
Cardiac MRI: diffuse subendocardial or transmural late gadolinium enhancement (amyloid pattern), elevated native T1 and extracellular volume; can also detect sarcoid lesions, iron overload (T2*)
99mTc-pyrophosphate (PYP) scintigraphy: highly sensitive and specific for ATTR cardiac amyloidosis (grade 2-3 myocardial uptake in absence of monoclonal protein confirms diagnosis without biopsy)
CXR: clear lung fields with mild-to-moderate cardiomegaly (atrial enlargement)
Right heart catheterization: 'square root' or 'dip-and-plateau' diastolic pressure tracings; elevated and roughly equal RV and LV end-diastolic pressures; concordant respiratory variation (vs discordant in constriction)
Other studies
Endomyocardial biopsy for definitive tissue diagnosis when imaging and labs are inconclusive (e.g., AL amyloidosis confirmation, sarcoidosis)
Fat pad or abdominal wall biopsy with Congo red staining for amyloid
Differentiating restrictive cardiomyopathy from constrictive pericarditis — high-yield comparison.
Treatment
First-line
Treat the underlying cause whenever possible — the disease-modifying axis of restrictive cardiomyopathy
Cardiac AL amyloidosis: hematology referral for plasma cell-directed chemotherapy (e.g., daratumumab + cyclophosphamide + bortezomib + dexamethasone) and possible autologous stem cell transplant
Cardiac ATTR amyloidosis (wild-type or hereditary): TTR stabilizers (tafamidis) — proven to reduce mortality and hospitalization in ATTR-CM (ATTR-ACT trial); newer silencers (patisiran, inotersen, vutrisiran) for hereditary forms with polyneuropathy
Hemochromatosis: serial therapeutic phlebotomy or iron chelation (deferasirox, deferoxamine) for transfusion-dependent forms
Symptomatic HF management: gentle diuresis to relieve congestion while preserving preload (these patients are exquisitely preload-dependent)
Second-line / adjunct
Avoid agents that drop heart rate or preload excessively: nondihydropyridine calcium channel blockers and digoxin can be poorly tolerated and digoxin may bind amyloid fibrils, increasing toxicity
Beta-blockers tolerated poorly in amyloid (heart rate dependent for output) — use cautiously
Anticoagulation for AFib regardless of CHA2DS2-VASc score in cardiac amyloidosis (elevated thromboembolic risk even at low scores; atrial thrombi can occur in sinus rhythm)
Permanent pacemaker for advanced conduction disease
Heart transplantation (or combined heart-stem cell transplant for AL) in highly selected younger patients with localized disease
Complications
Progressive biventricular heart failure
Atrial fibrillation and flutter, with high thromboembolic risk
Heart block requiring permanent pacing (especially cardiac sarcoidosis and amyloidosis)
Sudden cardiac death (especially sarcoidosis with VT)
Congestive hepatopathy and cardiac cirrhosis
Extracardiac complications of the underlying disease (e.g., nephrotic syndrome in AL amyloid, autonomic neuropathy)
PANCE pearls
Differentiating restrictive cardiomyopathy from constrictive pericarditis is high-yield: pericardial thickening/calcification, respirophasic septal shift, and discordant LV/RV pressure tracings on RHC point to constriction (which is surgically curable).
Low ECG voltage with thickened LV walls on echo strongly suggests cardiac AMYLOIDOSIS — high-yield exam clue.
99mTc-PYP scintigraphy with grade 2 or 3 myocardial uptake AND no monoclonal protein detected by SPEP/UPEP/SIFE and serum free light chains diagnoses ATTR-CM without need for biopsy.
Tafamidis (TTR stabilizer) is the first disease-modifying therapy proven to reduce mortality in ATTR cardiomyopathy (ATTR-ACT trial).
Bilateral carpal tunnel syndrome, lumbar spinal stenosis, autonomic neuropathy, and macroglossia are extracardiac clues that may precede the cardiac diagnosis of amyloidosis by years.
References
AHA/ACC/HFSA 2022 — 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure (Heidenreich et al., JACC 2022)
ATTR-ACT Trial — Tafamidis Treatment for Patients with Transthyretin Amyloid Cardiomyopathy (Maurer et al., NEJM 2018)
AHA 2020 — Cardiac Amyloidosis: Evolving Diagnosis and Management (Kittleson et al., Circulation 2020)
ESC 2023 — 2023 ESC Guidelines for the Management of Cardiomyopathies (Arbelo et al., Eur Heart J 2023)
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