Restrictive Cardiomyopathy

Meet the patient

A 72-year-old man is back on the cardiology ward for the third time in a year with "HFpEF" that will not settle. He has bilateral carpal tunnel releases behind him, a ruptured biceps tendon he blames on the gym, and now a JVP that does not fall, an abdomen full of ascites, and an ECG whose voltages you can barely see.^[1][9]

He is the patient every cardiology firm admits as "diuretic-resistant right heart failure" — and he is the patient you must not send for pericardiectomy. Two questions are now live, and the whole topic exists to answer them: is this restriction or constriction? and what is stiffening his ventricle?^[1][6]

A stiff ventricle with a preserved pump — the first mark in the viva

This is a stiff-ventricle problem, not a pump problem. Systolic ejection is normal early; the ventricle simply cannot accept the blood returning to it. Filling pressures climb, the atria hypertrophy and balloon, and the patient drowns in venous congestion on a normal ejection fraction.^[5]

RCM is the least common of the three WHO cardiomyopathies — hypertrophic and dilated sit ahead of it. The label is the easy part; the skill is recognising that a stiff ventricle underlies the "HFpEF", naming the infiltrate, and separating it from constriction.^[5]

Why is systole spared at first? The contractile machinery is intact — amyloid, iron and granulomas sit in the interstitium, so myocyte shortening survives. Only late, once the load is heavy and replacement fibrosis sets in, does the pump fail — the "burnt-out" phase that predicts a poor outcome.^[1]

The AMISH list — what is stiffening this ventricle?

When the ventricle is stiff, name the cause before you name the drug. The aetiology decides everything that follows, and the AMISH mnemonic keeps the five families in one breath.^[1]

The two anatomical axes that earn a sub-mark. Split each cause by where the disease sits: myocardial RCM (amyloid, sarcoid, radiation, scleroderma, idiopathic) infiltrates the muscle itself; endomyocardial RCM (Löffler, tropical EMF, carcinoid) scars the lining under a coat of thrombus. The split predicts the imaging — apical obliteration is the endomyocardial fingerprint.^[1][7]

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Is this restriction or constriction? (The question that decides surgery)

This is the single most important decision in restrictive cardiomyopathy, because pericardiectomy cures constriction and is futile — even harmful — in RCM. The bedside signs overlap almost perfectly: raised JVP, Kussmaul, hepatomegaly, ascites. The discrimination happens on imaging and catheter, not at the bedside.^[6]

^[6]

The one-line discriminator to carry into the viva: BNP high plus no calcification points to restriction; BNP normal plus calcification points to constriction. Add a preserved septal e-prime (annulus paradoxus) and the case is closed.^[6]

The dip-and-plateau sign will not save you — it is shared

The square-root (dip-and-plateau) sign is the trap, because it appears in BOTH restriction and constriction and so does not discriminate. Early diastolic filling is rapid and then abruptly arrested in each — the ventricle fills fast, hits its limit, and the pressure plateaus. Seeing it confirms only that filling is restricted; it tells you nothing about the pericardium.^[6]

The three tests that actually separate the two are BNP, pericardial calcification and annulus paradoxus — not the square-root sign. Reach for those before you reach for the catheter tracings.^[6]

Kussmaul's sign is the other shared finding — use it for a different fork. A JVP that rises on inspiration is present in BOTH restriction and constriction, because the stiff right ventricle cannot accept the augmented venous return — but it is absent in tamponade. That makes it a three-way discriminator: restriction and constriction yes, tamponade no.^[6]

Voltage-mass discordance — amyloid until you exclude it

The classic trap: low voltages on the ECG with thick LV walls on the echo is amyloidosis until you have proven otherwise. Normally a thick wall means more muscle means bigger voltages; in amyloid the fibrils displace myocardium, so the wall is thick but the QRS is small. That discordance is the bedside signature of infiltration.^[1]

Add the apical sparing pattern on longitudinal strain — the "cherry on top", where basal and mid-wall strain fall away but the apex is preserved — and the picture is virtually diagnostic. On cardiac MRI the matched finding is diffuse subendocardial late gadolinium enhancement that will not null: the blood pool and myocardium null together because so much amyloid holds the gadolinium.^[1]

Etymology for viva gold: amyloid comes from the Greek amylon, "starch". Virchow named it because the deposits stained like starch with iodine. It is not starch — it is misfolded protein in beta-pleated sheets that takes up Congo red and glows apple-green under polarised light. The name is wrong; it stuck.^[3][4]

AL versus ATTR — read the amyloid type, because the treatment is opposite

Once amyloid is confirmed, the next question decides the drug: is it AL or ATTR? They share the stiff-ventricle phenotype but diverge completely in cause, pace and treatment. Light chains are directly toxic to myocytes, so AL is aggressive and chemo-responsive; transthyretin deposits more slowly, so ATTR runs for years and answers to a stabiliser.^[1][3]

^{[2] [3] [9] [13] [14] [16] [20] [21] [22]}

The one-line discriminator: light chains, macroglossia, periorbital purpura and a fast decline point to AL; carpal tunnel, biceps rupture, spinal stenosis in an elderly man point to ATTR.^[3][9]

Why the atria balloon and the patient drowns — the mechanism in three steps

Three structural problems converge on one haemodynamic phenotype. Whatever the infiltrate — amyloid fibrils, granulomas, iron, fibrous tissue — it displaces contractile myocardium and shifts the passive pressure-volume curve up and to the left, so a small gain in volume produces a large rise in pressure.^[1][4]

That produces restrictive early filling: the E-wave inflow is rapid and then stops dead as the stiff ventricle hits its limit, and atrial contraction adds almost nothing — the dip-and-plateau signature on catheter and the E-dominant, short-deceleration pattern on echo.^[1]

The atria pay the price. Pumping against a non-compliant ventricle they hypertrophy, dilate and finally fibrillate — the bi-atrial enlargement that is the radiological and echocardiographic hallmark, and the substrate for the atrial standstill and thrombus that complicate the disease.^[1]

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Who walks through the door — the red-flag patient

RCM is rare, but its causes cluster so tightly that the patient often hands you the diagnosis in the history. Ask about age, ancestry, occupation and region, past radiotherapy, chronic inflammation, and the orthopaedic and soft-tissue signs that precede ATTR by years.^[1]

• AL amyloidosis — incidence 8 to 12 per million per year; cardiac involvement in about half at diagnosis; slight male predominance; usually a lambda clone.^[3]
• ATTR wild-type — underdiagnosed; autopsy prevalence around 25 percent in those over 80; elderly men with HFpEF, bilateral carpal tunnel, spinal stenosis or biceps rupture years before the heart.^[9]
• ATTRv V122I — carried by 3 to 4 percent of African Americans; penetrant cardiac amyloid in late life; the classic "hypertensive heart failure" mislabel.^[3]
• Cardiac sarcoidosis — clinical involvement in 2 to 5 percent of systemic sarcoid, subclinical in 20 to 25 percent on PET or autopsy; over-represented in African Americans, Scandinavians and Japanese; young and middle-aged adults.^[11]
• Endomyocardial fibrosis — the tropical equatorial belt (Uganda, Nigeria, Mozambique, the Kerala coast); a leading cause of heart failure in young people there, with eosinophilia and poverty as risk factors.^[7]
• Hereditary haemochromatosis — HFE C282Y homozygosity in 1 in 200 Northern Europeans; cardiac deposition in about a third of untreated adults.^[8]

Read the bedside like the consultant — the JVP and the systemic clues

The JVP is the most important bedside sign, and the waveform tells you more than the height. In RCM the y descent is rapid and deep (Friedreich's sign) — early diastolic filling is fast, then arrested — alongside a preserved x descent. Kussmaul's sign sits on top, marking the stiff right ventricle that cannot accept venous return.^[6]

Heart sounds split RCM from constriction at the bedside. An S3 in RCM marks the rapid deceleration of early filling; the pericardial knock of constriction is its higher-pitched, earlier mirror — filling arrested by the pericardium itself. An S4 appears while the atrium still contracts in sinus rhythm.^[1]

Then hunt for the cause in the skin, mouth and hands — the systemic clues that hand you the aetiology before any scan.^[1]

• Tongue — macroglossia with teeth scalloping (AL); eyelids — periorbital purpura, the raccoon sign (AL).
• Skin — bronze pigmentation and angiokeratomas (haemochromatosis, Fabry); wrists and shoulders — carpal tunnel and biceps tendon rupture (ATTR).
• Joints — second and third metacarpophalangeal arthritis (haemochromatosis); lymph nodes, skin and eyes — erythema nodosum and uveitis (sarcoid).^[1]

Phenotype, then constrict, then cause — the staged diagnostic strategy

Run the work-up in three deliberate steps, in order. Confirm the restrictive phenotype, separate it from constriction, then name the infiltrate. Skipping straight to a biopsy without the first two is how patients reach an operating table they should never have been on.^[1][5]

Step one — phenotype, on ECG and echo. Low limb-lead voltages under 0.5 mV with a thick granular LV, a pseudoinfarct Q-wave pattern with no infarct, and first-degree or higher AV block build the amyloid case. Echo shows massive bi-atrial enlargement and an E-dominant restrictive inflow — E-over-A above 2, deceleration time under 150 ms — with an annular e-prime under 5 cm/s at both septal and lateral walls.^[1]

Step two — separate from constriction. BNP is markedly raised in RCM and normal in constriction; pericardial calcification and septal bounce belong to constriction alone; annulus paradoxus (preserved septal e-prime) points to constriction. On simultaneous catheter tracings the dip-and-plateau appears in both, but in RCM LVEDP exceeds RVEDP by over 5 mmHg at end-expiration while in constriction they equalise within 5 mmHg.^[6]

Step three — name the infiltrate, with the modality matched to the cause.^[1]

• Cardiac MRI — diffuse subendocardial LGE that will not null, native T1 over 1040 ms and extracellular volume over 40 percent for amyloid; patchy basal subepicardial LGE with FDG uptake for sarcoid; native T2-star under 20 ms for iron.^[8]
• Bone-tracer scintigraphy (PYP, DPD or HMDP) at Perugini grade 2 to 3 diagnoses ATTR non-invasively, once light chains are excluded.^[12]
• Serum free light chains with ratio, serum and urine immunofixation, bone marrow biopsy find the AL clone.^[3]
• Endomyocardial biopsy with Congo red and apple-green birefringence plus mass-spectrometry typing remains the gold standard when non-invasive work-up is inconclusive.^[1]

^{[6] [21] [22] [2] [9] [14] [15] [16]}

Treat the cause — and never reach for digoxin or a calcium-channel blocker

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The single most important step in RCM is to treat the underlying cause; everything else is symptomatic. Modern therapy has transformed the prognosis of AL and ATTR amyloid, which is exactly why early, accurate typing now changes lives.^[1][3]

ATTR amyloidosis — tafamidis. In ATTR-ACT, 441 patients with transthyretin amyloid cardiomyopathy were randomised 2:1:2 to tafamidis 80 mg, tafamidis 20 mg, or matching placebo for 30 months; tafamidis binds transthyretin and prevents tetramer dissociation, and the trial hierarchically reduced all-cause mortality (hazard ratio 0.70) and cardiovascular-related hospitalisations. The licensed maintenance dose is a single 61 mg capsule orally once daily.^[2][16]

AL amyloidosis — urgent plasma-cell-directed chemotherapy, never tafamidis. Treatment aims to eliminate the plasma-cell clone: the combination of CyBorD — cyclophosphamide, bortezomib and dexamethasone — is the most widely used regimen and a standard of care, and daratumumab, an anti-CD38 monoclonal antibody, is added on the evidence of the phase-3 randomised ANDROMEDA trial. Tafamidis has no place here — it stabilises transthyretin, not a plasma-cell clone.^[13]

Cardiac sarcoidosis — immunosuppression, corticosteroids first. Immunosuppressive treatment, particularly corticosteroids, is the cornerstone of therapy for cardiac sarcoidosis; steroid-sparing agents are used for refractory disease or steroid toxicity. Diagnosis leans on imaging, because the endomyocardial biopsy that is the gold standard has low sensitivity — involvement is focal and patchy: FDG-PET and cardiac MRI both aid the diagnosis and track treatment response and prognosis. Implantable devices cover the arrhythmia risk — high-grade conduction block and ventricular arrhythmias.^[18]

Hereditary haemochromatosis — get the iron out. Phlebotomy is the mainstay of treatment for hereditary haemochromatosis; iron chelation therapy is the mainstay when phlebotomy cannot be used and for secondary iron overload. EASL sets the treatment target for phlebotomy as a serum ferritin under 50 microgram per litre during the induction phase and under 100 microgram per litre during the maintenance phase. Iron-overload cardiomyopathy is potentially reversible if effective therapy starts before overt heart failure.^[8][15]

Endomyocardial disease. Löffler endocarditis is the cardiac phenotype of the hypereosinophilic syndromes, characterised by endomyocardial fibrosis and intracardiac thrombosis. When it is driven by the FIP1L1-PDGFRA fusion the disease is exquisitely sensitive to imatinib, and anticoagulation is part of management when intracardiac thrombus forms. Carcinoid heart disease progressively fibroses the right-sided valves: somatostatin analogues are the cornerstone of medical management of the carcinoid syndrome, but there is no evidence they influence the development or progression of the cardiac disease, and valve surgery is the only definitive treatment.^[7][17][19]

The preventable-harm list — drugs you must not give in amyloidosis

Identifying the amyloid nature of a cardiomyopathy changes the prescription immediately — several drug classes come off the list. Teach the team why before the next drug round.^[22]

• Digoxin is contraindicated once the amyloid nature of a cardiomyopathy is identified, as are calcium-channel blockers and beta-blockers — identifying the amyloid has a direct therapeutic implication.^[22]
• Non-dihydropyridine calcium-channel blockers — verapamil and diltiazem — sit on that same contraindicated list.^[22]
• Over-diuresis and vasodilators collapse a preload-dependent ventricle into cardiogenic shock — nitrates, ACE inhibitors, ARBs and hydralazine have no place in decompensated RCM.^[10]

Diurese with your eyes open — the ventricle is preload-dependent

Acute decompensated RCM is a difficult combination — marked congestion, hypotension and renal dysfunction on a ventricle that cannot afford to lose preload. Cautious intravenous loop diuretic is the mainstay, titrated to urine output and renal function.^[10]

• Cautious intravenous loop diuretic is the mainstay for congestion, titrated to urine output and renal function; the ventricle is preload-dependent, so over-diuresis is a real risk.^[10]
• Beta-blockers and calcium-channel blockers are contraindicated once amyloid is identified.^[22]
• Atrial fibrillation with rapid ventricular response — rate control cautiously, avoiding digoxin and the calcium-channel blockers; atrial arrhythmia was the presenting feature in 62 percent of one ATTRwt cohort.^[9][22]

Pacemakers, ICDs and the combined heart-liver transplant

Devices follow the rhythm; transplantation follows the cause. A pacemaker covers symptomatic high-grade AV block, common in sarcoid and amyloid; an ICD covers sustained VT, with primary-prevention benefit weighed against competing risk in end-stage amyloid.^[1]

Heart transplantation gives a 5-year survival of 70 to 80 percent in selected end-stage RCM with a treatable or absent extra-cardiac cause. For ATTRv the liver is the source of mutant transthyretin, so a combined heart-liver transplant prevents recurrence; for AL with renal failure a combined heart-kidney transplant is the equivalent move.^[1]

The tropical and the temperate — EMF and Löffler

Endomyocardial disease is the great tropical cause of restrictive physiology, and Löffler is its temperate mirror. Both scar the endocardium and coat it with thrombus, producing the pathognomonic apical obliteration of one or both ventricles on echo — the cavity filled in from the apex upwards.^[7]

Tropical endomyocardial fibrosis dominates the equatorial belt — Uganda, Nigeria, Mozambique, the Kerala coast — and is a leading cause of heart failure in young people there. The giveaway at the bedside is ascites out of proportion to the peripheral oedema, with AV-valve regurgitation from tethered leaflets. Endocardiectomy with valve repair offers symptomatic relief in selected patients.^[7]

Löffler endocarditis is the temperate-zone hypereosinophilic syndrome — marked peripheral eosinophilia over 1500 per microlitre for over 6 months, endocardial thrombus, systemic thromboembolism and restrictive filling, often driven by FIP1L1-PDGFRA. Treat the eosinophilia with steroids, hydroxyurea or imatinib, anticoagulate, and reserve surgical endocardiectomy for advanced disease.^[7]

Prognosis is cause-dependent — and it has been transformed

Prognosis tracks the cause, and modern therapy has rewritten it for AL and ATTR. Knowing the type tells you the timeline before you say a word about treatment.^[1]

• AL amyloidosis — biomarker stage sets the timeline: the revised Mayo staging (difference between involved and uninvolved free light chains, troponin T and NT-proBNP) gives median overall survivals of 94.1, 40.3, 14 and 5.8 months for stages I to IV.^[14]
• ATTR wild-type — median overall survival 3.6 years from diagnosis; tafamidis reduced all-cause mortality (hazard ratio 0.70) over 30 months in ATTR-ACT.^[2][9]
• ATTRv Val122Ile — population carrier frequency 3 to 4 percent among individuals of African ancestry; causes transthyretin misfolding and hereditary amyloidosis.^[20]
• Cardiac sarcoidosis — can present as life-threatening arrhythmias, severe heart failure or sudden cardiac death; corticosteroids are the cornerstone of therapy.^[18]
• Tropical EMF — outcomes remain poor, though survival has increased with medical heart-failure treatment and more tailored surgery.^[7]
• Hereditary haemochromatosis — iron-overload cardiomyopathy is potentially reversible if effective therapy starts before overt heart failure.^[8]

Special populations — who you screen, and how

Screening thresholds shift with ancestry, age and geography. Build the reflex into the history so the diagnosis finds you, not the other way around.^[1]

• Elderly — ATTR wild-type dominates; suspect it in any man over 65 with "HFpEF" and bilateral carpal tunnel or biceps rupture, and send bone-tracer scintigraphy and serum free light chains at a low threshold.^[9]
• African descent — screen TTR V122I in any patient presenting with "hypertensive heart failure" and LVH out of proportion; the carrier rate is 3 to 4 percent.^[3]
• Tropical regions — EMF is the dominant cause and tuberculous constrictive pericarditis the dominant mimic; both are common.^[7]
• Pregnancy — rare; avoid ACE inhibitors, ARBs and spironolactone, diurese cautiously with furosemide, and deliver in a cardiac centre.^[10]
• Family screening — offer genetic testing to all first-degree relatives of ATTRv patients and to siblings of HFE C282Y haemochromatosis; cascade screening finds pre-symptomatic carriers.^[1][8]

The guideline and trial backbone

Three documents and one trial carry the evidence weight in RCM. Name them in the viva and the marks follow.^[1]

• 2021 ESC position statement on cardiac amyloidosis (Garcia-Pavia) — proposes invasive and non-invasive definitions, clinical scenarios to suspect the disease, a diagnostic algorithm, and how to monitor and treat it.^[1]
• 2021 expert consensus on monitoring ATTR-CM (Garcia-Pavia) — 11 measurable features across three domains, with proposed thresholds and monitoring frequency.^[12]
• 2016 ESC heart-failure guideline (Ponikowski) — the diagnosis and treatment of acute and chronic heart failure.^[10]
• ATTR-ACT (Maurer 2018) — 441 patients randomised 2:1:2 to tafamidis 80 mg, tafamidis 20 mg or placebo for 30 months; hierarchical primary analysis of all-cause mortality then cardiovascular-related hospitalisations.^[2]
• ANDROMEDA (Theodorakakou 2021) — the phase-3 randomised trial of daratumumab plus CyBorD versus CyBorD in newly diagnosed AL amyloidosis.^[13]
• HRS 2014 expert consensus on cardiac sarcoidosis (Birnie) — diagnosis and management of arrhythmias associated with cardiac sarcoidosis.^[11]
• Revised Mayo AL staging (Kumar 2012) — free-light-chain difference, troponin T and NT-proBNP create stages I to IV with median survivals of 94.1 to 5.8 months.^[14]
• When to suspect amyloidosis (Law and Gillmore 2022) — bone scintigraphy and CMR as the sensitive and specific imaging modalities, and the validated non-biopsy criteria for ATTR-CM.^[21]

Ward-round test — 3 stems

Work each stem out loud, then open the model answer. Each one rehearses a trap that costs marks.^[1]

Stem 1 — the elderly man with refractory HFpEF and bilateral carpal tunnelShowHide

A 74-year-old man is admitted for the third time with "HFpEF" that will not settle. His ECG voltages are tiny, the echo shows a thick granular LV with an apical-sparing strain pattern, and he has bilateral carpal tunnel releases in his history. What two tests settle the diagnosis, and what drug do you reach for first? Model: Send work-up to exclude the other amyloid types and a bone-tracer scintigraphy scan — bone scintigraphy with CMR is the highly sensitive and specific imaging route, and ATTR-CM is the one amyloid type that can be diagnosed by validated non-biopsy criteria in the majority. If ATTR-CM is confirmed, start tafamidis — the licensed dose is 61 mg once daily; in ATTR-ACT tafamidis reduced all-cause mortality (hazard ratio 0.70) and cardiovascular-related hospitalisations over 30 months. Digoxin, calcium-channel blockers and beta-blockers are contraindicated once amyloid is identified, and this patient is not a pericardiectomy candidate.^{[2][16][21][22]}

Stem 2 — raised JVP, Kussmaul and a preserved EFShowHide

A 60-year-old woman has a JVP that does not fall, a positive Kussmaul sign, hepatomegaly, ascites and a preserved ejection fraction. Is this restriction or constriction, and which three tests discriminate? Model: The bedside signs overlap completely — Kussmaul and the dip-and-plateau sign appear in BOTH, so they do not discriminate. The three tests that do are BNP (markedly raised in restriction, normal in constriction), pericardial calcification on CT (present in constriction, never in RCM) and annulus paradoxus on tissue Doppler (preserved septal e-prime in constriction, reduced in both walls in RCM). On catheter, LVEDP exceeding RVEDP by over 5 mmHg points to restriction; equalisation within 5 mmHg points to constriction. The decision matters because pericardiectomy cures constriction and is harmful in RCM.^[6]

Stem 3 — the young African-descent patient with AV blockShowHide

A 34-year-old man of African descent presents with complete heart block and an episode of sustained ventricular tachycardia, mild biventricular failure and bilateral hilar lymphadenopathy. What is the diagnosis, and what is the first treatment? Model: This is cardiac sarcoidosis until proven otherwise — high-grade conduction block and ventricular arrhythmias are its classic complications. Endomyocardial biopsy is the gold standard but insensitive because involvement is focal and patchy, so confirm with cardiac MRI and FDG-PET, which also track treatment response. First treatment is immunosuppression with corticosteroids, and consider device therapy for the sustained ventricular tachycardia.^[18]

The mantra

Stiff ventricle, preserved EF, bi-atrial enlargement — find the cause, never digoxin or a calcium-channel blocker, never pericardiectomy.^[1][6]

References22ShowHide

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2. [2]Maurer MS, Schwartz JH, Gundapaneni B, et al. Tafamidis Treatment for Patients with Transthyretin Amyloid Cardiomyopathy N Engl J Med, 2018.PMID 30145929
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19. [19]Luo R, Qi X Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (FIP1L1::PDGFRA) complicated by Loeffler's endocarditis leading to stroke BMC Neurol, 2026.PMID 42135668
20. [20]Parcha V, Malla G, et al. Association of Transthyretin Val122Ile Variant With Incident Heart Failure Among Black Individuals JAMA, 2022.PMID 35377943
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22. [22]Laraki R, et al. [Cardiac amyloidosis. General review] Rev Med Interne, 1994.PMID 8059146