Restrictive vs Constrictive Cardiomyopathy

Restrictive vs Constrictive Cardiomyopathy: A Complete, Clinician-Friendly Comparison

Restrictive cardiomyopathy (RCM) and constrictive pericarditis (CP) often present with similar clinical features—especially right-sided heart failure with preserved ejection fraction. Yet their underlying pathology, diagnostic clues, and management differ drastically. Distinguishing the two is crucial because RCM is a myocardial disease, while CP is a potentially reversible pericardial disorder.

This article provides a crisp, high-yield comparison for clinicians.

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🔹 1. Definition

Restrictive Cardiomyopathy (RCM)

A myocardial disorder characterized by stiff, non-compliant ventricles due to infiltration or fibrosis.

→ Filling is restricted, systolic function usually preserved until late.

Constrictive Pericarditis (CP)

A pericardial disease in which a thickened, fibrotic, or calcified pericardium limits ventricular expansion.

→ Ventricles cannot fill normally due to an external shell.

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🔹 2. Etiology

RCM Causes

Amyloidosis (most common)

Hemochromatosis

Sarcoidosis

Endomyocardial fibrosis

Radiation-induced myocardial disease

Idiopathic or familial RCM

CP Causes

Tuberculosis (common in developing regions)

Viral pericarditis

Post-cardiac surgery

Radiation therapy

Connective tissue disorders

Idiopathic chronic pericarditis

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🔹 3. Pathophysiology (Key Difference)

RCM

Stiff myocardium → impaired ventricular compliance

Affects both ventricles symmetrically

Normal pericardium

Atrial enlargement is prominent

CP

Rigid pericardium → ventricles cannot expand

Ventricular interdependence (classic)

Dissociation between thoracic and intracardiac pressures

Atria may be less dilated than in RCM

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🔹 4. Clinical Features

Both conditions show:

Elevated JVP

Right-sided heart failure

Preserved EF

Kussmaul’s sign

But subtle differences help:

RCM

More pulmonary congestion

More severe exercise intolerance

S3 may be heard

Atrial fibrillation common

LV thickening (infiltrative diseases)

CP

Pericardial knock (early diastolic sound)

Peripheral edema often more pronounced

Ascites and hepatomegaly prominent

Cachexia in chronic cases

History of TB, surgery, or radiation

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🔹 5. Investigations

ECG

RCM:

Low voltage (amyloidosis)

Conduction abnormalities

Atrial enlargement

Arrhythmias common

CP:

Low voltage rare

AF common

Non-specific ST-T changes

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Echocardiography

RCM

Normal or thickened ventricles

Marked biatrial enlargement

Normal pericardium

Doppler: restrictive filling pattern without respiratory variation

CP

Normal LV size

Septal “bounce” or “shudder”

Respiratory variation in mitral/tricuspid inflow

Inferior vena cava dilated, poor collapse

Thickened pericardium (sometimes missed)

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Cardiac MRI

RCM

Myocardial infiltration

Late gadolinium enhancement (LGE) in typical patterns

Normal pericardium

CP

Thickened or calcified pericardium

Ventricular interdependence

Septal bounce

Real-time cine sequences show dissociation of pressures

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Hemodynamics (Cardiac Catheterization)

RCM

No ventricular interdependence

Elevated LVEDP = RVEDP (nearly equal)

Square root sign present in some cases

Pulmonary pressures higher than in CP

CP

Marked ventricular interdependence (KEY)

Equalization of diastolic pressures (within 5 mmHg)

Prominent square root sign

Discordant LV/RV systolic pressures with respiration (defining feature)

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🔹 6. Management

RCM

Treat underlying cause

Diuretics for congestion

Avoid aggressive preload reduction

Disease-specific therapies:

Tafamidis (ATTR amyloidosis)

Iron chelation (hemochromatosis)

Steroids (sarcoidosis if active)

Advanced cases: heart transplant

CP

Diuretics temporarily

Definitive treatment: Pericardiectomy

Excellent prognosis if performed early

Avoid in active inflammatory phase (unless unavoidable)

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🔹 7. Prognosis

RCM

Progressive, worse long-term survival

Depends on etiology

Amyloidosis particularly poor without targeted therapy

CP

Potentially curable

Post-pericardiectomy survival improves dramatically

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🔻 Quick Summary Table

Feature Restrictive Cardiomyopathy Constrictive Pericarditis

Primary problem Myocardium stiff Pericardium rigid

Ventricular interdependence Absent Present

Pericardial thickness Normal Thickened / calcified

Atria Marked enlargement Mild–moderate enlargement

ECG Low voltage (amyloid) Usually normal voltage

Echo hallmark Biatrial enlargement Septal bounce + respiratory variation

Catheter hallmark No discordance Ventilatory discordance

Treatment Disease specific ± transplant Pericardiectomy (curative)

Prognosis Chronic progressive Often reversible

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Final Takeaway

RCM and CP may look alike, but one is a myocardial disease with limited treatment options, while the other is a mechanical pericardial disease that can be surgically cured.

Accurate differentiation using echo, MRI, and invasive hemodynamics is essential for delivering the correct therapy.