Constrictive Pericarditis vs Restrictive Cardiomyopathy

 

Constrictive Pericarditis vs Restrictive Cardiomyopathy

A Practical, Clinically Oriented Comparison

Constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM) present with remarkably similar clinical features—predominantly right-sided heart failure with preserved or near-preserved systolic function. Despite this overlap, the underlying pathology, diagnostic clues, and management strategies differ fundamentally. Accurate distinction is critical because constrictive pericarditis is potentially curable, while restrictive cardiomyopathy usually requires long-term medical therapy or advanced heart failure interventions.

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Pathophysiologic Basis

Constrictive pericarditis is caused by a rigid, often thickened or calcified pericardium that limits diastolic expansion of the heart. Ventricular filling becomes abruptly halted in mid-diastole, leading to exaggerated ventricular interdependence and marked respiratory variation in intracardiac flows.

Restrictive cardiomyopathy, in contrast, is a myocardial disease. The ventricles are stiff due to infiltration (e.g., amyloidosis), fibrosis, or hypertrophy, resulting in impaired diastolic relaxation without an external constraint. Ventricular interdependence is minimal, and respiratory variation is blunted.

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Clinical Examination

In constrictive pericarditis, classic physical findings include:

Positive Kussmaul sign (rise or lack of fall in JVP with inspiration)

Absent or poorly palpable apical impulse

Early diastolic pericardial knock due to abrupt cessation of ventricular filling

In restrictive cardiomyopathy:

Kussmaul sign may be present or absent

PMI is often forceful

Third and fourth heart sounds may be heard

Systolic murmurs of mitral or tricuspid regurgitation are more common due to annular dilation

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Electrocardiographic Features

Constrictive pericarditis

Low QRS voltage may be seen

ECG is often otherwise unremarkable

Restrictive cardiomyopathy

Low voltage is typical in infiltrative forms, especially amyloidosis

Conduction abnormalities, atrial arrhythmias, and AV block are more frequent

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Echocardiographic Hallmarks

Echocardiography is central to differentiation.

Respiratory Variation

CP: Marked respirophasic variation (25–40%) in trans-valvular Doppler flows

Inspiration increases tricuspid inflow and decreases mitral inflow

RCM: <10% respiratory variation

Tissue Doppler Imaging

CP: Preserved or increased medial mitral annular e′ velocity (>12 cm/s), reflecting normal myocardial relaxation (“annulus paradoxus”)

RCM: Reduced e′ velocity (<8 cm/s), indicating intrinsic myocardial dysfunction

Additional Echocardiographic Clues

CP

Septal bounce in early diastole

Expiratory hepatic vein diastolic flow reversal

Normal ventricular wall thickness

RCM

Biatrial enlargement (a key feature)

Inspiratory hepatic vein flow reversal

Increased ventricular wall thickness in infiltrative diseases

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CT and Cardiac MRI

Constrictive pericarditis

Thickened or calcified pericardium

Pericardial enhancement on MRI may suggest active inflammation

Restrictive cardiomyopathy

Normal pericardium

Myocardial late gadolinium enhancement patterns help identify infiltrative or fibrotic etiologies

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Biomarkers

CP: NT-proBNP levels are variable and often lower than expected for the degree of congestion

RCM: NT-proBNP is typically markedly elevated, reflecting myocardial involvement and high filling pressures

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Hemodynamic Assessment on Cardiac Catheterization

Invasive hemodynamics remain the gold standard when noninvasive tests are inconclusive.

Shared Features

Elevated and near-equal diastolic pressures

Prominent x and y descents in atrial pressure tracings

Dip-and-plateau (square root) sign in ventricular pressure curves

(more pronounced in constriction)

Distinguishing Findings

Constrictive pericarditis

LVEDP ≈ RVEDP

RV systolic pressure usually <55 mmHg

Discordance of LV and RV systolic pressures with respiration

(LV pressure falls while RV pressure rises during inspiration)

Systolic area index >1.1 (highly specific)

Restrictive cardiomyopathy

LVEDP > RVEDP (especially with volume loading)

RV systolic pressure often ≥55 mmHg

Concordant LV and RV systolic pressure changes during respiration

Systolic area index ≤1.1

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Endomyocardial Biopsy

Constrictive pericarditis: Usually normal myocardium

Restrictive cardiomyopathy: May reveal a specific etiology such as amyloid deposition, fibrosis, or storage disease

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Therapeutic and Prognostic Implications

This distinction has major management consequences:

Constrictive pericarditis can be definitively treated with pericardiectomy, offering symptomatic relief and potential cure.

Restrictive cardiomyopathy is managed with diuretics, rate control, and treatment of the underlying cause; prognosis depends on etiology and disease progression.

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Key Take-Home Points

Think pericardium in constrictive pericarditis and myocardium in restrictive cardiomyopathy.

Respiratory variation and preserved e′ velocity strongly favor constriction.

Biatrial enlargement, reduced e′ velocity, and markedly elevated NT-proBNP suggest restriction.

Cardiac catheterization remains the definitive test when uncertainty persists.

Correct diagnosis directly alters management and outcomes.

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Understanding these nuances allows clinicians to confidently differentiate two clinically similar but fundamentally different diseases, ensuring timely and appropriate treatment.