Can elevated wall thickness be seen in sarcoidosis and amyloidosis?

Elevated Wall Thickness in Sarcoidosis and Amyloidosis

Yes, elevated wall thickness can be seen in both cardiac sarcoidosis and cardiac amyloidosis, though the pattern, mechanism, and temporal characteristics differ significantly between these two infiltrative cardiomyopathies.

Cardiac Amyloidosis and Wall Thickness

Cardiac amyloidosis characteristically produces concentric thickening of the ventricles, atria, interatrial septum, and valves 1. The diagnostic criteria specifically define increased wall thickness as left ventricular wall thickness >12 mm with no other known cardiac cause 1.

Key Features of Amyloid Wall Thickening:

• Concentric pattern affecting multiple cardiac structures including ventricles, atria, interatrial septum, and valves 1
• Increased interatrial septum thickness is a specific echocardiographic feature suggesting amyloidosis 1
• Increased AV valve thickness helps differentiate amyloidosis from other causes of hypertrophy 1
• The wall thickening is progressive and persistent, reflecting ongoing amyloid protein deposition 1

Important Caveat:

Not all cardiac amyloidosis presents with increased wall thickness. A recent study found that 9% of cardiac amyloidosis patients had wall thickness <12 mm, all with AL-type amyloidosis 2. These patients still had clinically significant disease with elevated cardiac biomarkers and similar outcomes to those with increased wall thickness 2. This means diagnostic algorithms should not exclude cardiac amyloidosis based solely on normal wall thickness 2.

Cardiac Sarcoidosis and Wall Thickness

Cardiac sarcoidosis demonstrates wall thickening primarily in the acute/active inflammatory stage, with a distinctly different temporal pattern than amyloidosis 1.

Acute Stage Characteristics:

• Wall thickening occurs due to granulomatous inflammation and edema 1
• High T2 signal on MRI reflects active inflammation 1
• Biventricular involvement is more common than in amyloidosis 1
• Increased RV free wall thickness is a distinguishing feature 1

Chronic Stage Evolution:

In contrast to amyloidosis, chronic cardiac sarcoidosis typically shows wall thinning rather than thickening 1. The chronic stage is characterized by:

• Wall thinning replacing the earlier thickening 1
• Aneurysm formation in areas of scarring 1
• Regional wall motion abnormalities 1
• Fibrosis with mid-myocardial, subepicardial, or transmural late gadolinium enhancement 1

Critical Distinguishing Features

Pattern of Wall Involvement:

• Amyloidosis: Diffuse, concentric, symmetric thickening that is persistent and progressive 1
• Sarcoidosis: Regional or patchy thickening in acute phase that evolves to thinning in chronic phase 1

Associated Imaging Findings:

Amyloidosis 1:

• Diffuse subendocardial late gadolinium enhancement progressing to transmural
• Dark blood pool on cardiac MRI
• Granular or sparkling myocardial texture on echocardiography 1
• Small pericardial effusion 1

Sarcoidosis 1:

• Patchy, mid-myocardial or subepicardial late gadolinium enhancement
• Preferential involvement of basal septal and lateral walls
• High FDG uptake on PET imaging (90% sensitivity) 3

Clinical Context:

• Amyloidosis patients are typically older (mean age 78 years for ATTR) with restrictive physiology 3
• Sarcoidosis patients are younger (mean age 62 years) with higher rates of ventricular tachycardia (53% vs 11%) and require ICD placement more frequently (66% vs 13%) 3

Diagnostic Pitfalls to Avoid

Do not assume normal wall thickness excludes cardiac amyloidosis, particularly in AL amyloidosis where 9% may present without increased wall thickness 2. Cardiac biomarkers (NT-proBNP, troponin) should be checked regardless of wall thickness 1.

Do not diagnose cardiac sarcoidosis based on wall thickening alone, as this can mimic amyloidosis on echocardiography and even CMR 4. One case report documented a patient with biventricular wall thickening and granular sparkling on echo that appeared consistent with amyloidosis, but endomyocardial biopsy and FDG-PET confirmed sarcoidosis 4.

Advanced imaging is essential for differentiation: Cardiac MRI with late gadolinium enhancement has 75-100% sensitivity for sarcoidosis and 85% sensitivity with 92% specificity for amyloidosis 1, 5. FDG-PET is particularly useful for sarcoidosis (89% sensitivity) and should be pursued when MRI is inconclusive 5.