What are the typical ECHO (Echocardiography) findings in cardiac amyloidosis?

Echocardiographic Findings in Cardiac Amyloidosis

Echocardiography reveals a constellation of structural and functional abnormalities in cardiac amyloidosis, with the hallmark finding being increased left ventricular wall thickness (≥12 mm) combined with a small LV cavity, biatrial enlargement, and a characteristic apical sparing pattern on longitudinal strain imaging. 1

Structural Abnormalities

Left Ventricular Changes

• Increased LV wall thickness ≥12 mm is the cardinal structural finding, often presenting with concentric hypertrophy and a small cavity size 1, 2
• The myocardial walls frequently demonstrate a "granular sparkling" or hyperechogenic appearance (present in 55-89% of cases), corresponding to scattered amyloid deposits histopathologically 1, 3
• This granular appearance, while characteristic, is not universally present and does not correlate with specific amyloid subtypes 3

Atrial and Valvular Involvement

• Biatrial enlargement is present in 89% of cases and is typically disproportionate to the degree of ventricular dysfunction 1, 4
• Thickened cardiac valves without significant stenosis are characteristic, along with increased atrial septal thickness 1, 2
• Right ventricular free wall thickening is commonly observed and should raise suspicion when present with LV hypertrophy 1, 4

Pericardial Findings

• Pericardial effusion occurs in approximately 67% of cases, typically small and generalized 1, 3

Functional Abnormalities

Diastolic Dysfunction

• Restrictive transmitral Doppler filling pattern is the hallmark functional abnormality, characterized by markedly elevated E wave, reduced A wave, and decreased deceleration time 1
• 69-100% of patients demonstrate restrictive filling patterns (E/A ≥2.0, E/e' ≥15), reflecting severe diastolic dysfunction 5, 4, 6
• Reduced E' wave velocity on tissue Doppler imaging indicates impaired myocardial relaxation 1

Systolic Function and Strain Imaging

• LV ejection fraction is typically preserved or only mildly reduced (mean 49-50%) until late-stage disease, despite significant myocardial infiltration 5, 4, 6
• Reduced longitudinal strain with apical sparing pattern is highly characteristic, with an apical-to-basal strain ratio >2.1 being highly suggestive of cardiac amyloidosis 1, 2
• All patients with biopsy-proven cardiac amyloidosis demonstrate apical sparing on longitudinal strain echocardiography when deformation imaging is performed 4
• The "bulls-eye" appearance on strain mapping, showing preserved apical function with impaired mid-basal segments, is typical 1
• LV ejection fraction-to-strain ratio >4 is a notable diagnostic feature 1, 2

Tissue Doppler Findings

• Decreased S' wave measurement on lateral wall tissue Doppler imaging reflects impaired longitudinal systolic function 1
• Tissue Doppler can detect subtle changes in both systolic and diastolic function that cannot be detected by conventional Doppler flow measurements 5

Critical Diagnostic Integration

ECG-Echo Discordance

• The combination of low QRS voltage on ECG with increased LV wall thickness on echo (>12 mm) is particularly useful for raising clinical suspicion, as this voltage-to-mass discordance is highly specific for infiltrative disease 1, 2, 7, 8
• Low voltage is present in approximately 25% of ATTR and 50% of AL amyloidosis cases 8

Temporal Evolution

• Serial echocardiography reveals that cardiac amyloidosis initially manifests as diastolic LV dysfunction rather than systolic dysfunction 3
• The final stage is characterized by severe impairment of both systolic and diastolic functions 3
• Reduced LV distensibility occurs in 78-100% of cases, while reduced contractility appears later (22-44%) 3

Important Clinical Caveats

Limitations of Echocardiography

• Echocardiography cannot distinguish AL (light chain) from ATTR (transthyretin) cardiac amyloidosis, requiring further testing with monoclonal protein screening and/or nuclear imaging for subtype determination 2, 7
• When echocardiography shows suggestive findings, proceed immediately with monoclonal protein screening (serum/urine immunofixation, free light chains), NT-proBNP, troponin, and nuclear imaging with bone tracers for ATTR diagnosis 2, 7

Advanced Techniques

• Speckle-tracking analysis is recommended by multiple international guidelines as part of comprehensive echocardiographic evaluation and provides superior functional and prognostic information compared to tissue Doppler imaging 2, 5
• LV longitudinal strain and cyclic variation of myocardial integrated backscatter may be the best predictors of adverse outcomes 6

When to Proceed to Advanced Imaging

• Cardiac MRI should be performed when echocardiography shows suggestive but not definitive findings to enable tissue characterization and differentiate amyloidosis from other causes of LV hypertrophy 2, 7
• The European Society of Cardiology proposes an Integrated Wall Thickness (IWT) echocardiographic score, where values ≥8 combined with positive bone scintigraphy can be diagnostic of ATTR cardiac amyloidosis 2