What is apical sparing on echocardiographic speckle‑tracking strain and what does it indicate?

Apical Sparing on Echocardiographic Strain Imaging

Apical sparing is a pattern on speckle-tracking echocardiography where longitudinal strain is relatively preserved at the left ventricular apex compared to the basal and mid-ventricular segments, creating a characteristic "bulls-eye" or "cherry on top" appearance—this pattern is highly suggestive of cardiac amyloidosis but is not specific to this diagnosis. 1

Definition and Calculation

Apical sparing is quantified using the apical sparing ratio (ASR), calculated as:

ASR = (average apical longitudinal strain) / (average basal + mid-ventricular longitudinal strain)

• ASR >1.0 indicates apical sparing 1, 2
• In normal hearts, longitudinal strain shows a base-to-apex gradient with progressively better (more negative) strain values toward the apex
• In cardiac amyloidosis, this gradient becomes exaggerated, with the base and mid-segments showing markedly impaired strain while the apex remains relatively preserved 3

Clinical Significance for Cardiac Amyloidosis

According to the 2021 ASNC/AHA/ASE expert consensus, relative apical sparing with a ratio >1 is one of the typical echocardiographic features used to diagnose cardiac amyloidosis (both AL and ATTR subtypes) when other causes of these manifestations are reasonably excluded 1.

The visual pattern shows:

• Markedly reduced longitudinal strain in basal and mid-ventricular segments
• Preserved strain at the apex
• A "bulls-eye" appearance on strain mapping with the apex at the center 3

Critical Limitations and Diagnostic Accuracy

However, recent high-quality evidence reveals significant limitations in the specificity of apical sparing:

Poor Positive Predictive Value

• In a 2024 multicentre study of 544 confirmed cardiac amyloidosis patients versus 200 controls with clinical/echocardiographic suspicion but ruled-out amyloidosis, ASR was only 72% sensitive and 66% specific for cardiac amyloidosis 4
• 32% of control patients without cardiac amyloidosis demonstrated apical sparing, and even 6% of healthy subjects showed this pattern 4
• The positive predictive value was only 38.6% in one tertiary care cohort 5
• Another study found only 27-33% of patients with apical sparing had confirmed cardiac amyloidosis 6

Other Conditions Causing Apical Sparing

Apical sparing is NOT specific to cardiac amyloidosis and occurs in:

• Hypertensive left ventricular hypertrophy 4, 7
• Hypertrophic cardiomyopathy 7, 2
• End-stage renal disease 7
• Aortic stenosis 7, 5
• Coronary artery disease (RCA/LCx distribution) 7
• Chemotherapy-induced cardiomyopathy 7
• Reversed Takotsubo syndrome 7

When to Suspect True Cardiac Amyloidosis

Apical sparing is more likely to represent true cardiac amyloidosis when combined with:

1. Increased LV wall thickness (>12 mm, ideally >15 mm) 1, 6

2. Older age (mean age 76 years in confirmed cases vs. 59 years in false positives) 6

3. Additional echocardiographic features:

   • Biatrial enlargement
   • Thickened valve leaflets and interatrial septum
   • Hyperechogenic ("sparkling") myocardium
   • Grade ≥2 diastolic dysfunction
   • Small pericardial effusion 1, 3

4. Clinical red flags:

   • Bilateral carpal tunnel syndrome
   • Biceps tendon rupture
   • Lumbar spinal stenosis
   • Unexplained neuropathy
   • Family history of amyloidosis 3

Diagnostic Algorithm

When apical sparing is identified:

1. Assess LV wall thickness: If <12 mm, cardiac amyloidosis is less likely
2. Evaluate age and clinical context: Older patients with orthopedic manifestations increase probability
3. Look for additional echo features: Multiple findings increase specificity
4. Proceed with definitive testing:
   • 99mTc-PYP/DPD/HMDP scintigraphy (Grade 2-3 uptake diagnostic for ATTR if no monoclonal protein) 1
   • Cardiac MRI (elevated ECV >0.40, diffuse LGE, abnormal gadolinium kinetics) 1
   • Serum/urine immunofixation and free light chains (to exclude AL amyloidosis) 1

Key Clinical Pitfall

The major pitfall is assuming apical sparing equals cardiac amyloidosis. Given that approximately two-thirds of patients with apical sparing do NOT have cardiac amyloidosis 4, 5, 6, this finding should trigger further workup but cannot stand alone as a diagnostic criterion. The diagnostic value depends entirely on the clinical context, with the highest yield in elderly patients with increased wall thickness and suggestive clinical features.

The 2012 study showing 93% sensitivity and 82% specificity 2 used highly selected controls (only hypertrophic cardiomyopathy and aortic stenosis), which does not reflect real-world diagnostic challenges where the differential is much broader 4.