What are the recommended guidelines for performing speckle‑tracking strain analysis on two‑dimensional echocardiography?

Guidelines for Strain Analysis in 2D Echocardiography

Two-dimensional speckle-tracking echocardiography (2D STE) is reproducible and feasible for clinical use, with global longitudinal strain (GLS) being the most validated parameter, though vendor-specific reference values must be applied due to lack of universal standardization. 1

Image Acquisition Requirements

Optimize Image Quality

• Maximize left ventricular areas while avoiding foreshortening, which results in volume underestimation and affects strain measurements 1
• Acquire images from apical four-chamber and two-chamber views as the standard approach 1
• Maintain frame rates between 50-80 frames per second for optimal speckle tracking 2
• Ensure the entire cardiac structure is contained within the imaging sector throughout the cardiac cycle 1

Use Contrast Enhancement When Needed

• Apply contrast agents when two or more contiguous LV endocardial segments are poorly visualized in apical views 1
• Contrast-enhanced images provide volumes closer to cardiac magnetic resonance measurements 1

Technical Execution for Strain Analysis

Region of Interest (ROI) Placement

• Limit the ROI width to the myocardium only, excluding the pericardium 1
• For right ventricular strain, avoid placing basal reference points too low (on the atrial side of the tricuspid annulus), as this produces artifactually low basal strain values 1
• This is particularly challenging with the thin RV free wall 1

View Selection

• Measure RV longitudinal strain in the RV-focused four-chamber view 1
• For LV strain, use apical four-chamber, two-chamber, and three-chamber views for comprehensive GLS assessment 1

Interpretation and Reference Values

Left Ventricular Global Longitudinal Strain

• GLS should be obtained and reported whenever possible to provide quantitative analysis of LV longitudinal function 1
• GLS is accurate in early detection of subclinical alterations in LV function before ejection fraction impairment 1
• GLS has demonstrated high feasibility, reproducibility, and incremental predictive value in clinical practice 1, 3

Right Ventricular Strain

• Normal RV free wall strain: -29 ± 4.5% 1
• Abnormal threshold: > -20% (i.e., <20% in absolute magnitude) 1
• RV free wall plus septal strain averages -21% 1
• RV GLS has prognostic value in heart failure, acute myocardial infarction, pulmonary hypertension, amyloidosis, and predicting RV failure after LV assist device implantation 1

Critical Distinction in RV Strain Reporting

• The term "RV GLS" refers to either the average of RV free wall and septal segments OR RV free wall segments alone 1
• Until universal standards are established, interpretation must account for methodology and vendor-specific reference values 1
• Note that RV longitudinal strain is significantly higher in absolute value than strain averaged from both septal and free wall segments 1

Advantages and Limitations

Key Advantages

• Angle-independent measurement (unlike Doppler-based techniques) 1, 4, 5
• Less confounded by overall heart motion compared to TAPSE or S' velocity 1
• Objective quantification of myocardial deformation 4, 5
• High reproducibility when properly performed 1, 3

Important Limitations and Pitfalls

• Vendor dependency remains a significant issue - different manufacturers produce different values 1
• Image quality dependency: affected by reverberation, artifacts, and attenuation 1
• Load dependency: strain measurements depend on loading conditions as well as chamber size and shape 1
• No definite universal reference ranges currently recommended for RV strain due to need for additional normative data from large multi-vendor studies 1

Training Requirements

• A minimum of 50 studies is required to achieve expert competency (intraclass correlation coefficient >0.9) in GLS analysis 6
• This training period typically spans 3 months 6
• Prior background knowledge in echocardiography significantly affects the learning curve for interobserver reproducibility and time efficiency 6
• Short-axis strain analysis (global circumferential and radial strain) has a steeper learning curve and may not reach expert level with standard training 6

Reporting Standards

• Always report reference normal values derived from ASE/EACVI recommendations to differentiate normal from pathological conditions 1
• Avoid surveillance of specific variables using different ultrasound techniques over time 1
• Document vendor type and model, as strain values vary between systems 1, 2
• Because of vendor variability in speckle-tracking analysis, there is no clear universal cutoff value 1