What is the significance and management of abnormal peak longitudinal strain values in assessing cardiac function?

Significance and Management of Abnormal Peak Longitudinal Strain Values

Abnormal peak longitudinal strain (GLS) values below -16% indicate myocardial dysfunction and require further evaluation and management, even when ejection fraction appears normal, as they predict increased risk of heart failure, cardiovascular mortality, and all-cause mortality. 1

Understanding Global Longitudinal Strain

Global longitudinal strain (GLS) is a dimensionless measure of ventricular deformation that provides a more sensitive assessment of cardiac function than traditional ejection fraction measurements. According to current guidelines, GLS values are interpreted as:

• Normal: More negative than -18%
• Borderline: Between -16% and -18%
• Abnormal: Less negative than -16% 1, 2

GLS is particularly valuable because it can detect subclinical myocardial dysfunction before changes in ejection fraction become apparent, making it an early marker of cardiac pathology 1.

Clinical Significance of Abnormal GLS Values

Abnormal GLS values have significant clinical implications:

• Subclinical LV Dysfunction: GLS detects myocardial damage before ejection fraction decline, with longitudinal function impairment preceding circumferential strain alterations 1
• Heart Failure Assessment: GLS is frequently abnormal despite preserved EF in HFpEF patients and provides independent prognostic information in HFrEF patients 1
• Prognostic Value: Each unit decrease in GLS is associated with a 5% increase in risk for adverse cardiac events 3
• Cardiomyopathy Evaluation: In hypertrophic cardiomyopathy, reduced GLS (particularly <15.6%) is independently associated with poor cardiac outcomes and heart failure events 4

Management Algorithm for Abnormal GLS Values

1. Initial Assessment

• Mild Abnormality (GLS -16% to -18%):

  • Review cardiovascular risk factors
  • Consider biomarker testing (troponin, BNP/NT-proBNP)
  • Evaluate for potential causes (hypertension, diabetes, early cardiomyopathy)

• Moderate Abnormality (GLS -14% to -16%):

  • Complete cardiac evaluation including symptoms assessment
  • Biomarker testing (troponin, BNP/NT-proBNP)
  • Consider additional cardiac imaging (stress echocardiography, cardiac MRI)

• Severe Abnormality (GLS worse than -14%):

  • Comprehensive cardiac evaluation
  • Investigation for coronary artery disease
  • Assessment for specific cardiomyopathies
  • Evaluation of valvular heart disease 1

2. Specific Clinical Scenarios

Chemotherapy-Induced Cardiotoxicity

• A 10-15% early reduction in GLS during therapy is the most useful parameter for predicting cardiotoxicity
• A ≥11% relative reduction in GLS predicts subsequent cardiotoxicity
• More frequent monitoring and cardioprotective strategies should be considered 1

Heart Failure with Preserved Ejection Fraction (HFpEF)

• Abnormal GLS with normal EF suggests HFpEF
• Consider diastolic function assessment
• Evaluate for other markers of myocardial dysfunction 5, 1

Coronary Artery Disease

• Segmental longitudinal strain differences can help detect CAD even with preserved EF
• A ratio of peak segmental longitudinal strain difference to peak systolic GLS >1.0 has 77.3% sensitivity and 79.2% specificity for CAD 6

Pulmonary Hypertension

• Decreased peak atrial longitudinal strain (PALS <12.5%) is associated with persistent pulmonary hypertension
• Requires careful monitoring due to association with increased heart failure hospitalization and mortality 7

3. Follow-up Recommendations

• Mild Abnormality: Follow-up echocardiography in 6-12 months
• Moderate Abnormality: Follow-up in 3-6 months with repeat GLS measurement
• Severe Abnormality: Follow-up in 1-3 months with comprehensive cardiac evaluation 1

Technical Considerations and Limitations

When interpreting GLS measurements, consider:

• Vendor Variability: Ensure serial measurements use the same vendor's equipment
• Image Quality: Poor image quality significantly affects accuracy
• Loading Conditions: GLS may be affected by loading conditions and heart rate
• Regional vs. Global: Regional strain measurements are less reliable than global measurements 1

Pitfalls to Avoid

• Overreliance on EF: Don't dismiss cardiac dysfunction concerns when EF is normal but GLS is abnormal
• Vendor Inconsistency: Avoid comparing GLS values measured on different vendor platforms
• Isolated Interpretation: Don't interpret GLS in isolation; consider clinical context and other cardiac parameters
• Delayed Follow-up: Abnormal GLS values warrant timely follow-up, especially in high-risk patients 1, 2

By systematically evaluating and managing patients with abnormal GLS values, clinicians can identify subclinical cardiac dysfunction earlier, potentially improving outcomes through earlier intervention.