What does a global longitudinal strain (GLS) of -14% in echocardiography indicate?

Interpretation of Global Longitudinal Strain (GLS) of -14% on Echocardiography

A global longitudinal strain (GLS) value of -14% indicates moderate myocardial dysfunction that requires further clinical evaluation and monitoring, even if the ejection fraction appears preserved.

Understanding GLS Values and Clinical Significance

GLS is a measure of the active shortening of the left ventricle in the longitudinal direction, assessed with speckle-tracking echocardiography. It provides a more sensitive assessment of myocardial function than traditional ejection fraction measurements.

According to established reference ranges:

• Normal GLS: > -18% (more negative)
• Borderline GLS: -16% to -18%
• Abnormal GLS: ≤ -16% (less negative) 1

With a GLS of -14%, the patient falls into the abnormal category, indicating:

• Moderate impairment of left ventricular systolic function
• Subclinical myocardial dysfunction that may not be detected by ejection fraction alone
• Potential increased risk for adverse cardiovascular outcomes

Clinical Implications

Prognostic Significance

• A GLS of -14% is associated with increased risk of:
  • Heart failure hospitalizations
  • Ventricular arrhythmias
  • Cardiovascular mortality 1, 2
  • All-cause mortality (particularly in ischemic cardiomyopathy patients) 2

Potential Underlying Conditions

A GLS of -14% may indicate:

• Early stage cardiomyopathy
• Subclinical coronary artery disease
• Early cardiotoxicity from chemotherapy agents
• Heart failure with preserved ejection fraction (HFpEF)
• Valvular heart disease 1

Recommended Follow-up Actions

1. Comprehensive cardiac evaluation:

   • Assessment of symptoms (dyspnea, chest pain, palpitations)
   • Review of cardiovascular risk factors
   • Evaluation of biomarkers (troponin, BNP/NT-proBNP)

2. Additional cardiac imaging as appropriate:

   • Stress echocardiography or cardiac MRI to assess for ischemia
   • Serial GLS measurements to monitor for progression

3. Investigation of potential causes:

   • Coronary artery disease assessment
   • Evaluation for cardiomyopathies
   • Review of medication history (particularly cardiotoxic agents)
   • Screening for systemic diseases affecting the heart

Special Considerations

In Chemotherapy Patients

• A ≥11% relative reduction in GLS predicts subsequent cardiotoxicity
• A 10-15% early reduction in GLS during therapy is the most useful parameter for predicting cardiotoxicity 3

In Heart Transplant Patients

• Reduced GLS values may represent normal values in this population or subtle alterations leading to myocardial dysfunction
• A reduction of GLS over time must be interpreted as pathological 3

Technical Considerations

• Ensure measurements are performed using the same vendor's equipment for serial assessments due to inter-vendor variability
• Image quality significantly affects accuracy of GLS measurements 1
• GLS may be affected by loading conditions and heart rate 1

Conclusion

A GLS of -14% represents moderate myocardial dysfunction that warrants clinical attention and further evaluation, even if ejection fraction is preserved. This finding is more sensitive than ejection fraction for detecting early myocardial damage and has significant prognostic implications for cardiovascular outcomes.