Is a global longitudinal strain (GLS) of -18 considered normal in a patient with no symptoms or underlying medical conditions?

Is Global Longitudinal Strain of -18% Normal?

A GLS of -18% falls at the lower boundary of normal and represents borderline left ventricular systolic function that warrants close monitoring, as values between -16% to -18% are considered borderline according to European Society of Cardiology guidelines. 1

Understanding the Measurement

• Normal GLS ranges from -18% to -22%, with -18% representing the lower limit of normal 1, 2
• Values between -16% to -18% are classified as borderline, while anything above -16% (less negative) is abnormal 1, 2
• The European Heart Journal guidelines specifically state that values < -16% indicate mild depression of GLS, positioning your -18% value right at the threshold 3

Clinical Significance

• GLS is more sensitive than ejection fraction for detecting early myocardial dysfunction, often identifying abnormalities months before EF declines 1, 4
• A GLS of -18% in an asymptomatic patient with no cardiac risk factors and normal ejection fraction may represent normal variation, particularly in certain populations like athletes 4
• However, this value signals that the longitudinal subendocardial fibers are functioning at the minimal acceptable level and any further decline would be pathological 1

Critical Considerations

Vendor Variability

• Significant vendor variability exists between different ultrasound machines and software versions, making absolute values difficult to interpret in isolation 3, 1, 4
• The writing committee consensus indicates that differences among vendors are still too large to recommend universal normal values, though a peak GLS around -20% is expected in healthy individuals 3

What This Means for You

• If you are asymptomatic with no cardiac risk factors and normal ejection fraction, a single GLS of -18% does not necessarily indicate disease 4
• If you have cardiac risk factors (hypertension, diabetes, prior cardiotoxic therapy), this borderline value represents early subclinical dysfunction requiring intervention 1

Recommended Actions

Immediate Steps

• Confirm the measurement by repeating echocardiography with the same equipment vendor within 2-3 weeks to account for measurement variability 1, 4
• Document your absolute GLS value and compare to the normal range of -18% to -22% 1

Ongoing Monitoring

• Do not dismiss this borderline value as completely normal—it represents early dysfunction requiring close monitoring 1
• Implement serial GLS monitoring every 3-6 months to detect progression, as worsening GLS over time indicates pathological deterioration 4
• Reduction in GLS over time is more concerning than a single abnormal value and mandates therapeutic intervention 1

Risk Factor Management

• Address modifiable risk factors: hypertension control, diabetes management, smoking cessation, alcohol abstinence 1
• Initiate or optimize guideline-directed medical therapy if heart failure risk factors are present, such as ACE inhibitors/ARBs and beta-blockers, even with preserved ejection fraction 1, 4

Important Caveats

• GLS values are not applicable if you are currently receiving inotropic agents or mechanical circulatory support, as these interventions alter the measurement 3, 1, 4
• Clinical context matters significantly—recent viral illness, athletic training status, or other conditions can explain borderline GLS values 4
• Blood pressure affects GLS measurements, so systolic blood pressure should be considered in interpretation 5