What is Global Longitudinal Strain (GLS)?
Global Longitudinal Strain (GLS) is an echocardiographic technique used to measure the movement and deformation of the heart's left ventricle muscle. It provides a more nuanced and sensitive assessment of myocardial mechanics than the traditional Left Ventricular Ejection Fraction (LVEF). Unlike LVEF, which measures the overall pumping capacity, GLS focuses on the heart muscle's ability to contract and relax in a longitudinal (lengthwise) direction. This makes it particularly useful for detecting early or subclinical cardiac dysfunction, even when the LVEF still appears normal.
It is important to differentiate this from other meanings of the acronym GLS, such as General Logistics Systems (a delivery service) or the GLS1 enzyme, which is the focus of anti-aging research related to senescent cells. In the context of healthy aging and senior care, the focus is on the cardiac measurement.
The Age-Related Decline in GLS
Multiple studies confirm that GLS decreases with advancing age. The heart muscle naturally undergoes changes over time, becoming stiffer and less elastic. This leads to reduced longitudinal function, which is precisely what a lower (less negative) GLS measurement indicates. The decline becomes more pronounced after the age of 50 or 60, with researchers noting significant reductions in individuals in their sixth decade and older.
Sex-Specific Differences in GLS Changes
One of the most significant findings in GLS research is the difference in how age affects this metric between sexes.
Findings in Women
For women, studies have consistently shown a more prominent, significant age-related decline in GLS. This decline is particularly notable in women aged 60 and older. Proposed explanations for this trend include hormonal factors, such as the drop in estrogen levels after menopause, which may diminish cardioprotective effects. Changes in the heart muscle tissue itself are also more pronounced in women.
Findings in Men
In contrast, research on male participants has shown a less significant correlation between age and GLS decline. Some studies found no significant age dependency in men, while others observed a decline but to a lesser degree than in women. This difference highlights the importance of sex-specific reference ranges when interpreting GLS measurements in older adults.
Why Are Changes in GLS Important for Healthy Aging?
The changes in GLS with age are not merely a curiosity; they have profound clinical implications, especially for those with preserved LVEF.
A Sensitive Marker of Risk
Reduced GLS serves as an early marker of subclinical cardiac dysfunction, identifying individuals at a higher risk of future cardiovascular problems, including heart failure and mortality. This is crucial for early intervention and preventive care.
Prognostic Value Beyond LVEF
GLS has been shown to offer incremental prognostic value over traditional risk scores and LVEF, meaning it can help predict long-term outcomes more accurately. Identifying a poor GLS in a patient with an otherwise normal LVEF can prompt closer monitoring and proactive management.
Comparing GLS and LVEF
| Feature | Global Longitudinal Strain (GLS) | Left Ventricular Ejection Fraction (LVEF) |
|---|---|---|
| Measurement Type | Reflects the active, longitudinal shortening and lengthening of the heart muscle. | Measures the percentage of blood pumped out of the left ventricle with each beat. |
| Sensitivity | Highly sensitive to subtle changes in heart muscle function. Can detect dysfunction even when LVEF is normal. | Less sensitive to early changes. Often remains in the normal range until damage is more advanced. |
| Age Trend | Shows a clear, progressive decline with age, particularly in women. | Can remain normal despite age-related changes in heart muscle mechanics. |
| Clinical Usefulness | Excellent for identifying early or subclinical heart dysfunction and risk stratification. | Standard and widely used, but may miss subtle issues. |
Managing Age-Related Changes in GLS
While some age-related decline is inevitable, several strategies can help maintain optimal heart function and mitigate adverse changes in GLS.
Lifestyle Modifications
- Diet: A heart-healthy diet, such as the Mediterranean or DASH diet, is beneficial. Studies show that factors like cholesterol and hypertension, both impacted by diet, are associated with lower GLS.
- Exercise: Regular physical activity, including both aerobic and resistance training, is crucial. It helps maintain cardiovascular fitness and overall heart health.
- Weight Management: Maintaining a healthy body weight is important, as higher BMI is linked to lower GLS.
- Monitor Vitals: Regularly monitoring blood pressure and heart rate can help in early detection of issues.
Medical Monitoring and Management
- Regular Check-ups: Consistent medical evaluation allows for early detection of risk factors like hypertension and diabetes, which are associated with reduced GLS.
- GLS Testing: For older individuals, particularly women, adding a GLS measurement to routine echocardiograms can provide a more complete picture of cardiac health. This is especially relevant if other risk factors are present.
- Address Underlying Conditions: Effectively managing chronic conditions like hypertension and diabetes is critical to mitigating their impact on heart function.
For more information on cardiovascular research, including the latest findings on GLS and aging, consult reputable sources like the American Heart Association Journals.
Conclusion
In summary, the question of "how does GLS change with age?" is answered by a clear trend of gradual decline. This change is more significant in older women and serves as a valuable, sensitive indicator of subclinical heart dysfunction, even when LVEF is normal. By embracing heart-healthy lifestyle choices and regular medical monitoring that includes GLS assessment, seniors can better understand their cardiovascular risk and take proactive steps toward healthy aging.
