Reduced Global Longitudinal Strain and Subclinical Cardiomyopathy

Introduction to Subclinical Cardiomyopathy

The European Society of Cardiology recommends that reduced global longitudinal strain (GLS) consistent with subclinical cardiomyopathy indicates early myocardial dysfunction that precedes overt heart failure and is detectable before ejection fraction declines, representing a critical window for intervention to prevent progression to symptomatic disease 1, 2

GLS measures the maximal shortening of left ventricular myocardium during systole, expressed as a negative percentage, with values closer to zero (less negative) representing worse function 3
Normal GLS ranges from -18% to -22%, with values between -16% to -18% considered borderline, and anything above -16% (less negative) classified as abnormal 3
GLS is more sensitive than ejection fraction for detecting early myocardial dysfunction, often identifying abnormalities months before EF declines 3

Strain measurements are abnormal in many clinical settings with preserved LV EF, making this a marker of subclinical dysfunction 4, 5

Repeat echocardiography with the same equipment vendor within 2-3 weeks, as significant vendor variability exists between different ultrasound machines and software versions 3
Measure left ventricular ejection fraction using 3D echocardiography when available for superior reproducibility 6
Document the absolute GLS value and compare to normal range (normal: -18% to -22%) 3
Assess diastolic function using four key variables: septal e′ velocity, lateral e′ velocity, average E/e′ ratio, and LA maximum volume index 1, 2
Evaluate right ventricular function to exclude biventricular involvement, as this has prognostic implications 6

Cardiac MRI is indicated when diagnostic uncertainty exists regarding etiology of reduced GLS, particularly for suspected infiltrative disease where MRI provides superior tissue characterization 6
MRI with late gadolinium enhancement can differentiate ischemic from non-ischemic cardiomyopathy and identify specific patterns of infiltration 6
Screen for reversible causes: thyroid function, iron studies, nutritional deficiencies (thiamine, selenium) 6

Initiate or optimize guideline-directed medical therapy if heart failure risk factors are present: ACE inhibitors/ARBs and beta-blockers should be started even with preserved ejection fraction when GLS is reduced 3
Address modifiable risk factors: hypertension control, diabetes management, smoking cessation, alcohol abstinence 8
Discontinue cardiotoxic medications if identified as the cause 6

Do not dismiss borderline GLS values (between -16% to -18%) as normal—these represent early dysfunction requiring close monitoring 3
GLS values are not applicable to patients currently receiving inotropic agents or mechanical circulatory support, as these interventions alter the measurement 3
Diastolic abnormalities often precede systolic dysfunction and cause symptoms despite normal EF—always perform comprehensive diastolic assessment 6
Reduction in GLS over time is more concerning than a single abnormal value and mandates therapeutic intervention 6