Why is EF alone an imperfect measure of systolic function, and how does GLS complement it?

Why is EF alone an imperfect measure of systolic function, and how does GLS complement it?

• A. EF is load-independent and GLS is irrelevant.
• B. EF is load-dependent and may misestimate function; GLS detects subclinical dysfunction earlier.
• C. GLS replaces EF in all assessments.
• D. EF is not used in modern practice; GLS is the only measure.

Answer: (B)

EF measures how much blood the left ventricle ejects with each beat, but it is heavily influenced by loading conditions like preload and afterload. Because these loading factors can change day to day, EF can look normal even when myocardial contractility is impaired, or appear reduced when the heart is actually compensating in other ways. EF also averages the function of the entire ventricle and can miss regional or subtle dysfunction, especially when disease affects primarily the inner (subendocardial) fibers. Global longitudinal strain assesses how much the heart muscle shortens along the long axis, focusing on those subendocardial fibers that are commonly affected early in disease. Because strain detects this deformation more sensitively, GLS often becomes abnormal before EF deteriorates, signaling subclinical systolic dysfunction. In practice, using both measures gives a fuller view: EF tells you about overall pumping performance, while GLS reveals early or regional dysfunction and helps with prognosis and monitoring, even when EF seems preserved.

EF measures how much blood the left ventricle ejects with each beat, but it is heavily influenced by loading conditions like preload and afterload. Because these loading factors can change day to day, EF can look normal even when myocardial contractility is impaired, or appear reduced when the heart is actually compensating in other ways. EF also averages the function of the entire ventricle and can miss regional or subtle dysfunction, especially when disease affects primarily the inner (subendocardial) fibers. Global longitudinal strain assesses how much the heart muscle shortens along the long axis, focusing on those subendocardial fibers that are commonly affected early in disease. Because strain detects this deformation more sensitively, GLS often becomes abnormal before EF deteriorates, signaling subclinical systolic dysfunction. In practice, using both measures gives a fuller view: EF tells you about overall pumping performance, while GLS reveals early or regional dysfunction and helps with prognosis and monitoring, even when EF seems preserved.