The heart is a muscular pump whose function is measured by its ability to push oxygenated blood efficiently throughout the body. As the human body ages, the cardiovascular system undergoes senescence. A common question is whether the heart’s pumping efficiency declines with age, particularly concerning a measurement known as the Ejection Fraction (EF). Understanding EF requires distinguishing between the heart’s pumping action and its ability to relax, as aging affects these two functions differently.
What Ejection Fraction Measures
The Ejection Fraction (EF) quantifies the efficiency of the heart’s primary pumping chamber, the left ventricle. It is expressed as a percentage, representing the fraction of blood ejected from the ventricle with each contraction. For example, a Left Ventricular Ejection Fraction (LVEF) of 60% means 60% of the blood in the left ventricle is pushed out during the subsequent beat.
EF measures the heart’s systolic function, which is its muscular squeezing power. Doctors typically use non-invasive imaging tests to determine the EF, with the echocardiogram being the most widely used method. Other techniques, such as Cardiac Magnetic Resonance Imaging (MRI) or nuclear stress tests, can also provide this measurement.
Structural Changes in the Heart Muscle Due to Aging
The physiological changes occurring with age provide the context for any change in EF. A consistent finding is a modest thickening of the left ventricular wall, known as hypertrophy. This increase in muscle size is primarily due to an increase in the size of individual heart muscle cells, or cardiomyocytes.
The heart tissue also becomes less compliant due to cardiac fibrosis, which is the accumulation of extracellular matrix proteins like collagen. This remodeling increases the stiffness of the ventricle, making it harder for the chamber to fully relax and stretch to accommodate blood. This stiffness primarily impacts the heart’s diastolic function—its ability to relax and fill properly between beats.
The large arteries stiffen with age due to the loss of elastic tissue and the deposition of collagen and calcium. This arterial stiffening increases the resistance the heart must pump against, known as afterload. This increased afterload further contributes to the left ventricular wall thickening, impacting the heart’s reserve capacity even if the resting EF remains stable.
Ejection Fraction and Healthy Aging Populations
In healthy individuals free of cardiovascular disease, the Left Ventricular Ejection Fraction (LVEF) measured at rest generally does not decrease with age. Studies show that resting EF remains within the normal range, indicating that the heart’s systolic pumping action at rest is preserved. This preservation is largely due to the compensatory effect of the modest thickening of the heart wall.
A significant difference emerges when the heart is placed under stress, such as during vigorous exercise. The heart’s ability to increase its EF—a measure of cardiac reserve—is notably diminished in older adults. For example, LVEF was less than 60% during exercise in nearly half of healthy subjects over age 60 in one study, compared to a small percentage of younger subjects.
This blunted response means the older heart cannot increase its systolic function as forcefully as a younger heart to meet peak demand. The aging heart compensates by relying more on the Frank-Starling mechanism, which involves increasing the total volume of blood in the ventricle before contraction. This physiological shift illustrates a decline in the dynamic reserve capacity of the heart with advancing age.
Monitoring Ejection Fraction and Clinical Significance
Ejection Fraction is a foundational measurement in cardiovascular medicine, providing insight into the heart’s overall functional state. LVEF is typically considered normal when it falls between 55% and 70%. A measurement between 41% and 49% is considered mildly reduced and may suggest early heart damage.
A reading of 40% or lower generally indicates heart failure with reduced ejection fraction (HFrEF), meaning the heart muscle is not contracting effectively. Conversely, many older adults develop heart failure with preserved ejection fraction (HFpEF), where the EF is normal, but the issue is the heart’s stiffness and inability to fill properly. Therefore, a normal EF alone does not guarantee a fully healthy heart, especially given age-related diastolic impairment.
Clinicians use EF to stage heart failure, guide treatment decisions, and monitor therapy effectiveness. While age-related changes are inevitable, maintaining a physically active lifestyle can help mitigate the decline in ventricular compliance and preserve the heart’s ability to respond to stress.