Which pathophysiology best describes a left ventricular systolic dysfunction with an ejection fraction of 33%?

Which pathophysiology best describes a left ventricular systolic dysfunction with an ejection fraction of 33%?

• A. Diastolic dysfunction due to stiff ventricle
• B. Systolic dysfunction with decreased contractility
• C. Arrhythmia causing heart failure
• D. Valvular stenosis causing heart failure

Answer: (B)

A reduced ejection fraction of 33% signals a pumping problem in the left ventricle, i.e., systolic dysfunction. Ejection fraction is the percentage of blood in the ventricle that is ejected with each heartbeat, and normal is about 55%–70%. When contractility is weakened, the ventricle can’t eject as much blood with each beat, so the stroke volume falls and more blood remains at the end of systole. This leads to a lower EF and often to a dilated, less efficient ventricle—classic left ventricular systolic dysfunction or heart failure with reduced ejection fraction. In contrast, diastolic dysfunction involves a stiff or noncompliant ventricle that doesn’t fill properly, but the systolic contractile function is typically preserved, so the ejection fraction remains normal or near normal. Arrhythmias can contribute to heart failure but the hallmark measurement here points to impaired systolic contraction rather than an arrhythmia-driven problem. Valvular stenosis causes heart failure through pressure overload from the narrowed valve; it can eventually affect systolic function, but the defining description for an EF as low as 33% is decreased contractility leading to systolic dysfunction.

A reduced ejection fraction of 33% signals a pumping problem in the left ventricle, i.e., systolic dysfunction. Ejection fraction is the percentage of blood in the ventricle that is ejected with each heartbeat, and normal is about 55%–70%. When contractility is weakened, the ventricle can’t eject as much blood with each beat, so the stroke volume falls and more blood remains at the end of systole. This leads to a lower EF and often to a dilated, less efficient ventricle—classic left ventricular systolic dysfunction or heart failure with reduced ejection fraction.

In contrast, diastolic dysfunction involves a stiff or noncompliant ventricle that doesn’t fill properly, but the systolic contractile function is typically preserved, so the ejection fraction remains normal or near normal. Arrhythmias can contribute to heart failure but the hallmark measurement here points to impaired systolic contraction rather than an arrhythmia-driven problem. Valvular stenosis causes heart failure through pressure overload from the narrowed valve; it can eventually affect systolic function, but the defining description for an EF as low as 33% is decreased contractility leading to systolic dysfunction.