What percentage can atrial fibrillation reduce cardiac output by due to the loss of atrial kick?

In atrial fibrillation, the loss of coordinated atrial contraction, known as the atrial kick, can significantly impact cardiac output. The atrial kick contributes approximately 20% to 30% of the total stroke volume in a normal heart rhythm. When a person experiences atrial fibrillation, this contribution is compromised, leading to a notable reduction in cardiac output.

The correct answer reflects the understanding that in cases of atrial fibrillation, cardiac output may decrease on average by about 30%, specifically due to the absence of the effective atrial kick. This decline is particularly significant in conditions where the heart relies on the atrial contraction to fill the ventricles effectively, such as in patients with reduced ventricular function or in those with heart failure. Recognizing this loss is essential in both assessing patients and managing their care effectively. Thus, the choice indicating a 30% reduction accurately represents the impact of atrial fibrillation on cardiac output in clinical practice.