What is the significance of the time gap in the passage of the action potential from the sino-atrial node to the ventricle?

(N/A) The time gap allows the ventricles to remain relaxed while the action potential travels from the sino-atrial $(SA)$ node to the ventricles. This delay ensures that the atria complete their contraction (atrial systole) and empty their blood into the ventricles before the ventricles begin to contract. This maximizes ventricular filling,thereby increasing cardiac output.