What happens to atria remain in diastole?

When the atria remain in diastole, they are in a relaxed state, allowing them to fill with blood from the veins (the superior and inferior vena cavae for the right atrium and the pulmonary veins for the left atrium). This phase is crucial for proper heart function, as it ensures that enough blood is collected to be pumped into the ventricles during the subsequent contraction (systole). If the atria remain in diastole for too long or fail to contract properly, it can lead to inadequate blood flow and potential complications like heart failure or arrhythmias.