The atrial premature beat labeled Pā (arrow) depolarizes the sinus node and resets it. For this reason, the duration of the Pā-P interval will equal the sum of the time required for the premature atrial impulse to travel to the sinus node and depolarize it plus the normal sinus P-P interval. If the premature focus is in close proximity to the sinus node, the time required for the impulse to travel to the sinus node will be short and the interval between the premature P wave and the following sinus node discharge, the Pā-P interval, will approximate the sinus P-P interval. The longer the time for the premature impulse to travel to reset the sinus node, the longer the Pā-P interval. In this example, the sinus (PP) interval is 0.72 seconds, the Pā-P interval is 0.88 seconds and the interval between the QRS complexes that precede and follow the premature complex measures 1.24 seconds. This is less than twice the sinus interval of 1.42 seconds, and indicates the absence of a fully compensatory pause.