Methods and systems are provided for detecting arrhythmias in cardiac activity is provided. The method and systems are under control of one or more processors configured with specific executable instructions. The method and systems obtain a far field cardiac activity (CA) signal that includes a series of beats, the CA signal including paced events. The method and systems identify the paced events in the CA signals. The method and systems determine a score based on an amount of paced events and adjust at least one parameter of an atrial fibrillation (AF) detection process based on the score.