A 38 year-old-male patient with syncope and familial PRKAG2 cardiomyopathy due to R302Q mutation was admitted in 2004 with recurrent syncope and advanced AV block for a dual chamber pacemaker implantation (Panel A). In 2017, the electrocardiogram during reprogrammed DDD pacing set at 30 beats, showed sinus bradycardia and split P waves (arrows) (Panel B), with prolonged interatrial conduction time, without split intracavitary atrial electrograms (Panel C). Longitudinal tissue Doppler biatrial strain imaging (Panels D and E) revealed the right atrial contraction curve to occur during the first P wave, while left atrial contraction curve occurred just after the second P wave, with the deformation curve earlier and greater in the lateral wall compared to the interatrial septum. The...