not sure what the discussant means by "mobitz 1"; mobitz 1 AV block does not appear to be present, perhaps he/she meant mobitz 1 SA block. I do not know the diagnosis (only a student) but can tell there is a grossly abnormal p wave axis indicating an ectopic atrial rhythm and sinus/atrial pauses between every 3 beats. if I had to guess a diagnosis it would be ectopic atrial rhthm and SA node wenkebach. of course in this case "sinus node exit block" doesnt really apply because the sinus node isnt doing anything; the pacemaker appears to be ectopic atrial tissue in the lower left atrium. so it would be something like "ectopic atrial rhythm with possible intra atrial conduction disease in a wenkebach pattern. please respond, I want to know if my interpretation of this fascinating ecg is correct. from josh