I love this EKG! The rhythm is basically 2° AV block, Type II…but with a twist! The P waves are regular with multiple dropped beats. The conducted beats have a constant PR interval, except for the first PR interval of each group that is actually a bit longer. Maybe this is a “reverse Wenckebach”?!

No, actually, the initial slightly longer PR interval is likely non-conducting – the first QRS of each group is probably a junctional escape beat. Notice that the first QRS of both groups is the exact same distance from the preceding QRS, and at a rate consistent with an escape beat. Notice also that the purported escape beats are ever so slightly different in morphology compared to the normally conducted beats.