The evident “Group Beating” could be simply Atrial Bigemini with lengthy post-extrasystolic pause, but that’s not the case here.
The most likely rhythm here is 3:2 Type II Sinoatrial Exit Block which results in missing P wave.
Note that this is occurring during an Acute Infero Postero Lateral Myocardial Infraction.
Recall that Sino-Atrial Node artery is usually a brach of the Right Coronary Artery, and with its occlusion there may be significant problems with sinus impulse formation.
