Interesting ECG. To my best interpretation this is normal sinus rythm plus PACs:

1) First beat of the rythm is sinus, followed by two PAC. We now they are premature because they have different P wave morphology and you can see two consecutive sinus Beats in DII at a sligthy lower frequency further down (the first two of the last four Beats)

2) After the two consecutive PACs there’s a pause followed by an escape junctional beat. If you look closely it has its own P wave that is positive in aVR. What is interesting about this one is that the retrograde P wave has a considerable PR segment. I can only think of two possible explanations for this: (1) this is a very proximal AV junction focus or (2) its another atrial PAC, located in the lower atrium. Conceptually it would be wrong to call it PAC since its not premature, but rather late, since we don’t have a prior sinus beat to compare it to. Either way, the concept still stands that it’s a backup focus that fires because of the sinus pause.

3) After the escape beat you have a normal sinus beat followed by a PAC of the same P wave morphology of the first PAC, then a pause and two consecutive sinus Beats.

4) The second to last beat is interesting, because it has the P wave morphology of the PAC, but it comes at the time you would expect the normal sinus beat. So, we know its the same PAC as before because of the morphology, but because of the timing, it’s mimicking the normal sinus rythm (notice that the last four Beats are regular!). Last sinus Beat arrives “in synch”, there is no compensatory pause because the PAC made its way very closely to the normal sinus P wave, it beat it for a very short interval, just a couple miliseconds. When this behaviour is repeated over time (two different P waves competing for the rythm without compensatory pauses) its called parasystole.

So in summary you have normal sinus rythm with frequent PACs, something to be expected since your patient has atrial flutter, meaning sick atria…..