There are four main characteristics of PACs ... from the normal sinus P wave morphology. When every other QRS complex is a premature atrial contraction, then the rhythm is referred to as ...

Thus, it must "skip a beat" and it will resume exactly 2 P-to-P intervals after the last normal sinus beat. When every other QRS complex is a PAC, then the rhythm is referred to as "atrial bigeminy".

To maintain sinus rhythms ... likely to respond to PAC-suppressing pacing algorithms. Patients with low PAC activity before AF onset, on the other hand, have a prolonged arrhythmia episode ...