A premature P wave in the EKG is referred to as a?

A premature P wave in the electrocardiogram (EKG) is indeed referred to as a PAC, which stands for premature atrial contraction. PACs occur when an ectopic focus in the atrium fires before the next expected sinus node impulse, resulting in an early P wave that is typically followed by a QRS complex. This type of contraction is significant because it indicates that there is a point of irritability in the atrial tissue, which can be triggered by various factors such as stress, caffeine, or electrolyte imbalances.

The other options relate to different cardiac phenomena. PSVT, or paroxysmal supraventricular tachycardia, describes a rapid heart rate originating above the ventricles, often related to reentrant circuits and not just an early atrial contraction. A ventricular escape beat occurs when the heart's normal pacemaker fails or slows down, causing the ventricles to take over their pacing, which is different from a premature atrial event. Sinus arrhythmia refers to a variation in heart rhythm that is typically benign and linked to respiration but does not involve early atrial contractions.