What identifies a heart rate greater than 100 beats per minute with a P wave before the QRS complex?

A heart rate greater than 100 beats per minute, accompanied by a P wave before the QRS complex, indicates sinus tachycardia. In this heart rhythm, the normal sinus node serves as the pacemaker, leading to an increase in heart rate while maintaining the characteristic P wave. The presence of the P wave signifies that the electrical impulses are still originating from the atria, which is essential in distinguishing sinus tachycardia from other tachyarrhythmias, where P waves may be absent or abnormal.

In sinus tachycardia, the heart rate can rise in response to various physiological or pathological stimuli, such as stress, exercise, or fever. It reflects an appropriate physiological response in many situations, as the body requires more oxygenated blood during increased activity.

The other options do not meet the criteria described in this question. Sinus bradycardia involves a heart rate below 60 beats per minute. Atrial flutter may present with a rapid rate but often has a characteristic "sawtooth" pattern of the atrial activity instead of distinct P waves. Premature contractions can occur, but their defining characteristic is an early heartbeat that disrupts the normal rhythm rather than an elevated heart rate along with consistent P waves.