Which statement best describes the ECG comparison between atrial flutter and atrial fibrillation?

• A. Sawtooth flutter waves with regular atrial activity (around 250–350 bpm) in flutter; AF is irregularly irregular with no stable P waves.
• B. Flutter shows delta waves on ECG.
• C. AF has sawtooth waves with regular rhythm.
• D. Flutter shows ST-segment elevation.

Answer: (A)

The main idea is that atrial flutter and atrial fibrillation show two very different patterns of atrial activity on ECG. Atrial flutter is an organized, rapid atrial rhythm that produces sawtooth flutter waves. The atrial rate is typically around 250–350 beats per minute, and the atrial activity is regular, with the ventricular rhythm reflecting a consistent AV conduction ratio (though the exact rate of the ventricles can vary if the conduction ratio changes).

Atrial fibrillation, in contrast, is a chaotic, disorganized atrial activity. There are no discrete P waves; instead you see a fine to coarse fibrillatory baseline. The ventricular response is irregularly irregular because AV nodal conduction filters the many chaotic atrial impulses in an unpredictable way.

So the statement you’re looking for correctly notes the hallmark differences: flutter shows sawtooth flutter waves with regular atrial activity around 250–350 bpm; atrial fibrillation shows an irregularly irregular rhythm with no stable P waves. The other options don’t fit because they refer to features not characteristic of flutter or AF, such as delta waves indicating pre-excitation or ST-segment elevation, which isn’t a defining feature of these rhythms.