P-wave morphology can help determine the location of the arrhythmia focus. true or false?

• A. True
• B. False
• C. Not informative
• D. Only during atrial fibrillation

Answer: (A)

P-wave morphology reflects the direction of atrial activation. A focal atrial tachycardia starts at a specific site, and the depolarization wave spreads through the atria in a characteristic pattern. That pattern shows up as distinct P-wave shapes and polarities across the ECG leads, giving clues about where in the atria the focus is located. For example, a focus in different atrial regions tends to produce different P-wave directions in the limb leads and precordial leads, so examining the P-wave appearance helps guide localization during EP evaluation.

Keep in mind that this isn’t perfect: atrial size, conduction pathways, and lead placement can modify P-wave appearance, and during atrial fibrillation there aren’t discrete P waves to analyze, so morphology isn’t informative in that setting. But for regular atrial tachycardias, P-wave morphology can point you toward the likely region of origin and help plan mapping and ablation.