Which finding is NOT typical of Multifocal Atrial Tachycardia?

Which finding is NOT typical of Multifocal Atrial Tachycardia?

• A. HR > 100
• B. Three or more P-wave morphologies
• C. PR interval variation
• D. Delta wave

Answer: (D)

MAT is defined by an irregularly irregular rhythm with multiple atrial pacemaker sites. The clocking is variable because different foci fire at different times, so you see at least three distinct P-wave morphologies on the ECG. With these multiple atrial sources, the PR interval can vary from beat to beat, since the initiating P waves come from different atrial locations and may conduct differently to the ventricles. Delta waves, on the other hand, come from pre-excitation through an accessory pathway, as in Wolff-Parkinson-White syndrome. They produce a slurred upstroke at the start of the QRS and a shortened PR interval. This pre-excitation pattern is not a feature of Multifocal Atrial Tachycardia, which is why a delta wave is not typical for MAT.

MAT is defined by an irregularly irregular rhythm with multiple atrial pacemaker sites. The clocking is variable because different foci fire at different times, so you see at least three distinct P-wave morphologies on the ECG. With these multiple atrial sources, the PR interval can vary from beat to beat, since the initiating P waves come from different atrial locations and may conduct differently to the ventricles.

Delta waves, on the other hand, come from pre-excitation through an accessory pathway, as in Wolff-Parkinson-White syndrome. They produce a slurred upstroke at the start of the QRS and a shortened PR interval. This pre-excitation pattern is not a feature of Multifocal Atrial Tachycardia, which is why a delta wave is not typical for MAT.