An irregularly irregular rhythm with multiple P-wave morphologies and a rate over 100 bpm is best diagnosed as which rhythm?

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Recognizing multifocal atrial tachycardia comes from identifying an irregular rhythm with several different P-wave shapes, each before a QRS complex, indicating atrial impulses arise from multiple foci rather than one pacemaker. The rate is over 100 bpm, and the irregularity is due to the shifting dominant atrial focus. This contrasts with sinus tachycardia, which has a fast but regular rhythm and a single, normal P-wave morphology. It also differs from sinus arrhythmia, which is usually regular with small, respiration-related variations and normal P waves. Atrial fibrillation also has irregular rhythm, but there are no distinct P waves at all—just an irregular baseline with fibrillatory activity. So the combination of an irregular rhythm, rapid rate, and multiple P-wave morphologies points to multifocal atrial tachycardia.