Atrial Flutter: The Daily PANCE Blueprint
A 68-year-old man with COPD presents with 2 days of palpitations and mild exertional dyspnea. His blood pressure is 128/78 mm Hg, and his pulse is a regular 150/min. He is alert, and his lungs have scattered expiratory wheezes. The ECG shows a regular narrow-complex tachycardia at 150/min with "sawtooth" waves best seen in leads II, III, and aVF. Which of the following is the most likely diagnosis?
A. Sinus tachycardia
B. Atrioventricular nodal reentrant tachycardia
C. Multifocal atrial tachycardia
D. Atrial flutter
E. Atrial fibrillation
Answer and topic summary
The answer is D. Atrial flutter
Atrial flutter is a macroreentrant atrial rhythm, most often a circuit around the tricuspid annulus through the cavotricuspid isthmus. The atria fire at about 300/min, and with the usual 2:1 AV block the ventricular rate sits right at 150/min. That regularity, plus “sawtooth” flutter waves in the inferior leads (II, III, aVF), makes the diagnosis. A board pearl: any regular narrow-complex rhythm at exactly 150 is flutter until proven otherwise; adenosine can slow AV conduction and unmask the flutter waves. Atrial fibrillation is irregularly irregular with no organized atrial activity. Multifocal atrial tachycardia is the classic COPD trap, but it is irregular, with at least three different P-wave shapes. AV nodal reentrant tachycardia has no visible flutter waves. Management mirrors atrial fibrillation: rate control, anticoagulation by CHA2DS2-VASc score, cardioversion if unstable, and catheter ablation of the cavotricuspid isthmus as definitive therapy.
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