A 68-year-old man with severe COPD exacerbation presents with an irregular tachycardia at 130 bpm. ECG shows at least three distinct P wave morphologies with variable PP, PR, and RR intervals. Which statement is correct?
- A This rhythm responds best to immediate synchronized cardioversion
- B Catheter ablation at the cavotricuspid isthmus is curative
- C Verapamil may control the rate, but correcting hypoxia and treating the underlying lung disease is essential ✓
- D Digoxin is the drug of choice because it converts the rhythm to sinus
Correct answer: C. Verapamil may control the rate, but correcting hypoxia and treating the underlying lung disease is essential
Explanation
Multifocal atrial tachycardia shows three or more P wave morphologies with irregular intervals and occurs almost exclusively in elderly patients with decompensated COPD. Management centers on oxygenation, bronchodilation, and correction of electrolyte abnormalities; verapamil or diltiazem can slow the rate. It cannot be terminated by cardioversion because there is no single reentrant circuit to reset, and digoxin does not convert it. Magnesium infusion is a useful adjunct.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.