A 68-year-old man with severe COPD exacerbation has an irregular narrow-complex tachycardia at 120 bpm. ECG shows at least three distinct P wave morphologies with varying PR intervals and an isoelectric baseline between P waves. He is not hypoxic and electrolytes are normal. What is the most appropriate initial management?
- A Immediate synchronized cardioversion
- B IV adenosine to terminate the rhythm
- C Treatment of the underlying pulmonary disease ✓
- D Radiofrequency ablation of the focal driver
Correct answer: C. Treatment of the underlying pulmonary disease
Explanation
Multifocal atrial tachycardia shows three or more P wave morphologies with variable PR intervals and an isoelectric baseline, distinguishing it from atrial fibrillation which lacks organised atrial activity. It occurs almost exclusively in elderly patients with advanced lung disease, and therapy is directed at correcting hypoxia, bronchospasm and acid-base disturbance. Cardioversion is ineffective because multiple automatic foci cannot be reset, and adenosine only transiently slows AV conduction without terminating the rhythm.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.