A 70-year-old man with an acute exacerbation of COPD has an irregular narrow-complex tachycardia at 125 bpm. ECG shows at least three distinct P wave morphologies with varying PP, PR and RR intervals. He is normotensive. Which agent is preferred if pharmacologic rate control becomes necessary?
- A Intravenous metoprolol
- B Verapamil or diltiazem ✓
- C Digoxin
- D Amiodarone oral loading
Correct answer: B. Verapamil or diltiazem
Explanation
Multifocal atrial tachycardia is defined by three or more P wave morphologies with irregular intervals and occurs almost exclusively in severe pulmonary disease. Primary treatment is correction of hypoxia, bronchospasm and electrolyte disturbances. When drug therapy is needed, a nondihydropyridine calcium channel blocker is preferred. Beta blockers risk bronchospasm, digoxin does not slow this tachycardia effectively and carries toxicity risk in hypoxic patients, and amiodarone is reserved for refractory cases.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.