Review Question - QID 102954

This patient presents with a likely COPD exacerbation (given his history of COPD, wheezing, and hypoxia) and is found to have multifocal atrial tachycardia on ECG which is best managed with diltiazem.

Multifocal atrial tachycardia (MAT) is an arrhythmia most closely associated with severe underlying lung disease such as COPD. It is characterized on ECG by a rapid rate with at least 3 distinct P wave morphologies preceding the QRS complexes. Other etiologies for MAT include electrolyte disturbances (especially hypokalemia and hypomagnesemia), and medication effects (such as from isoproterenol and the phosphodiesterase inhibitors theophylline and aminophylline). The management is to first treat the COPD flare with steroids, nebulizers, and BiPAP. The best rate control agent is a calcium channel blocker such as diltiazem or verapamil. Beta blockers are generally not preferred as they could lead to bronchospasm given their beta-2 blockade.

Figure/Illustration A is an ECG with at least three distinct P wave morphologies (blue circles) in the setting of tachycardia.

Incorrect Answers:
Answer 1: Amiodarone is an anti-arrhythmic agent that could be used for rhythm control in atrial fibrillation. It is generally not preferred when compared to rate control.

Answer 2: Aspirin is the best initial step in management when a patient presents with chest pain (when there is suspicion for acute coronary syndrome).

Answer 3: Digoxin is a rate control agent that blocks the AV node and may be used 2nd line in atrial fibrillation. It increases myocardial oxygen demand; however, it also increases cardiac contractility (which is useful when patients are borderline hypotensive).

Answer 5: Metoprolol is an appropriate agent for treating arrhythmias such as atrial fibrillation with rapid ventricular response; however, it generally should be avoided in COPD given that it could cause bronchospasm (or at least reduce the efficacy of albuterol).

Bullet Summary:
Multifocal atrial tachycardia is best treated with oxygen, steroids, albuterol-ipratropium nebulizers (for the underlying lung disease such as COPD), and a rate control agent such as verapamil or diltiazem.