What is the first line treatment for rate control in a patient with Chronic Obstructive Pulmonary Disease (COPD) and Multifocal Atrial Tachycardia (MAT) presenting with tachycardia?

Rate Control for MAT in COPD Patients

Verapamil or diltiazem are the preferred first-line agents for rate control in COPD patients with multifocal atrial tachycardia, as these calcium channel blockers do not exacerbate pulmonary disease and can effectively slow ventricular response. 1

Primary Treatment Approach

First-Line: Calcium Channel Blockers

• Intravenous verapamil can be useful for acute rate control in MAT, with the ability to both slow ventricular response and potentially terminate the arrhythmia (converted MAT in 8 of 16 patients in one study). 1

• Verapamil has the critical advantage of not exacerbating underlying pulmonary disease, making it particularly suitable for COPD patients. 1

• Diltiazem is reasonable as an alternative, though it has not been specifically studied in MAT; it is expected to provide similar benefits through the same mechanism as verapamil. 1

• The major potential side effect to monitor is hypotension. 1

Contraindications to Calcium Channel Blockers

• Do not use verapamil or diltiazem if the patient has:
  • Severe conduction abnormalities 1
  • Sinus node dysfunction 1
  • Acute decompensated heart failure 1
  • Hemodynamic instability 1

Alternative: Beta-Blockers (Use with Caution)

When Beta-Blockers May Be Considered

• Metoprolol (a cardioselective beta-blocker) is reasonable for rate control in MAT, but requires careful patient selection in COPD. 1

• Beta-blockers can be used only after correction of hypoxia or other signs of acute respiratory decompensation. 1

• Small studies have shown that metoprolol achieved rate control or conversion to sinus rhythm in patients with serious pulmonary disease after stabilization. 1

Critical Contraindications for Beta-Blockers

• Avoid beta-blockers in patients with:
  • Severe bronchospastic pulmonary disease 1
  • Active respiratory decompensation 1
  • Acute decompensated heart failure 1
  • Severe conduction abnormalities 1
  • Sinus node dysfunction 1

Essential First Steps Before Rate Control

• Treat the underlying condition first - this is the primary management strategy for MAT. 1

• Correct hypoxia and metabolic abnormalities before initiating rate control medications. 1

• Administer intravenous magnesium, which may be helpful even in patients with normal magnesium levels. 1

• Evaluate for and address: pulmonary disease exacerbation, pulmonary hypertension, coronary disease, valvular disease, hypomagnesemia, and theophylline toxicity. 1

Important Clinical Pitfalls

• Cardioversion is not useful in MAT - do not attempt electrical cardioversion as it will not be effective. 1

• Antiarrhythmic medications are generally not helpful for suppressing multifocal atrial tachycardia. 1

• The irregular-irregular pulse may be difficult to distinguish from atrial fibrillation on physical exam alone - obtain a 12-lead ECG to confirm MAT diagnosis (look for ≥3 distinct P-wave morphologies with isoelectric periods between P waves). 1

• In COPD patients, MAT may occur at rates as low as 90 bpm rather than the traditional 100 bpm threshold. 2