What is the acute management of atrial fibrillation (AFib) with rapid ventricular response (RVR) in a stable patient on metoprolol (Lopressor) 12.5mg twice daily (bid)?

From the Guidelines

For acute management of atrial fibrillation with rapid ventricular response (AFib with RVR) in a stable patient already on metoprolol 12.5mg twice daily, I recommend increasing the beta-blocker dose to achieve heart rate control. The most recent and highest quality study to guide this decision is the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1. According to this guideline, control of the ventricular rate using a beta blocker or nondihydropyridine calcium channel antagonist is recommended for patients with paroxysmal, persistent, or permanent AF.

Key Considerations

• The patient is already on metoprolol, suggesting this is the preferred agent, but the current dose is insufficient.
• Rate control is the immediate priority in stable patients, while decisions about rhythm control and anticoagulation should follow once rate is adequately controlled.
• The target ventricular rate should usually be less than 110 bpm, as implied by the need to control symptoms and prevent hemodynamic distress.

Recommended Approach

• First, administer additional metoprolol 5mg IV slowly over 2-5 minutes, which can be repeated every 5 minutes for a total of 15mg as needed to achieve heart rate control.
• Then, increase the oral metoprolol dose to 25mg twice daily.
• If the patient remains in AFib with RVR despite these measures, consider adding diltiazem 0.25mg/kg IV over 2 minutes, followed by an infusion at 5-15mg/hour if needed, as suggested by the European Society of Cardiology guidelines 1.

Monitoring and Adjunctive Care

• Ensure continuous cardiac monitoring during acute treatment.
• Check electrolytes (particularly potassium and magnesium).
• Obtain a 12-lead ECG to confirm the diagnosis. By following this approach, the patient's heart rate can be effectively controlled, reducing the risk of morbidity and mortality associated with uncontrolled AFib with RVR.

From the Research

Acute Management of AFib with RVR in a Stable Patient on Metoprolol

• The patient is already on metoprolol 12.5mg bid, which is a beta blocker used for rate control in atrial fibrillation (AF) with rapid ventricular response (RVR) 2, 3, 4.
• Studies have shown that diltiazem, a calcium channel blocker, may achieve rate control faster than metoprolol, although both agents are safe and effective 2, 5.
• In patients with heart failure with reduced ejection fraction (HFrEF), the use of calcium channel blockers like diltiazem may be associated with a higher incidence of worsening heart failure symptoms compared to metoprolol 6.
• The choice of rate control agent should be based on individual patient factors, clinical situation, and comorbidities 2, 3.
• Sustained rate control can be achieved with both metoprolol and diltiazem, with no significant difference in success rates between the two agents 5.

Considerations for Rate Control

• The goal of rate control is to slow the ventricular rate to less than 100 beats per minute without compromising cardiac output 3, 4.
• Intravenous beta blockers or calcium channel blockers can be used for acute rate control in the emergency department setting 2, 3, 4.
• The selection of a rate control agent should take into account the patient's hemodynamic stability, comorbidities, and potential side effects of the medication 2, 3, 6.

Monitoring and Adjunctive Therapy

• Patients with AF and RVR should be monitored for signs of hemodynamic instability, such as hypotension or cardiac ischemia 3, 4.
• Anticoagulation therapy should be considered in patients with AF and RVR to reduce the risk of stroke and other thromboembolic events 3.
• Elective cardioversion may be considered in select patients with AF and RVR who are hemodynamically stable and have no contraindications to the procedure 3.