Achieving ventricular rate control in patients taking chronic beta-blocker therapy

Area of Science:

• Cardiology
• Emergency Medicine
• Pharmacology

Background:

• Atrial fibrillation with rapid ventricular rate (AF with RVR) is common in emergency departments.
• Patients on chronic beta-blocker therapy present unique challenges for rate control.
• Intravenous (IV) metoprolol and diltiazem are commonly used for acute rate control.

Purpose of the Study:

• To compare the efficacy of IV metoprolol versus IV diltiazem for ventricular rate control.
• To evaluate outcomes in patients with AF with RVR already on chronic beta-blocker therapy.

Main Methods:

• Retrospective, single-center study.
• Included adult patients on chronic oral metoprolol within 5 days of presentation.
• Defined successful rate control as <100 bpm or <120 bpm with a ≥20% decrease in heart rate.

Main Results:

• 68.8% of diltiazem patients achieved rate control vs. 42.4% of metoprolol patients (p=0.067).
• IV metoprolol was associated with significantly more hospital admissions (58% vs. 6.25%, p<0.001).
• Diltiazem use led to a higher incidence of bradycardia (13% vs. 0%, p=0.002).

Conclusions:

• IV diltiazem demonstrated a higher response rate for ventricular rate control compared to IV metoprolol.
• The difference in response rates did not reach statistical significance.
• Diltiazem may be a preferable option for acute rate control in this patient population, despite a higher risk of bradycardia.