Contributor: Taylor Lynch, MD

Educational Pearls:

What is atrial fibrillation with rapid ventricular response (AFib with RVR) and how does it differ from atrial fibrillation (AFib)?

• AFib is an abnormal heart rhythm in which the heart has disorganized atrial electrical activity. This causes the atria to quiver with only select signals being conducted through the Atrioventricular (AV) Node to reach the ventricles and result in ventricular contraction.
• Often described as "irregularly irregular", a patient's EKG will present with no discernible P-waves, and irregular R-R intervals.
• AFib with RVR is distinguished from AFib when the patient's ventricular rate is greater than 100-110 beats per minute in AFib with RVR.

What is the treatment for AFib with RVR?

• Diltiazem is considered one of the first line therapeutic agents in the treatment of AFib with RVR.
• Diltiazem inhibits L-Type calcium channels in the AV Node, reducing the amount of signals conducted to the ventricles, thus reducing the ventricular rate.

Why pretreat patients receiving Diltiazem for AFib with RVR with calcium?

• While diltiazem inhibits cardiac calcium channels, it may also cause peripheral vasodilation, resulting in diltiazem-induced hypotension.
• A recent study found that this hypotension can be blunted by pretreating with 1-2g IV Calcium Chloride (IV Calcium Gluconate can be used in the ED).
• Calcium is thought to peripherally stabilize the vascular smooth muscle, preventing vasodilation without impacting the desired calcium channel blocker action at the AV node.

Key takeaways?

• In combination with slower pushes of diltiazem for patients in AFib with RVR (AFib with ventricular rate >100-110 bpm) with borderline low blood pressures, 1-2 g of IV Calcium Gluconate can combat diltiazem induced hypotension peripherally without negating the cardiac effect of diltiazem to reduce the heart rate.

References

1. 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2024;149(1):e1-e156. doi:10.1161/CIR.0000000000001193
2. Az A, Sogut O, Dogan Y, et al. Reducing diltiazem-related hypotension in atrial fibrillation: Role of pretreatment intravenous calcium. Am J Emerg Med. 2025;88:23-28. doi:10.1016/j.ajem.2024.11.033

Summarized by Dan Orbidan, OMS2 | Edited by Dan Orbidan and Jorge Chalit, OMS4

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