Medication Pearls for Atrial Fibrillation Management in the ED

Today’s pearl highlights 5 main points related to the treatment of atrial fibrillation.

Should you give a beta blocker or a calcium channel blocker? What dose should you use?

1. Determining which negative inotrope to choose is challenging. I’ve seen more cases of difficult-to-treat atrial fibrillation (afib) at MGH in 4 years than I did at Maryland in 8 years. Back in 2014, a cardiology pharmacist colleague (Dr. Brent Reed) and I collaborated for a two-part ALiEM series on choosing a beta blocker (BB) or a calcium channel blocker (CCB) for afib in the ED. My discussion focused on what to do in the ED. His focused on thinking beyond the ED. Though they are 6 years old, the principles still hold true in 2020.
2. In the patient with borderline blood pressure, but not really appropriate for emergent cardioversion, there is some evidence to support giving calcium prior to a CCB to maintain blood pressure (without affecting our ability to control HR). The evidence is largely with verapamil, but may also apply to diltiazem. Here’s a summary of the data. I like to recommend giving calcium gluconate 2 gm over 10-20 minutes followed by the CCB.
3. What happens when we give multiple doses of one agent and it doesn’t work? Can we safely switch to a different agent? What about heart block and/or bradycardia? At MGH, we actually switch from BB to CCB (and vice versa) often enough that were able to study it. We found that 4% of patients developed bradycardia (n = 136). This result can be looked at from the perspective of only 4% of patients were negatively affected or wow, 4% of patients were negatively affected! Importantly, adding a second nodal blocker in patients who did not achieve rate control with the first agent resulted in heart rate control in less than half of cases.
4. What dose of diltiazem is correct? Both weight-based and non-weight-based strategies have been studied. Here’s a summary of the data from a previous MGH EM pharm pearl.
5. We’ve significantly decreased our utilization of diltiazem infusions in the ED over the past few years (a good thing). Here’s a nice overview of why diltiazem infusions are not ideal for acute rate control, especially in patients with underlying cardiovascular disease.

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