A lesson I learned caring for a recent patient: CHF exacerbation in Afib with RVR
Clinical Question: What is the best way to rate control in decompensated heart failure?
Our first instinct when we see patients with A-fib with RVR is to reach for diltiazem or our beta blocker of choice, however, these are not the best choice in this subset of patients.
From the 2014 AHA/ACC Guidelines: “For rate control, intravenous nondihydropyridine calcium channel antagonists, intravenous beta blockers, and dronedarone should not be administered to patients with decompensated HF”. (Class III causing harm, level of evidence of C). While these drugs may slow the rate, they also exert anti-ionotropic effects that can reduce the patient’s already diminished cardiac output.
Instead, “in the absense of pre-excitation, intravenous digoxin or amiodarone is recommended to control heart rate acutely in patients with HF” (Class I, LoE B).
Digoxin – 0.25 mg IV w/ repeat dosing to a maximum of 1.5 mg over 24 hr
Amiodarone – 300 mg IV over 1 hr, then 10-50 mg/hr over 24 hr (this is different from the default order in Epic)
If in doubt you can always put the US on the patient’s heart – if the squeeze looks poor you are better off avoiding CCBs/BBs.
Full guidelines can be found here, CHF recs are in section 6.6 – http://content.onlinejacc.org/article.aspx?articleid=1854230
Anyone have any other tips or recommendations for caring for these challenging patients?
The amiodarone dosing is interesting and different than the usual dose which is supplied later in the document “IV: 150 mg over 10 min; then 1 mg/min for 6 h; then 0.5 mg/min for 18 h or change to oral dosing” I would question if can achieve rate control in the ED with an amiodarone dose of 300 mg over 1 hour. Think concentrations will not be large enough to have acute rate control effect.
Digoxin may not be harmful with decompensated AF but also may not be as effective outside of elderly and non-active patients. Works to increase vagal tone which may be overridden by younger, more active patients. Also it is not a medication without risk; doses have to be pushed closer to the edge of toxicity 1.8 to 2 mcg/ml and watch for significant drug interactions with amiodarone and CCB (if on either PTA), transplant meds, and other antiarrhythmic agents.
My interpretation is Amio 150mg IV over 10 min then 1mg/min for 6 h is for the maintenance of sinus rhythm after conversion. Whereas the dose of 300mg over 1 hr then 10-50 mg/hr over 24 hours is for rate control.
In Epic it recommends the 150 dosage.
John, are we able to confirm which dosage is for which indication?
No dose is FDA approved. Based on the literature it is difficult to say what may is best. Either dose has been used for cardioversion and there are other doses that have been studied: 5 mg/kg over 30 min, 450 mg over 1 min, 125 milligrams/hour for 24 hours, and other doses as well. These doses were compared to other agents and studies were small between 10 and 200 patients. If the patient is not hypotensive I would recommend 150 mg over 10 min or 5 mg/kg over 30 min.