inpatient / cardiology
Atrial Fibrillation
# (Paroxysmal/Persistent) Atrial Fibrillation *** with RVR
Checklist
-- ABCs: is the patient unstable requiring pressors or need for cardioversion?
-- Chart Check: prior EKG, echo, cardioversion attempts, ablation, TSH, AC use
-- HPI Intake: AC use and adherence, caffeine and EtOH use, hyperthroid symptoms
-- Can't Miss: shock, MI, sepsis
-- Admission Orders: telemetry, EKG, TSH, LFTs, coags, trop, NT-proBNP, consider UDS, echo
-- Initial Treatment to Consider: IVF --> metop/dilt --> amdioarone if right patient --> pressor --> cardioversion; Abx if c/f sepsis
Assessment:
-- History: *** CHADS-VASc: *** (CHF, HTN, Age>75 x 2, DM, stroke x 2, vascular disease (prior MI/PAD/aortic plaque), Age 65-74, sex category (female but only gets score if has another point); AC: *** (DOAC or warfarin if >2), any missed in last month
-- Clinical: *** tachycardia, chest pain, dyspnea, evidence of hyperthyroidism
-- Exam: *** distress, WOB, murmurs, S3/S4, crackles, volume assessment (JVP, edema, POCUS)
-- Data: *** EKG, CXR, Echo, coags, TSH, trop, NT-proBNP
-- Etiology/DDx: *** ischemia, heart failure, hypovolemia, PE, COPD, sepsis, hyperthyroid, EtOH, drugs
Plan:
Workup
-- New Afib - CBC, BMP, Mg/Phos, TSH, LFTs, Coags, Troponin, NT-proBNP, UDS
-- Echo is c/f change in cardiac function or planning for cardioversion (TEE)
-- If new afib, ensure patient has cardiology follow up to assess persistent afib and to consider cardioversion - goal is to get TFTs, holter, echo, 2-3 weeks cardiology follow up
Treatment
-- Rate: metop 5mg IV x3 (if HR >130 or sxs and BP allows) → 12.5mg (25mg if did not respond to initial 5mg IV push) PO q6 (max 400mg daily); diltiazem 0.25mg/kg bolus (max dose 25mg), rebolus after 15 minutes if need be → infusion rate 2.5-15mg/hour --> PO ER at dose roughly equal to 10[3(infusion rate in mg/hr) +3] (to max 360mg daily, avoid in HF)
-- Rhythm: amiodarone (full load is 10g) - 150mg bolus 1-3x until converts → drip 1mg/min for 6 hours → 0.5mg/min → 400mg PO BID --> 200mg PO BID; usually do not keep on amiodarone long term due to side effects once patient has flipped back into sinus rhythm
-- AC: *** (DOAC preferred, apixaban for renal impairment, warfarin for mitral-stenosis, mechanical valve, HOCM)
-- IVF PRN as tolerated
-- Keep K >4, Mg >2
-- Pressor: start with phenylephrine (neo)
-- DCCV: if >48 hours and have not reliably been on DOAC for 3-4 weeks, need TEE; otherwise DOAC 3-4 weeks before and 4 weeks after
-- Ablation - consider within 1 year of new diagnoiss in patients who have not been chemically converted
-- Watchman - consider in non-valvular AF if higher bleed risk (though note the need AC for 6 weeks after placement)
PDF coming soon!
If You Remember Nothing Else
In general, it's okay for patients to be in AFib in the hospital unless it leads to RVR and/or instability. Afib with RVR is unlikely to be the sole source of hypotension unless HR is >150, so keep in mind other etiologies that can precipitate Afib and RVR (MI, heart failure, hypovolemia, PE, sepsis) and treat the underlying disease. Start with IVF and BB/CCB pushes, then trial amiodarone to cardiovert and prevent flipping back into afib, then add pressors (phenylephrine as first line), and then electrically cardiovert if the patient remains unstable. Avoid rhythm control unless emergent if the Afib has been present for >48 hours, or the patient has not been on AC for at least 3-4 weeks due to the risk of throwing a clot from the LAA. Historically, rate control was preferred to rythm control, however with the wider availability of ablation, an early rythm control may be the ideal standard in many patients.
Clinical Pearls
- Afib is irregularly irregular ryhthm without p-waves; is different than multifocal atrial tachycardia
- Afib is Paroxysmal if self terminates within 7 days, Persistent if it lasts longer than 7 days, and the term Permanent is used only when the decision is made to stop any further attempts for achieving sinus rythm
- Everyone with new afib deserves an early attempt at sinus rhythm either through chemical or electrical cardioversion
- Make sure it’s actually afib and not just sinus rhythm with lots of PACs - look for the p-waves!
- BB > CCB for rate control (70% vs 54%); Do not use diltiazem (CCB) in patients with heart failure
- Should use procainamide for rate control if pre-excitation (WPW) present
- Get baseline LFTs and TFTs before starting amiodarone; Amiodarone can cause pulmonary fibrosis
- Amiodarone can still lead to hypotension initially, especially when bolused
- Afib with RVR is unlikely to be the cause of hypotension alone unless HR >150; though a fib can also reduce preload via reduced “atrial kick” since no coordinated p-wave
- The first pressor should be phenylephrine (avoids adrenergic agonism and can lead to reflex bradycardia); it doesn't make sure to use levo, especially if you had previously been giving beta blockers
- In general, there is a risk of embolic stroke if any breaks in AC from one month prior to cardioversion
- The left atrial appendage is the source of ~90% of thombi who have CVA with AFib
- Ablation is more effective than antiarrhythmics for maintaining sinus rhythm
- Pill-in-pocket options - flecainide, propafenone
- Atrial flutter treated similarly, but tougher to successfully rate control and it will stay in the 150 range which represents the 2:1 transmission through the AV node; usually need to ablate the cavo-tricuspid isthmus
- CHADS-VASc and AC use in afib is not really validated in critically ill patients and is a much more nuanced decision based on risks and benefits
Trials and Literature
- AFFIRM Trial - rate control non-inferior to rhythm control - for sxs, CV mortality, stroke risk; should still consider rhythm control if bad sxs, age <65, or HFrEF (NEJM, 2002)
- EAST-AFNET 4 Trial - rhythm control (antiarrhythmic or ablation) superior to rate control if diagnosed with AF in the last year (NEJM, 2020)
- CABANA Trial - catheter ablation did not decrease MACE in afib for all-comers (JAMA, 2019)
- CASTLE-AF - ablation decreased composite of death from any cause or hospitalization for worsening heart failure in patients with afib and HFrEF with EF <35% who did not respond to antiarrythmic drugs (NEJM, 2018)
- RACE II Trial - lenient rate control (HR<110) non-inferior to strict (HR<80), but strict may be better in younger patients and those with HF (NEJM, 2010)
Other Resources
- MD Calc - CHADS-VASc (one year risk of thromboembolic event in non-anticoagulated patient); HAS-BLED (risk of bleed on DOAC)
- The Curbsiders Podcast - #363 Afib: Rythm Control, Catheter Ablation, Afib in the Hospital, and LAA Closure
- Internet Book of Critical Care - Atrial Fibrilation and Flutter Complicating Critical Illness
