30  Atrial Fibrillation

Important

If HD unstable or intractable ischemia → immediate DC cardioversion

30.1 Note

Atrial Fibrillation, (*** paroxysmal/persistent/permanent)
- Echo: ***
- CHADS2-VASc score: ***
- HAS-BLED score: ***
- R/R control: ***
    - Goal resting HR < 110 bpm (if Asx and preserved LVEF) [RACE II trial]
    - Goal resting HR < 80 bpm for Sx AF mgmt despite "lenient" rate control [RACE II trial]
    - If recent Dx (within 1 yr), consider rhythm control [EAST-AF trial]
- Anticoagulation: ***
    - Indicated if no significant bleeding risk and CHADS2-VASC >= 2 (men), >= 3 (women)
    - If CKD 5/ESRD -> warfarin or apixaban (5 mg BID unless TBW < 60 kg or Age > 80 yo)
- Consider checking TSH/fT4, Lytes (inc Ca, Mg)
- Treatment of other co-moribidities
    - OSA, HTN, Obesity, EtOH use disorder
- Encourage weight loss (if obese) and abstinence from alcohol (Voskoboinik et al., NEJM 2020)

30.2 Classifications

  • Paroxysmal - terminates spontaneously or with intervention in < 7 days; recurrence may occur
  • Persistent - continuous AF lasting > 7 days; requires termination by cardioversion/ablation
  • Permanent - AF > 7 days; sinus rhythm not possible, refractory to cardioversion

30.3 Anticoagulation

Warning

Avoid DOACs in patients with mechanical ❤️ valves (RE-ALIGN).

  • DOACs for AFib
    • Dabigatran: RE-LY
    • Rivaroxaban:ROCKET-AF
    • Apixaban: ARISTOTLE
  • Perioperative management: often we do not need to bridge AC peri-procedurally. (Douketis et al. 2015, 2019)

30.4 Rate Control Drugs

  • Metoprolol tartrate: up to 200 mg BID
  • Metoprolol succinate: up to 400 mg daily
  • Carvedilol 3.125-25 mg BID
  • Bisoprolol 2.5-10 mg daily
  • Diltiazem (extended-release) 120-360 mg daily
  • Digoxin: TODO

European Society of Cardiology and NICE guidelines recommend combination therapy if a single agent fails to control HR

30.5 Rhythm control

  • EAST-AFNET 4 trial (kirchhof2020?)

    • Early rhythm control within 1 yr of AF Dx with antiarrhythmics or AF ablation (+ cardioversion of persistent AF) was associated with reduced risk of CV mortality, stroke, HF hospitalization, or ACS hospitalization (compared to rate-control)

    • Great CardioNerds Journal Club on EAST-AFNET 4 trial

30.6 RVR management

  • IV metoprolol 2.5-5 mg over 2 minutes every 5 mins (up to 3 doses)
  • Dilt gtt (if EF preserved)
  • Amiodarone 300 mg over 1 hr, then maintenance over 24 hrs

Formula to convert diltiazem gtt to PO dilt: \(\text{PO} = [(\text{IV (mg/hr)} \times 3) + 3] \times 10\). For example, if rate controlled on dilt gtt at 5 mg/hr → PO = 18 x 10 = 180 mg/day.

30.7 Risk factors

  • Modifiable risk factors

    • OSA
    • HTN
    • EtOH use disorder

30.8 Drugs that may cause/exacerbate AFib

30.9 Cardioversion Rules

  • If AFib d/t thyrotoxicosis, cardioversion is often unsuccessful before restoration of a euthyroid state

  • TEE + therapeutic anticoagulation → cardioversion → at least 4 weeks of therapeutic anticoagulation (indefinitely if increased stroke risk)

  • Therapeutic anticoagulation x3 wks → cardioversion → at least 4 wks of therapeutic anticoagulation

  • If duration of AFib < 48 hrs

    • If HD unstable → just cardiovert, i.e. don’t waste time w/ anticoagulation

    • If HD stable → start on VTE-dose ppx before cardioversion