atrial fibrillation

• related: tachycardia, Arrythmia, Cardiology
• tag: #note

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epidemiology

• most common sustained arrhythmia
• affect more than 33 million persons worldwide
• Lifetime risk for atrial fibrillation is 25% in patients older than 40 years.
• Incidence is strongly associated with and increases with age.
• 10% of persons older than 80 years.
• fivefold increased risk for stroke
• increased risk for heart failure and dementia
• Among patients aged 55 years and older who have a cryptogenic ischemic neurologic event, such as a stroke or transient ischemic attack, occult intermittent atrial fibrillation is thought to be present in up to 25% of cases, and 30-day ambulatory ECG monitoring is indicated for detection. If 30-day ambulatory monitoring is inconclusive, implantation of a cardiac monitor (loop recorder) is reasonable to optimize detection of silent atrial fibrillation.

risks

• DM
• obesity
• HTN
• CAD
• HF
• sleep apnea
• smoking
• alcohol consumption

Duration

• paroxysmal: stops within 7 days
• persistent: last for 7 days or more
• long standing persistent: > 1 year

Management

unstable

• synchronized cardioversion: avoids R on T event and Vfib
• unknown duration or > 48 hours duration: initiate AC and continue for 4 weeks at least

stable

• testing
  • TSH
  • sleep apnea
  • echocardiogram for valvular or structural heart disease, left atrial size

Rate control

• goal:
  • <60
  • <110 in pts without lower EF

Rhythm control

• pill-in-the-pocket approach: pts with infrequent afib and no structural heart disease
  • on BB/CCB
  • flecainide/propafenone: take at onset of episode
  • fleicanide: need AV nodal blockade such as BB to avoid 1:1 Vfib from Afib
  • Class 1c: need ischemic work up prior to initiate in hospital. Could also initiate then ischemic work up afterwards
  • Class 3: watch out for QTc prolongation (sotalol)

Ablation

• for symptomatic afib despite antiarrythmic
• pulmonary vein isolation
• AV nodal ablation: afib with tachycardia despite rate/rhythm control. Needs permanent pacemaker. Also will remain in afib afterwards and still need AC](##)

cardioversion

• pharm cardioversion: pt without structural heart disease
  • can use Ibutilide: monitor on tele for 6 hours or until QTc return to baseline due to small risk of torsades

anticoagulation

When to start

• afib duration < 48 hours or low risk for stroke/thrombus
  • preprocedural AC for men with chadsvasc more than 1 and women more than 2
• unclear duration or > 48 hours
  • AC for 3 weeks before cardioversion
  • can use TEE prior to cardioversion
• Continue at least 4 weeks following cardioversion due to increased risk for thrombus formation after sinus rhythm

Valvular vs Nonvalvular

• non-valvular afib: base on CHA2DS2-VASc
  • men: AC if score ≥ 2
  • women: AC if score ≥ 3
  • other valves: aortic valve, MR, TR, mild mitral stenosis
  • can use non-vitamin K antagonist (NOAC)
• valvular afib: needs AC
  • mechanical prosthesis (mechanical valve replacement)
  • moderate to severe MS
  • cannot use NOAC, only warfarin
• Pt with HAS-BLED ≥ 3 needs regular evaluation

Agents

• Warfarin
  • INR goal 2-3
• NOAC
  • kidney/liver function, reevaluate at least annually
  • dabigatran: thrombin inhibitor, Pradaxa
    • less intracranial bleed
    • higher GI bleed
    • dyspepsia
  • rivaroxaban: 10a inhibitor, Xarelto
    • noninferior to warfarin with stroke or embolism
    • less intracranial/fatal bleed
    • higher GI bleed risk
  • apixaban: 10a inhibitor, Eliquis
    • superior for stroke prevention
    • less major bleed risk
    • less intracranial bleed risk
  • edoxaban:
    • noninferior for stroke prevention
    • less major bleed
  • reversal agents
    • andexanet alfa or 4-factor PCC: for life-threatening bleed 2/2 10a inhibitors
    • Idarucizumab: for dabigatran, emergency invasive procedures or life threatening bleeds
• left atrial appendage occlusion: can consider in pt with CHADSVASC ≥ 3
  • lower risk for intracranial bleed
• for pts with afib s/p PCI and CHADSVASC ≥ 2
  • double therapy: clopidogrel/ticagrelor + AC
  • better than triple therapy to reduce risk of bleed
• for pts with afib and stable CAD
  • xarelto alone instead ASA + rivaroxaban