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Atrial Fibrillation & Flutter

Matt Gayoso

Background

  • AF: 12-lead EKG with absence of p-waves and irregularly irregular QRS complexes
  • Flutter: sawtooth atrial F waves (300 BPM) with regular or regularly irregular QRS complexes
  • Ventricular rate ratio of F waves: V waves ~150 (2:1), ~100 (3:1), or ~75 (4:1)
  • 3 classifications
    • Paroxysmal (terminates within 7 days)
    • Persistent (persisting beyond 7 days)
    • Permanent (normal rhythm cannot be restored)
  • Rapid ventricular response (RVR) is HR > 100 (ie AF/Flutter w/ tachycardia)
  • AF/RVR is far more often a consequence of hypotension than the cause of it

Evaluation

  • Causes: Mnemonic “H PIRATES”
    • Hypertension
    • Pneumonia, Pericarditis, Post-op
    • Ischemia (rare)
    • Rheumatic Valve
    • Atrial Myxoma or Accessory Pathway
    • Thyrotoxicosis
    • Ethanol or Excess Volume
    • Sick sinus, Sepsis

Management

  • Treatment goals
    • Rate control, Goal HR \< 110 (RACE II)
    • Rhythm control (if indicated)
    • Stroke prevention (CHADS2VASc)

Rate control:

  • RVR ~ sinus tach of AF; Always work to address the underlying cause (infection, volume overload, etc). Rate control is rarely an emergency unless the patient is unstable
  • If stable with RVR (SBP >90)
    • IV if HR > 130 or symptomatic (metop 5 mg IV or dilt 15-20 mg IV), otherwise do PO
    • AV nodal blocking agents
      • B-blockers: Start with metop tartrate (titratable) consolidate to succinate. Avoid in decompensated or borderline HF
      • Calcium channel blockers (diltiazem): avoid in HFrEF
  • Peri stable (SBPs 80s-90 with preserved perfusion)
    • Amiodarone: Consider if decompensated HF, accessory pathway, anti-coagulated. Caution that you may cardiovert pt (stroke risk)
  • Unstable (SBPs \<80)
    • Cardioversion

Rhythm control

  • New onset a-fib (first time diagnosis): most pts will be a candidate for trial of cardioversion
  • If onset clearly within 48 hours, can proceed without TEE. Often TEE is done anyway (pt may have had intermittent asymp AF)
  • If onset >48 hours or unclear, will need TEE to rule out LAA thrombus
  • Pharmacologic options include class 1C: flecainide, propafenone (avoid in structural heart disease) and class 3: Amiodarone, dronedarone, sotalol, ibutilide, dofetilide (some require loading inpt)
    • Caution using antiarrhythmics in any pt you wouldn't electrically cardiovert without TEE
  • Consider EP consult for ablation in symptomatic paroxysmal or persistent AF refractory to anti-arrhythmic drugs, AF in HFrEF, or flutter

Stroke Prevention (for AF and flutter)

  • CHA2DS2-VASc risk score >2 in M or >3 in F should prompt long term AC in AF persisting >48 hours
  • DOACs (apixaban, dabigatran, edoxaban, rivaroxaban) are preferred to warfarin except in moderate to severe MS or mechanical valve
  • If cardioversion planned for new onset AF, start AC as soon as possible
  • Post-cardioversion, anticoagulate for at least 4 weeks due to atrial stunning and stroke risk
  • If no contraindications or procedures, continue anticoagulation while inpatient
  • Typically do not need to bridge AC for AF in the setting of procedures unless mechanical valve is present. Decide on a case by-case basis
  • Left atrial appendage closure can be considered in those with increased risk of bleeding (WATCHMAN, Amulet devices)