Atrial Fibrillation & Flutter

Michael Daw

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)
  • 4 classifications
    • Paroxysmal (intermittent and terminates <7 days)
    • Persistent (continuous >7 days)
    • Longstanding persistent (continuous for >12 months)
    • Permanent (normal rhythm cannot be restored or no further attempts to restore it)
  • Rapid ventricular response (RVR) is HR > 100 (i.e. 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, Electrolytes, or Excess Volume, Sick sinus, Sepsis, Additional causes: Lung disease (COPD, asthma, smoking), OSA, obesity

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 pt is unstable
    • Unstable (SBP <80): Cardioversion
    • Stable (SBP >90): IV AV nodal blockers if HR > 130 or symptomatic (metop 5mg IV or dilt 15-20mg IV, every 15 minutes up to 3x), otherwise opt for PO
      • B-blockers: Start with metop tartrate (titratable) -> consolidate to succinate. Avoid in decompensated or borderline HF
      • Calcium channel blockers (diltiazem): DO NOT give in HFrEF
    • Peri stable (SBPs 80-90s w/ preserved perfusion)
      • Amiodarone: Consider if decompensated HF, anti-coagulated. Caution that you may cardiovert pt (stroke risk)
      • Digoxin: consider if decompensated HF, will require IV loading dose prior to transition to PO. Will need to monitor digoxin levels
    • Avoid AV nodal blockers and amiodarone in AF with preexcitation (WPW) as these can trigger Vfib, consider procainamide in consultation with cardiology

Rhythm Control

  • Consider in new onset AF (first time diagnosis), symptomatic AF, younger patients, high cardiovascular risk, or heart failure not acutely decompensated (EAST-AFNET 4)
  • If onset clearly within 48h, can proceed without TEE. Often TEE is done anyway (pt may have had intermittent asymp AF)
  • If onset >48h or unclear, will need TEE to rule out LAA thrombus; you can also anticoagulate for 3 weeks prior to TEE if unable to get TEE.
  • Pharmacologic options include class 1C: flecainide, propafenone (avoid in structural heart disease) and class 3: Amiodarone, dronedarone, sotalol, ibutilide, dofetilide (some require loading inpt)
    • o Caution using antiarrhythmics in any pt you wouldn’t cardiovert without TEE
  • Consider EP consult for ablation in symptomatic paroxysmal or persistent AF refractory to anti-arrhythmic drugs, AF in HFrEF, or flutter in outpt setting

Stroke Prevention (for AF and Flutter)

  • If cardioversion planned for new onset AF, start AC as soon as possible
    • Post-cardioversion, must be on anticoagulation for at least 4 weeks d/t atrial stunning and stroke risk
  • CHA2DS2-VASc risk score >2 in M or >3 in F should prompt long term AC in AF persisting >48 hours, even after successful rhythm control
  • DOACs (apixaban, dabigatran, edoxaban, rivaroxaban) are preferred to warfarin except in moderate to severe MS or mechanical valve
  • For apixaban, consider reduced dose 2.5 mg BID if age >80, body weight <60 kg, or serum Cr >1.5 mg/dL
  • 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 (WATCHMAN, Amulet) can be considered in those with increased risk of bleeding, but post-operative oral AC plus aspirin is typically required for 45 days, followed by DAPT for 6 months.
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