Atrial Fibrillation & Flutter

Michael Daw

Background

  • AF: 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).

Stages of AF

  • Stage 1 (at risk): Presence of modifiable and non-modifiable risk factors.
  • Stage 2 (pre-AF): Evidence of structural or electrical findings that predispose to AF (ex. Atrial enlargement).
  • Stage 3 (AF spectrum)
  • Paroxysmal AF (3a): intermittent AF and terminates <7 days.
  • Persistent AF (3b): continuous >7 days.
  • Long-standing persistent (3c): continuous for >12 months.
  • Successful AF ablation (3d): s/p intervention to eliminate AF.
  • Stage 4 (Permanent AF): 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
  • Initial workup: EKG, TTE, CXR, TFTs, BMP, hepatic function panel, CBC, NT-proBNP.
  • Consider longer term monitoring with Zio patch, Holter monitoring.

Management

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

Rate Control

  • Unless unstable, 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 (start with 150J)
    • 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.
  • 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.
  • Beta blockers: Start with metoprolol tartrate (titratable) à consolidate to succinate. Avoid in decompensated HF (class 2b rec for IV amio, per guidelines).
  • Calcium channel blockers (diltiazem): DO NOT give in HFrEF.
  • 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).

Cardioversion

  • Synchronized electrical cardioversion (DCCV).
  • Pharmacologic cardioversion options include class 1C: flecainide, propafenone (avoid in structural heart disease) and class 3: Amiodarone, dronedarone, sotalol, ibutilide, dofetilide (some require inpatient loading on telemetry/cardiac SDU).

Anticoagulation

  • Pre-cardioversion: if onset clearly within 48h or patient has been on AC for >3 weeks uninterrupted, can proceed without TEE. If onset >48h or unclear, will need TEE to rule out LAA thrombus; you can also anti-coagulate for 3 weeks prior to TEE if unable to get TEE.
  • Post-cardioversion: must be on anticoagulation for at least 4 weeks d/t atrial stunning and stroke risk. Decision for AC after 4-weeks should be based of HASBLED and CHA2DS2-VASc score.
  • Consider EP consult for ablation in symptomatic paroxysmal or persistent AF refractory to antiarrhythmic drugs, AF in HFrEF, or flutter in outpatient setting.

Stroke Prevention (for AF and Flutter)

  • If cardioversion is planned for new onset AF, start AC as soon as possible
  • 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, mechanical valve, or HOCM.
  • For apixaban, consider reduced dose 2.5 mg BID if age >80, body weight <60 kg, or serum Cr >1.5 mg/dL.
  • 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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