Confirming Anticoagulation Before Cardioversion
Rhythm reversion is deferred until anticoagulation is verified adequate.
- 3 wks: Minimum duration (therapeutic anticoagulation)
- TEE: Alt. pathway (transesophageal echo screen)
- 2–3: Target INR (if on warfarin)
- Yes: DOAC option (direct oral anticoagulants)
Why anticoagulation comes first
Placeholder: cardioversion is delayed until anticoagulation is confirmed adequate.
Placeholder: skipping this step risks dislodging an unseen clot.
Thrombus Formation in the Left Atrial Appendage
Stasis in the fibrillating LAA is the main source of cardioembolic stroke.
- ~90%: Clot source (of AF-related emboli)
- TEE: Detection (gold standard imaging)
- CHA₂DS₂-VASc: Risk score (stroke risk stratification)
- Loss of atrial kick: Stasis cause (during fibrillation)
Why the appendage is high-risk
Placeholder: the LAA is prone to stasis and clot formation during AF.
Placeholder: unrecognized thrombus is the key hazard of early cardioversion.
Synchronized Direct-Current Shock
A synchronized shock depolarizes the atria simultaneously to reset rhythm.
- ~90%: Success rate (immediate reversion)
- R-wave: Synchronization (avoids vulnerable period)
- Required: Sedation (brief procedural sedation)
- 100–200 J: Energy (biphasic waveform)
How the shock restores order
Placeholder: the shock simultaneously resets chaotic atrial cells.
Placeholder: timing to the R-wave avoids inducing ventricular fibrillation.
Antiarrhythmic Drug-Induced Reversion
Antiarrhythmic drugs slow or block the reentrant circuit driving fibrillation.
- ~50–70%: Success rate (lower than electrical)
- Hours: Onset (slower than shock)
- Flecainide: Example agents (class Ic/III drugs)
- No: Sedation needed (unlike electrical method)
How drugs terminate fibrillation
Placeholder: antiarrhythmics interrupt the reentrant electrical circuit.
Placeholder: slower onset means longer monitoring is needed.
Post-Cardioversion Anticoagulation
Anticoagulation continues after cardioversion to cover atrial stunning.
- ≥4 wks: Post-op duration (minimum continuation)
- Atrial stunning: Cause of risk (delayed mechanical recovery)
- Risk-based: Long-term therapy (per CHA₂DS₂-VASc score)
- 0 emboli: Goal (prevent delayed stroke)
Why coverage continues after success
Placeholder: mechanical atrial function lags behind electrical recovery.
Placeholder: stopping anticoagulation too early risks a delayed clot.