Arrhythmias & electrophysiology
Marked QTc Reduction Immediately Following Direct Current Cardioversion of Atrial Fibrillation: Clinical Implications and Mechanisms
Authors' conclusion
In patients with AF following conversion, regardless spontaneous or DCCV, the QTc shortened significantly with decreases in heart rate, likely via the mechanism of time-dependent rate adaption of ventricular repolarization.
Study context
- Population
- Patients with atrial fibrillation (AF) converted to sinus rhythm
- Participants
- 65 patients
- Exposure
- Direct current cardioversion (DCCV) vs spontaneous conversion of AF to sinus rhythm
- DCCVn = 48
- Spontaneous conversionn = 17
- Outcome
- Time-dependent QTc changes (Bazett's and Fridericia's formulas) following conversion
Main finding
As reported in the abstract
Decrease in QTc from QTc in AF, after DCCV · 1 minute post-DCCV
| Group | Value | Bazett's QTc | Fridericia's QTc |
|---|---|---|---|
| DCCV | mean decrease 70.7 (SD 37.2) milliseconds | 70.7 ± 37.2 milliseconds | 33.8 ± 17.9 milliseconds |
DCCV
Valuemean decrease 70.7 (SD 37.2) milliseconds
Bazett's QTc70.7 ± 37.2 milliseconds
Fridericia's QTc33.8 ± 17.9 milliseconds
Observational data: associations, not effects.
Further findings
QTc reduction, spontaneous conversion vs DCCV
- QTc reduction after spontaneous conversion comparable to DCCV
QTc over time after conversion · 5 minutes
- QTc increased with time, reaching steady state at 5 minutes after conversion
Safety
- Initiation of Class III drugs based on the shortened post-DCCV baseline QTc associated with drug-induced torsades de pointes
Original publication
Marked QTc Reduction Immediately Following Direct Current Cardioversion of Atrial Fibrillation: Clinical Implications and Mechanisms. JACC Clin Electrophysiol. Published 18 January 2023. doi:10.
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