Key result
Baseline atrial fibrillation shows no impact on dofetilide discharge dose compared to sinus rhythm.
Why the study?
The optimal timing of cardioversion during dofetilide initiation to optimize discharge dose and the longitudinal stability of QTc remained unknown.
Does baseline rhythm impact discharge dose and longitudinal QTc stability in patients undergoing dofetilide initiation?
Cohort (n=198)
No
Does baseline rhythm impact discharge dose and longitudinal QTc stability in patients undergoing dofetilide initiation?
Dofetilide initiation before cardioversion is equivalent to initiation during sinus rhythm regarding discharge dose, and QTc significantly reduces over time following discharge.
Supports equivalent dofetilide dosing regardless of baseline rhythm; leaves open prospective validation of QTc reduction for monitoring protocols.
Introduction Dofetilide suppresses atrial fibrillation (AF) in a dose‐dependent fashion. The protective effect of AF against QT c prolongation induced torsades de pointe and transient post‐cardioversion QT c prolongation may result in dofetilide under‐dosing during initiation. Thus, the optimal timing of cardioversion for AF patients undergoing dofetilide initiation to optimize discharge dose remains unknown as does the longitudinal stability of QT c . The purpose of this study was to evaluate the impact of baseline rhythm on dofetilide dosing during initiation and assess the longitudinal stability of QT c‐all (Bazzett, Fridericia, Framingham, and Hodges) over time. Methods Medical records of patients who underwent preplanned dofetilide loading at a tertiary care center between January 2016 and 2019 were reviewed. Results A total of 198 patients (66 ± 10 years, 32% female, CHADS 2 ‐Vasc 3 [2–4]) presented for dofetilide loading in either AF (59%) or sinus rhythm (SR) (41%). Neither presenting rhythm, nor spontaneous conversion to SR impacted discharge dose. The cumulative dofetilide dose before cardioversion moderately correlated ( r = .36; p = .0001) with discharge dose. Postcardioversion QT c‐all prolongation ( p < .0001) prompted discharge dose reduction (890 ± 224 mcg vs. 552 ± 199 mcg; p < .0001) in 30% patients. QT c‐all in SR prolonged significantly during loading ( p < .0001). All patients displayed QT c‐all reduction ( p < .0001) from discharge to short‐term (46 [34–65] days) that continued at long‐term (360 [296–414] days) follow‐ups. The extent of QT c‐all reduction over time moderately correlated with discharge QT c‐all ( r = .54–0.65; p < .0001). Conclusion Dofetilide initiation before cardioversion is equivalent to initiation during SR. Significant QT c reduction proportional to discharge QT c is seen over time in all dofetilide‐treated patients. QT c returns to preloading baseline during follow‐up in patients initiated in SR.
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Khan et al. (2022) conducted a cohort in Atrial fibrillation (n=198). Dofetilide vs. Atrial fibrillation vs. sinus rhythm at baseline was evaluated on Discharge dose and longitudinal stability of QTc. Baseline rhythm (atrial fibrillation vs. sinus rhythm) did not impact dofetilide discharge dose, and significant QTc reduction proportional to discharge QTc was observed over time in all patients.
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