ECG-derived atrial fibrillation organisation index, but not atrial fibrillatory rate, is associated with 30-day recurrence after cardioversion of the first-ever persistent atrial fibrillation episode
T Hagsund, F Holmqvist, B Madsen Hardig, P G PlatonovAbstract
Background
Electrocardiogram-based measures of atrial fibrillation (AF) organisation have been linked to rhythm outcomes after electrical cardioversion. Interpretation is complicated when cohorts include rhythm-control interventions such as ablation and antiarrhythmic drugs that may modify atrial electrophysiology and electrocardiographic characteristics during atrial fibrillation.
Purpose
To evaluate whether atrial fibrillatory rate (AFR) and AF organisation index (spectral exponential decay, ExpD) derived from surface ECG during AF bear prognostic information of early recurrence after cardioversion in first-ever persistent AF episode.
Methods
We conducted a single-centre retrospective cohort study including consecutive patients undergoing electrical cardioversion for first-ever persistent AF episode between February 2019 and October 2022. Inclusion criteria included the lack of class I or class III antiarrhythmic therapy or catheter ablation for AF prior to cardioversion or during follow up. Admission electrocardiograms obtained during AF at the index presentation underwent QRST-cancellation and frequency power spectrum analysis for calculation of AFR and ExpD from the residual atrial signal in lead V1. The endpoint was time to clinically documented atrial fibrillation recurrence within 30 days after cardioversion. We compared the highest quartile (Q4) versus Q1-Q3 using Kaplan-Meier analysis and log-rank tests, and performed Cox regression adjusted for age, sex, and symptom duration to cardioversion.
Results
Among 78 patients (age 68 ± 12 years, 58% male), no patient received rhythm-control antiarrhythmic drug therapy at electrocardiogram acquisition or cardioversion. Thirty patients had AF recurrence within 30 days. The median time from electrocardiogram to cardioversion was 44 days. High ExpD values indicating lower AF signal organisation (Q4) was associated with earlier recurrence (log-rank p=0.02; Figure 1) and remained significant after adjustment (HR 2.42, 95% CI 1.23-4.78; p=0.011). Atrial fibrillatory rate showed no association with recurrence (log-rank p=0.342; Figure 2).
Conclusion
In patients with first-ever persistent AF episodes undergoing electrical cardioversion, low AF organisation, but not the AF frequency estimate, such as AFR, is a prognostic marker of early recurrence in the absence of class I/III antiarrhythmic drug treatment. These findings support further evaluation of exponential decay as a simple, non-invasive measure to risk stratify patients considered for cardioversion with regard to the need of additional rhythm control measures aimed at prevention of AF relapse.