Introduction Electrical cardioversion (ECV) is an established therapy for the management of persistent atrial fibrillation (AF). Although ECV is initially successful, recurrence rates of 70–80% have been reported at follow-up at 1 year.1
Fibrillatory waves (Fw) can often been seen on the surface ECG in AF and can be characterised simply and reliably based on their amplitude.2 Amplitudes of ≥0.1 mV are classified as coarse, whilst <0.1 mV are classified as fine (Figure 1). Recent invasive human electrophysiological studies have suggested that AF initiates via organised mechanisms.3 We hypothesised that coarse Fw reflected more ‘early’ organised AF and were therefore a predictor of maintenance of sinus rhythm (SR) after ECV.
Methods We conducted a single centre retrospective observation study by obtaining records of 138 consecutive ECVs. Two cardiologists independently analysed the pre-ECV ECG and classified fine (fFw) or coarse (cFw) F-waves in leads II and V1 using callipers. Follow up was by analysing the 4-week post ECV ECG to assess rhythm. Demographics, drug treatments and echocardiography parameters were analysed as well.
Results From the 138 consecutive ECVs, 8 were excluded due to incomplete datasets, 15 due to atrial flutter being the starting rhythm and 3 due to non-concurrent classification of the Fw by the two cardiologists.
Out of the 112 pre-ECV ECGs, 32% (36/112) had cFw in V1, lead II or both. After ECV, SR was immediately achieved in 95% (106/112) of patients. Overall, of those that were successful, 46% (49/106) were back in AF at the 4-week clinic visit. All patients with cFw had successful initial ECV. At follow-up, 75% (27/36) of patients with cFw on pre-ECV remained in SR compared with 43% (30/70) of patients with fFw who had a successful initial ECV (p = 0.001, Fisher’s exact test).
The cFw and fFw groups were of the similar mean age (70.5 vs. 71.2, p = 0.72). Amiodarone use was similar between groups (8% vs. 17%, p = 0.26) as was left atrial size (4.2 vs. 4.4 cm, p = 0.3); left atrial volume (59 vs. 54 mls, p = 0.5) and indexed left atrial volume (41.8 vs. 39.0 mls/m2, p = 0.34) (Table 1).
Conclusion The presence of coarse Fw in V1, lead II or both resulted in a significantly higher ECV success rate at 4 weeks than fine Fw in both leads. This appeared to be independent of traditional factors thought to affect success. The presence of cFw may be a simple ECG based measure to refine the role of ECV in the treatment of patients with AF.
Lundström T, Rydén L. Chronic atrial fibrillation. Long-term results of direct current conversion. ActaMedScand.1988;223(1):53–59
Xi Q, Swiryn S. Atrial fibrillatory wave characteristics on surface electrogram. J Cardiovasc Electrophysiol. 2004;15(8):911–917
Schricker AA, Narayan SM. Human Atrial Fibrillation Initiates via Organized Rather Than Disorganized Mechanisms. Circ Arrhythm Electrophysiol. 2014;7(5):816–824
- atrial fibrillation
- fibrillatory waves
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