Atrial structural remodelling and restoration of atrial contraction after linear ablation for atrial fibrillation.

Abstract

We determined late atrial function following a surgical linear endocardial radiofrequency (RF) ablation procedure that aimed to restore and maintain sinus rhythm (SR) in atrial fibrillation (AF). We tested the hypothesis that successful restoration of SR is accompanied by measurable mechanical atrial function that is at normal or near normal levels. Forty-seven patients who underwent the surgical RF procedure at least 6 months previously (median 2.86 years; range: 0.6-4.2 years) were studied using an array of echocardiographic variables. Two patient groups (SR restored [RF-SR], persistent AF [RF-AF]) and an age matched control group were studied. Among the echocardiographic variables measured were left atrial (LA) size and volume, LA active fractional emptying and mitral annular displacement corresponding to atrial contraction (A' velocity) by Doppler tissue imaging. At long term follow up 29/47of patients who underwent the RF procedure were in SR with atrial contraction present echocardiographically. Of the patients initially restored to SR, the proportion remaining in SR at 3 years was 79% (SE 9%). The atrial-emptying fraction was reduced in comparison to that seen in normal controls (27+/-14% vs 46+/-10%). The A' velocity was decreased in the surgical RF cohort vs controls (4.4+/-1.3 vs 9.7+/-1.7cm/s; P=0.0001). Despite LA size preoperatively being similar in both surgical groups, atrial size decreased in those in whom SR was restored (48.6+/-7.6 vs 44.8+/-4.7mm; P=0.0001) but increased in those in whom AF persisted (48.2+/-8.1mm vs 52.3+/-7.8mm; P=0.0001). The radial pattern of linear radiofrequency ablation used in the present study resulted in restoration of SR and atrial function. Procedural success was independent of preoperative atrial size. Restoration of SR results in 'reverse' atrial remodelling and improved atrial function. However atrial function remains modestly impaired, either due to the ablation lesions or pre-existing atrial disease.