Outcome of pulmonary vein isolation ablation for paroxysmal atrial fibrillation: predictive role of left atrial mechanical dyssynchrony by speckle tracking echocardiography.

INTRODUCTION: Although few clinical variables have been associated with recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) the role of left atrial (LA) mechanical function in the outcome of catheter ablation of AF is not adequately defined. The aim of our study was to determine whether LA mechanical dyssynchrony as evaluated by speckle tracking echocardiography can predict outcome of PVI ablation procedure in patients with paroxysmal AF.
METHODS: Twenty-five patients (age 58 ± 11 years, [mean ± standard deviation], 17 males) with paroxysmal AF who met specific enrollment criteria pertaining to clinical presentation and follow-up, assessment of LA mechanical dyssynchrony, and strategy of catheter ablation procedure were enrolled. For LA mechanical dyssynchrony assessment, the time to peak longitudinal strain (TPk) in opposing walls in the midportion of the LA walls at peak atrial contraction in standard two- and four-chamber echocardiographic views by vector velocity imaging (VVI) was measured. Outcome of PVI procedure, whether no recurrence (NR) or AF recurrence (AFR) after 3 months of post-procedural blanking period, was evaluated based on AF-related symptoms and documentation of AF by electrocardiogram, continuous 24-h Holter, and intermittent event monitor recordings.
RESULTS: During a follow-up period of 20.3 ± 8.6 months, 18 out of 25 (72 %) patients had no recurrence (NR group), and 7 out of 25 (28 %) patients had recurrence of AF (AFR group). Significant gender difference was observed in terms of outcome such that all AFR patients were men and no woman had recurrence of AF. Between the NR and AFR groups, neither the left atrial diameter, 4.0 ± 0.3 and 4.2 ± 0.2 cm, respectively (p = 0.2), nor the left atrial volume indexes, 45 ± 15 and 48 ± 20 ml/m(2), respectively (p = 0.56), were statistically significantly different. For LA mechanical function, compared to the patients in NR group who had maximum opposing wall TPk delay of 39.9 ± 12.0 ms, those in the AFR group demonstrated significantly more LA mechanical dyssynchrony with maximum opposing wall TPk delay of 64.4 ± 17.0 ms prior to ablation (p = 0.007). Using receiver operative characteristic analyses of the data that had an area under the curve of 0.865, we identified a maximum opposing wall delay cutoff value of 51 ms which predicted AF recurrence with sensitivity and specificity values of 89 and 72 %, respectively (p = 0.005).
CONCLUSIONS: Speckle tracking strain analysis echocardiography can evaluate the LA mechanical dyssynchrony quantitatively. The severity of LA mechanical dyssynchrony by VVI can predict the outcome of PVI catheter ablation for paroxysmal AF.