A Long Atrial Electromechanical Interval is Associated with Arrhythmic Recurrence after Catheter Ablation: How to Find What Has Been Lost

Abstract

Background: Atrial fibrillation (AF) results in electrical and structural remodeling of the atria, which extent is known to be associated with a higher AF recurrence rate after catheter ablation (CA). Recently, a novel echocardiographic parameter derived from tissue Doppler imaging (TDI) [PA-TDI] has been introduced to assess the total atrial activation time, as a noninvasive surrogate of fibrosis and remodeling. The aim of the study is to investigate the role of PA-TDI interval as a predictor of AF ablation efficacy.

Methods: We retrospectively included patients with paroxysmal symptomatic drug-refractory AF referred to our institution for CA procedure, who presented sinus rhythm at admission. A complete transthoracic echocardiogram was performed before the ablation procedure, including the assessment of PA-TDI interval.

Results: From January 2015 to April 2018, 128 patients (mean age: 61.86 ± 9.08 years, 68% male, body surface area: 1.97 ± 0.21 mq, body mass index: 26.98 ± 3.86 kg/mq, and ejection fraction: 59% ±6.06%) with symptomatic drug-refractory AF who received radiofrequency CA were enrolled. During the follow-up of 15.80 ± 6.7 months, 30 patients (23%) developed AF recurrence out of the blanking period. Compared with those without recurrence (group 1), patients with recurrence (group 2) had a larger left atrium (LA) size (Group 1 vs. Group 2: mean LA area: 22.2 ± 4.6 cmq vs. 25 ± 6.6 cmq, P = 0.015; mean indexed LA volume: 35 ± 10 mL/mq vs. 40 ± 12 mL/mq, P = 0.04) and longer PA-TDI interval (Group 1 vs. Group 2: 162 ± 33 ms vs. 133 ± 26 ms, P < 0.0001). A cutoff of PA-TDI > 150 ms identified patients with recurrence after ablation with a sensibility of 82% and specificity of 83% (area under the curve 0.879).

Conclusions: The total activation time assessed by PA-TDI is an independent predictor of AF recurrence and can be used to predict the efficacy of transcatheter ablation.

Keywords: Atrial fibrillation; PA-TDI; left atrium; tissue Doppler imaging; transcatheter ablation.

Figure 1

Example of measurement of PA-TDI duration with color-coded tissue Doppler imaging image. A fixed pixel region of interest was placed on the left atrium lateral wall just above the mitral annulus, deriving a velocity curve of the segment. The PA-TDI duration is assessed by measuring the time interval between the onset of the P-wave of the surface ECG and the peak A’-wave on the tissue Doppler tracing. 2D = Two-dimensional, TDI = Tissue Doppler imaging, PW = Pulsed-wave Doppler

Figure 2

Box plots showing the mean difference in PA-TDI interval time duration between patients with atrial fibrillation recurrence and patients in sinus rhythm during follow-up. TDI = Tissue Doppler imaging, AF = Atrial fibrillation, SR = Sinus rhythm

Figure 3

Receiver operator characteristic curve analyses of the total atrial conduction time (PA-TDI duration) and left atrial area according to the recurrence of atrial fibrillation during follow-up, showing higher area under the curve, thus higher discriminative power of PA-TDI when compared to left atrial area. TDI = Tissue Doppler imaging. LA = Left atrium, ROC = Receiver operator characteristics

Figure 4

Kaplan–Meier curve for freedom of atrial fibrillation, dividing the population into two groups based on a cutoff of PA-TDI duration of 150 ms, excluding a 90-day blanking period. Curves show significant differences between groups based on PTA-DI higher or lower than 150 ms (P < 0.01) TDI = Tissue Doppler imaging