• atrial fibrillation
• transcatheter ablation
• left atrium
• tissue Doppler Imaging
• PA-TDI

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is associated with significant morbidity and overall mortality. Pulmonary vein isolation (PVI) is a well-established treatment in patients with AF who do not respond to or tolerate antiarrhythmic drug therapy. Despite technical and medical advances in ablation therapy, the prediction of a patient risk of recurrence remains challenging. Therefore, optimal patient selection based on preprocedural screening for risk factors could contribute to improve individual outcomes.
Structural atrial remodeling has been associated with the maintenance sinus rhythm and the risk of recurrence of AF, so several imaging techniques and measures of both atrial structure and function have been investigated. The maximum volume of the left atrium has already been validated as a marker for the development of AF in several studies or its recurrence; notwithstanding, atrial dimension cannot explain all the arrhythmic recurrences. Recently, a novel echocardiographic parameter derived from tissue Doppler imaging (TDI), called PA-TDI, has been introduced to assess the electro-mechanical interval, as a non-invasive surrogate of fibrosis and remodeling.
This study aimed to investigate whether PA-TDI can be used to predict the recurrence of AF in patients who underwent transcatheter ablation procedure.

METHODS
We prospectively included patients with paroxysmal or persistent symptomatic drug-refractory AF referred to our Institution for catheter ablation procedure. A complete transthoracic echocardiogram was performed before and the day after the ablation procedure, including the assessment of PA-TDI interval.

RESULTS
From October 2018 to May 2020, 221 patients (mean age 61 ± 9 years, 74% male, BMI 26.5 ± 4.1 kg/m2, LVEF 61 ± 6%) with symptomatic drug refractory AF who received radiofrequency or cryoballoon catheter ablation were enrolled. Out of the blanking period, 25% of patients experienced recurrence of arrhythmia during the follow-up (mean 16 months). Compared to patients who did not relapse, patients with AF recurrence have a generally longer post-procedural PA-TDI interval (139.6 ± 22.1 msec vs 153.9 ± 33 msec, respectively). In the multivariable analysis only post-procedure PA-TDI and re-do interventions were found to be independent predictors of AF recurrence. A PA-TDI cut-off > 144 msec identifies patients at risk of post ablation AF recurrence with sensitivity 58.7% and specificity 73.5 % (AUC 0.697).

CONCLUSION
The total activation time assessed by PA-TDI interval is an independent predictor of AF recurrence after catheter ablation. This echocardiographic parameter is easily achievable, low-cost, and reproducible.