In a prospective study utilizing advanced echocardiographic assessments, we have demonstrated the following findings: (1) Atrial mechanical dispersion, as indicated by SD-TPS, is associated with an elevated risk of AF recurrence. (2) On the other hand, left atrial volume index (LAVI) was not associated with the risk of AF recurrence. (3) By establishing a cut-off value of 38.6 ms for SD-TPS, it may be possible to identify patients who are at a higher risk of experiencing AF recurrence. (4) Following catheter ablation using either radiofrequency or cryoballoon techniques, the rate of AF recurrence after 1 year of follow-up was relatively low at 23%. (5) Through multivariable analysis, we determined that age is the most significant clinical variable in terms of the risk of AF recurrence.

Left atrial structure and risk of AF recurrence

The concept of LV mechanical dispersion assumes that tissue alterations and as a consequence different conduction times can be measured with the timing of the peak strain values, and that increases in the standard deviation of LV mechanical dispersion correlate with the presence of arrhythmias [10]. Further underlining the additional value of measuring SD-TPS in the LA is the previous finding that intra-atrial dyssynchrony during sinus rhythm is associated with an increased risk of AF recurrence following catheter ablation [11]. In our study, in patients both without and with recurrence of AF, mean LAVI was not above the threshold of 34 mL/m2, which is often related to diastolic dysfunction, while further increased LA volumes of the LA have long been known to facilitate new episodes of AF and recurrence following a therapeutic intervention [6, 7, 15]. Despite the finding of normal mean LAVIs in the study population, SD-TPS values were higher in patients with AF recurrence in the first year following catheter ablation, suggesting changes of the atrial tissue resulting in a conduction delay which might be a characteristic of developing or present atrial cardiomyopathy [20]. A previous study demonstrated as well that SD-TPS is a marker for recurrence of AF following catheter ablation [21]. However, this study only included patients with PAF, and catheter ablation was performed with radiofrequency ablation in all patients [21]; thus, the presented study more accurately represents a real-world population presenting for catheter ablation [1]. The calculated cut-off value for SD-TPS of 38.6 ms is close to the previously published mean SD-TPS of 38 ms in patients with AF recurrence [21]; however, the cut-off originating from our cohort is data-driven and thus cannot be recommended for general use. The results show that even in a cohort including PAF and PersAF with normal LAVI SD-TPS can be applied to detect changes of the atrial tissue facilitating AF recurrence in terms of prolongation of the SD-TPS [12, 21].

Imaging variables and recurrence of AF following PVI

In the study, additional imaging variables were assessed as well, including LV global longitudinal strain (LV-GLS), which was reported to be associated with the presence of AF in patients with cryptogenic stroke [22]. However, despite different mean values in the group of patients with and without AF recurrence, LV-GLS was not associated with the risk of AF recurrence in the multivariable analysis. Regarding the LV-GLS with the suggested cut-off from our analysis of − 22.2%, this value is more negative than the suggested − 20% for a healthy individual, which might not reflect the comorbidities of most of the patients [16, 22]. This might add to the finding that functions of the LV and LA have a close relation with influence of the hemodynamic status of the LV on the LA, thus facilitating AF recurrence. The suggested LA ejection fraction is a parameter which is calculated according to the formula as equivalent to the LV ejection fraction [16] and is termed total emptying fraction [23], reflecting the global function of the LA with a reservoir, conduit, and booster pump, and thus might be an indicator of a poor outcome in AF patients. Our study calculated LA ejection fraction with a cut-off of 35.7% lower than the suggested threshold in the literature; however, this might be due to a diversity of the study cohorts; the values were derived from [15]. Left atrial ejection fraction showed a different distribution between patients with and without AF recurrence and lower values in patients with AF recurrence, indicating a reduced total emptying fraction in this group of patients which might as well indicate a decreased function of the LA. However, in multivariable analysis, only SD-TPS was identified as the imaging variable associated with AF recurrence.

Clinical variables and recurrence of AF following catheter ablation

The variables with the highest predictive value regarding the development of AF are age and sex [1, 2], which have been well studied in different projects researching recurrence of AF following catheter ablation [13]. It is furthermore well established that the type of AF (paroxysmal vs. persistent), reflecting alterations of the atrial myocardial tissue, affects AF recurrence [13, 20].

Appraisal of the combined approach of combining imaging and clinical variables

The major benefit of combining imaging variables and clinical variables to predict risk of AF recurrence following treatment with catheter ablation is the high availability of data, as echocardiographic parameters are guideline-recommended with class I according to the current guidelines in AF patients [1]. The clinical variables age, sex, and type of AF are routinely collected and available in all patients. Additional suggestions like the inclusion of biomarkers in these models might as well refine the risk assessment of AF recurrence but demand additional resources of the health care system and might thus not be as broadly available [13]. In the multivariable analysis including the clinical variables and SD-TPS, only age remained a predictor of AF recurrence. However, as age is a non-influenceable factor in the treatment of AF, SD-TPS might be a novel diagnostic tool to facilitate treatment decision in AF patients.

Although in current guidelines and in literature LAVI is the preferred imaging variable used for risk stratification regarding development of AF and for treatment decisions, our study demonstrates that consideration of additional imaging variables like atrial mechanical dispersion parameters might be worthwhile in an integrated approach including clinical variables to assess the risk of AF recurrence following catheter ablation.

Defining variables that are reliable for identifying patients at high risk of developing AF following catheter ablation might have implications for increasing screening for AF recurrence [24].

Strengths and limitations

The major strength of the presented study is that it reflects a real-world cohort of AF patients presenting for the first PVI using state-of-the-art diagnostic and treatment methods with both radiofrequency and cryoballoon ablation. This sets it apart from previous studies as it encompasses patients with both paroxysmal and persisting AF who were candidates for catheter ablation. Additionally, the echocardiographic assessments were conducted by experienced physicians in a large tertiary center. However, it is important to note that the study’s limitations include its single-center nature and small sample size, which necessitates validation of the data-driven results in larger study cohorts. Furthermore, the assessment of SD-TPS requires expertise in interpretation, which may limit its use in general settings.