Background:

For patients with symptomatic, drug-refractory atrial fibrillation (AF) catheter ablation to achieve rhythm control is an important therapy option. However, recurrence following ablation therapy is still high and variables to identify patients with a high rate of success are thus warranted. The atrial mechanical dispersion measured as standard deviation of the time to peak strain (SD-TPS) could be a marker of developing atrial cardiomyopathy and associated with the risk of AF recurrence following catheter ablation.

Purpose:

Assessing the risk of recurrence of AF in patients presenting for de novo AF ablation with paroxysmal or persistent atrial fibrillation using different imaging variables with the focus of the left atrium and clinical variables including age, sex, type of AF and left atrial volume indexed to BSA (LAVI) in conjunction with the variable with the best association to AF recurrence risk of the imaging variables. Recurrence of AF was assessed after a time-period of 1 year.


Methods:

The ASTRA-AF pilot study prospectively enrolled n=132 consecutive patients with paroxysmal or persistent AF presenting for de novo pulmonary vein isolation (PVI). A baseline transthoracic echocardiography was performed in every patient prior to PVI. Imaging variables were analyzed with post processing software (IMAGE-COM, TOMTEC-ARENA, Tomtec Imaging System GmbH). Patients with atrial fibrillation at presentation, poor 2D imaging quality or impaired left ventricular ejection fraction <50% were excluded. All analysis were censored after a median follow-up time of 1 year. LA mechanical dispersion was defined as the standard deviation of time to peak positive strain (SD-TPS) from the 3 LA segments used by the software.

Cox regression models were calculated in an uni- und multivariable approach for a model including the imaging variables global longitudinal strain of the left ventricle, LAVI, left atrial ejection fraction and SD-TPS and clinical variables including sex, age, type of AF, left atrial volume indexed to BSA.

Results:

The cohort of patients included 132 patients with either paroxysmal AF (n=88) or persistent AF (n=44). The median age of the cohort was 66 years (95% CI, 55;73) and 59,8% were male (n=79). Recurrence rate of AF after a time period of 1 year was 24.1%. The assessed imaging variables included the left atrial volume indexed to BSA with 29,6ml/m² (95% CI, 22.9;35.7ml/m²) and new parameters like left atrial ejection fraction with 40.6% (95% CI, 31.9;49.7%), global longitudinal strain of the left ventricle -19.6 (95% CI,-22.1,-17.8%) and SD-TPS with 33.9msec (95% CI, 16.3;56.0msec). The variable with the best association with AF recurrence in the multivariable Cox regression of the imaging variables was SD-TPS with a HR 1.01 (95% CI,1.00;1.01,p=0.03) per unit increase (Figure 1 A+C). Due to these results SD-TPS was as well included into the analysis with the clinical variables with a HR of 1.00 (95% CI,1.00;1.01,p=0.09) per unit increase in multivariable analysis (Figure 1 B+D).

Conclusion:

In the ASTRA-AF pilot study assessing the risk of AF recurrence during 1 year follow-up with imaging variables and validated clinical variables, atrial mechanical dispersion was associated with the outcome of AF recurrence regarding the assessed imaging variables. Increased atrial mechanical dispersion might be an indicator of AF recurrence following catheter ablation.

Figure 1