Association of Postprocedural Left Atrial Volume and Reservoir Function with Outcomes in Patients with Atrial Fibrillation Undergoing Catheter Ablation

Background: The value of left atrial (LA) volume and reservoir function (ResF) after ablation for atrial fibrillation for predicting overall outcomes needs further investigation, particularly in large cohorts. The aim of this study was to test the hypothesis that abnormal LA volume and ResF after ablation are associated with adverse outcomes.

Methods: Patients who underwent primary atrial fibrillation ablation between 2007 and 2016 and had available measurements of maximum LA volume index (LAVImax) and minimum LA volume index (LAVImin) and LA ResF (LA emptying fraction and LA expansion index) at 3-month echocardiographic examination after ablation were included in this analysis. The primary endpoint was the composite of cardiac hospitalization for heart failure or acute ischemic events, stroke or transient ischemic attack, and all-cause death; secondary endpoints were cardiac hospitalization and all-cause death.

Results: A total of 792 patients were studied (mean age, 60 ± 10 years). Over a median of 7.5 years (interquartile range, 3.0-9.7 years) of follow-up, 96 patients experienced adverse events. After adjustment for several parameters, including age, comorbidities, and left ventricular structure and function, increased LA volumes and impaired ResF were each independently associated with the primary endpoint (LAVImax > 34 mL/m²: adjusted hazard ratio [HR], 2.37 [95% CI, 1.49-3.76; P = .0003]; LAVImin ≥ 20.5 mL/m²: adjusted HR, 3.21 [95% CI, 1.97-5.24; P < .0001]; LA emptying fraction < 40%: adjusted HR, 2.00 [95% CI, 1.29-3.10; P = .002]; LA expansion index < 66%: adjusted HR, 1.91 [95% CI, 1.22-2.98; P = .005]) as well as with the secondary endpoints of cardiac hospitalization (P < .05 for adjusted HR for all LA parameters) and all-cause death (P < .05 for adjusted HR for LAVImin, LA emptying fraction and LA expansion index). ResF measures were incremental to LAVImax (P < .05 for all), but not to LAVImin. In patients with normal LA (LAVImax ≤ 34 mL/m²; n = 403), those with higher LAVImin (≥17 mL/m²) were at 4 times higher risk for primary endpoint events (age-adjusted HR, 4.32; 95% CI, 1.90-9.81; P = .0005). All these findings were independent of atrial tachyarrhythmia recurrence.

Conclusions: Enlarged left atrium and impaired ResF at 3 months after ablation for atrial fibrillation are strongly associated with long-term outcomes, independent of left ventricular function or cardiac rhythm at follow-up. LAVImin showed the strongest associations and even identified a high-risk subgroup among patients with nondilated left atria.