Short- and long-term associations of atrial fibrillation catheter ablation with left atrial structure and function: A cardiac magnetic resonance study

Abstract

Background: The effects of atrial fibrillation (AF) catheter ablation on the left atrium (LA) are poorly understood.

Objectives: To examine short- and long-term associations of AF catheter ablation with LA function using cardiac magnetic resonance (CMR).

Methods: Fifty-one AF patients (mean age 56 ± 8 years) underwent CMR at baseline, 1 day (n = 17) and 11 ± 2 months after ablation (n = 38). LA phasic volumes, emptying fractions (LAEF), and longitudinal strain were measured using feature-tracking CMR. LA fibrosis was quantified using late gadolinium enhancement (LGE).

Results: There were no acute changes in volume; however, active, total LAEF, and peak LA strain decreased significantly compared to the baseline. During long-term follow-up, there was a decrease in maximum but not minimum LA volume (from 99 ± 5.2 ml to 89 ± 4.7 ml; p = .009) and a decrease in total LAEF (from 43 ± 1.8% to 39 ± 2.0%; p = .001). In patients with AF recurrence, LA volumes were unchanged. However, total LAEF decreased from 38 ± 3% to 33 ± 3%; p = .015. Patients without AF recurrence had no changes in LA functional parameters during follow-up. The amount of LA LGE at long-term follow-up was higher compared to the baseline, however, was significantly less compared to immediately post-procedure (37 ± 1.9% vs. 47 ± 2.8%; p = .015). A higher increase in LA LGE extent compared to the baseline was associated with a greater decrease in total LAEF (r = -.59; p < .001).

Conclusions: LA function is impaired acutely following AF catheter ablation. However, long-term changes of LA function are associated positively with the successful restoration of sinus rhythm and inversely with increased LA LGE.

Keywords: atrial fibrillation; atrial function; cardiac MRI; catheter ablation; late gadolinium enhancement.

Figure 1.. Left: changes in left atrial (LA) volume during cardiac cycle (ventricular systole and diastole).

Maximum, pre-atrial contraction and minimum LA volumes (points A, B, and C respectively) were measured using the LA volume curve. Right: changes in LA longitudinal strain during the cardiac cycle. Point D indicates peak longitudinal strain.

Figure 2.

CMR images of LA in a patient prior to the catheter ablation (A), immediately post catheter ablation (B), and 8 months after ablation (C). There was a significant increase in LGE from 14% to 36% immediately after the procedure. However, this amount decreased to 21% after 6 months.

Figure 3.

Association of the change in total LA emptying fraction with the change in LA LGE during long-term follow-up. Dashed lines above and below of the gray zone indicate the 95% confidence interval.