The effects of early recurrence of atrial fibrillation on left atrial remodeling after pulmonary vein isolation - A cardiac magnetic resonance study

Pulmonary vein isolation (PVI) using radiofrequency (RF) ablation is an established treatment for atrial fibrillation (AF). Although successful restoration of sinus rhythm after PVI is known to ultimately result in left atrial (LA) reverse remodeling, little is known about the impact of PVI on the dynamic progression of LA volumes and function during the blanking period, especially in the context of early AF recurrence.

To assess LA volumetric and functional remodeling parameters using CMR early (<72h) and later (3 months) after PVI in patients with and without early AF recurrence.

This study involved 44 patients (61±8 years, 72.7% male, 68.2% paroxysmal AF) undergoing RF pulmonary vein isolation (PVI). CMR scans were performed before the PVI procedure, <72 hours post-PVI, and repeated 3 months post-PVI. LA volumes and strain were assessed using two- and four-chamber cine images (Circle CVI, Calgary, Canada). Minimum and maximum LA volumes were indexed to body surface area to compute LAVImin and LAVImax, respectively. Longitudinal LA strain was analyzed through the feature tracking model, subdivided into reservoir, conduit, and contractile strain. AF, atrial flutter, or atrial tachycardia episodes, detected either through 24h Holter monitoring and ECG or Kardia recordings, were considered early AF recurrence during the blanking period of 90 days post-ablation.

LA volumes significantly decreased at 3 months post-PVI (Figure 1). Early post-PVI, LA function, as measured by LA emptying fraction (LA EF), LA reservoir, and LA contractile strain, showed significant reductions (52.5±11.1% to 48.1±7.9%, p=0.02; 18.1±4.5% to 15.2±2.4%, p<0.001; 8.3±3.1% to 5.3±1.7%, p<0.001, respectively). At 3 months, LA reservoir and contractile strain partially recovered, although LA contractile strain remained significantly lower than baseline (8.3±3.1% to 6.7±2.3%,p<0.01).

Arrhythmia recurrence in the 90-days blanking period was observed in 13 of the 44 patient (29.5%). Notably, LAVImax reduced at 3 months in both groups, while LAVImin did not significantly decrease in the early AF recurrence group (Figure 2). Patients without early AF recurrence, exhibited improved LA function at 3 months as compared to early post-PVI, indicated by increased LA reservoir (15.3±2.5% to 17.1±3.1%, p=0.01) and LA contractile strain (5.3±1.8% to 6.7±2.4%, p<0.01), which was not observed in patients with early AF recurrence (Figure 2).

LA volumes significantly reduced 3 months post-PVI, indicating reversed atrial remodeling. While LA function initially declined, it showed partial recovery at 3 months, as LA contractile strain did not recover to pre-PVI levels. LA reverse remodeling occurred in patients regardless of early AF recurrence, however, recovery of LA function was only observed in those without early AF recurrence.

LA remodeling post-PVI