Cardiac Remodeling After Atrial Fibrillation Ablation

Abstract

Radiofrequency catheter ablation procedures are considered a reasonable option for patients with symptomatic, drug refractory atrial fibrillation (AF). Ablation procedures have been reported to effectively restore sinus rhythm and provide long-term relief of symptoms. Both electrical and structural remodeling occurs with AF. A reversal of the electrical remodeling develops within 1 week after restoration to sinus rhythm following the catheter ablation. The recovery rate is faster in the right atrium than the left atrium. Reverse structural remodeling takes longer and is still present 2 to 4 months after restoration of sinus rhythm. The left atrial transport function also improves after successful catheter ablation of AF. Left atrial strain surveys from echocardiography are able to identify patients who respond to catheter ablation with significant reverse remodeling after ablation. Pre-procedural delayed enhancement magnetic resonance imaging is also able to determine the degree of atrial fibrosis and is another tool to predict the reverse remodeling after ablation. The remodeling process is complex if recurrence develops after ablation. Recent evidence shows that a combined reverse electrical and structural remodeling occurs after ablation of chronic AF when recurrence is paroxysmal AF. Progressive electrical remodeling without any structural remodeling develops in those with recurrence involving chronic AF. Whether progressive atrial remodeling is the cause or consequence during the recurrence of AF remains obscure and requires further study.

Figure 1.. Electroanatomic bipolar voltage mapping in a patient with paroxysmal AF undergoing an initial catheter ablation and a repeat ablation of AF which recurred as paroxysmal AF

Panels A and B denote the right anterior oblique view of the left atrium in the first and second procedures. The color annotation shows a range of colors with a bipolar voltage of ≤0.5 mV shown in gray, all the way through to a voltage of > 2.0 mV shown in purple. During the second procedure (B), a newly developed low voltage zone occurred over the mid-to-lower anterior wall of the left atrium and right superior pulmonary vein antrum of the left atrium, and the high voltage area shown in purple decreased. LAA: left atrial appendage, MV: mitral annulus. (Reproduced with permission from Lo LW, et al. J Cardiovasc Electrophysiol 2007;18:258-265.[23])

Figure 2.. Electroanatomic bipolar voltage maps in patients with chronic AF undergoing catheter ablation in which one recurred as paroxysmal AF (A), and the other as persistent AF (B). Both panels represent the anterioposterior view of the left atrium in the first and second procedures

The color annotation is the same as in Figure 1. In Panel A, there is a decrease in the low voltage area and an increase in the high voltage areas noted in the second procedure. In Panel B, a progressive electrical remodeling with an increase in the low voltage areas is noted in the second procedure. (Reproduced with permission from Lo LW, et al. J Cardiovasc Electrophysiol 2011;22:385-393.[24])

Figure 3.. Wall motion analysis with a Bull's-eye plot showing examples without (A) and with (B) recurrences after the AF ablation

The purple dots represent the end-diastolic left atrium and white dots the end-systolic left atrium. In the Bull's-eye figures, the blue parts indicate the areas with minimal wall motion (~1-3 mm) and the red parts indicate the areas with greater wall motion (~12-15 mm). There is a decreased wall motion of the anterior roof (segment 1,2,3), and an increased wall motion of the rest of the left atrium can be demonstrated in the patient without recurrence (Panel A). In Panel B, the wall motion and volume of the left atrium were similar before and after the ablation because a recurrence occurred in this patient. (Reproduced with permission from Tsao HM et al. J Cardiovasc Electrophysiol 2010;21:270-277.[27])