Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: Implications for disease progression and response to catheter ablation

Abstract

BACKGROUND Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease. OBJECTIVE This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities. METHODS Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (≤5% LA wall enhancement), Utah II (>5% to ≤20%), Utah III (>20% to ≤35%), or Utah IV (>35%). RESULTS Distribution in Utah I to IV was comparable in patients with lone AF and non–lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 ± 8.94 vs. 16.94 ± 11.37) was not significantly different between the 2 groups (P = .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non–lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P < .001). CONCLUSION The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.

2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: Recommendations for Patient Selection, Procedural Techniques, Patient Management and Follow-up, Definitions, Endpoints, and Research Trial Design

“…130,560,561 The tissue characterization of the LA wall on DE MRI correlated with EAVM and with histology from surgical biopsy specimens. 560,561 The association of atrial tissue fibrosis and AF catheter ablation outcomes, with more extensive fibrosis associated with lower efficacy, was confirmed in the multicenter Delayed Enhancement MRI and Atrial Fibrillation Catheter Ablation (DECAAF) study.…”

“…The question of whether atrial fibrosis stems from AF itself, from AF-related risk factors, or from a specific fibrotic atrial cardiomyopathy (FACM) is under debate. 130,131,132,133,134 Recently, a subgroup of patients with recent onset persistent AF have been described with a diffuse abnormal substrate and with poor outcome after ablation. 135 There is great variability in the amount of fibrosis in patients with AF, in which some patients with PAF have massive fibrosis and some patients with persistent AF show mild fibrosis.…”

“…140 Similarly, cardiovascular risk factors were found to be equally distributed in various classes of LA fibrosis as described by MRI studies, and structural atrial remodeling was the same in patients with and without cardiovascular risk factors. 130 On the other hand, there is extensive evidence that many AF risk factors do substantially increase atrial fibrosis content, and that AF itself might have a profibrotic effect. 141,142,143 One study reported that elevated serum markers of collagen synthesis were associated with postsurgical AF, compared with those who stayed in sinus rhythm.…”

EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication

“…Late-gadolinium-enhanced CMR has also been used to predict development of sinus node dysfunction, 417 stroke risk, 418 and progression of atrial fibrillation from paroxysmal to persistent. 419 However, various studies have highlighted the need to further improve the methods of accurately identifying replacement fibrosis and to improve reproducibility of data analysis before LGE CMR can be considered a routine clinical tool. 420,421 Recently, a number of studies have used CMR DE late gadolinium enhancement (LGE) in order to non-invasively characterize the extent and distribution of scarring present following AF ablation.…”

Catheter Ablation of Lone Atrial Fibrillation

“…Several months later he was subjected to catheter ablation of AF, due to the clinical suspicion of tachyarrhythmia-related cardiomyopathy. obesity, biochemical markers of inflammation, atrial fibrosis on MRI and increased CHADS 2 and CHA 2 DS 2 -VAS C score [18,74,[80][81][82][83][84]. Therefore, among younger patients with lone AF and normal or minimally remodelled LA, not only higher efficiency but also more stable long term effects of catheter ablation can be expected.…”