Among patients with AF undergoing catheter ablation, atrial tissue fibrosis estimated by delayed enhancement MRI was independently associated with likelihood of recurrent arrhythmia. The clinical implications of this association warrant further investigation.

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.

Objectives This study tried to determine the association between left atrial (LA) fibrosis, detected using delayed-enhanced magnetic resonance imaging (DE-MRI), and the CHADS2 score (point system based on individual clinical risk factors including congestive heart failure, hypertension, age, diabetes, and prior stroke) variables, specifically stroke. Background In patients with atrial fibrillation (AF), conventional markers for the risk of stroke base their higher predictive effect on clinical features, particularly previous stroke history, and not individual LA pathophysiological properties. We aimed to determine the association between LA fibrosis, detected using DE-MRI, and the CHADS2 score variables, specifically stroke. Methods Patients with AF who presented to the AF clinic and received a DE-MRI of the LA were evaluated. Their risk factor profiles, including a CHADS2 score, were catalogued. The degree of LA fibrosis was determined as a percentage of the LA area. Any history of previous strokes, warfarin use, or cerebrovascular disease was recorded. Results A total of 387 patients, having a mean age of 65 ± 12 years, 36.8% female, were included in this study. A history of previous stroke was present in 36 (9.3%) patients. Those patients with previous strokes had a significantly higher percentage of LA fibrosis (24.4 ± 12.4% vs. 16.2 ± 9.9%, p < 0.01). A larger amount of LA fibrosis was also seen in those patients with a higher CHADS2 score (≥2: 18.7 ± 11.4 vs. <2: 14.7 ± 9.2, p < 0.01). A logistic regression analysis of all variables except strokes (CHAD score) demonstrated that LA fibrosis independently predicted cerebrovascular events (p = 0.002) and significantly increased the predictive performance of the score (area under the curve = 0.77). Conclusions Our preliminary, multicenter results suggest DE-MRI–based detection of LA fibrosis is independently associated with prior history of strokes. We propose that the amount of DE-MRI–determined LA fibrosis could represent a marker for stroke and a possible therapeutic target with potential applicability for clinical treatment for patients with AF.

Key PointsQuestionAmong patients with persistent atrial fibrillation (AF), does the addition of magnetic resonance imaging (MRI)-guided fibrosis ablation to conventional catheter ablation affect atrial arrhythmia recurrence?FindingsIn this randomized clinical trial that included 843 patients with persistent AF, there was no significant difference in atrial arrhythmia recurrence in the MRI-guided fibrosis ablation group compared with the pulmonary vein isolation only group (hazard ratio, 0.95).MeaningFindings do not support the use of MRI-guided fibrosis ablation for the treatment of persistent atrial fibrillation.

Introduction Sinus node dysfunction (SND) commonly manifests with atrial arrhythmias alternating with sinus pauses and sinus bradycardia. The underlying process is thought to be because of atrial fibrosis. We assessed the value of atrial fibrosis, quantified using Late Gadolinium Enhanced-MRI (LGE-MRI), in predicting significant SND requiring pacemaker implant. Methods Three hundred forty-four patients with atrial fibrillation (AF) presenting for catheter ablation underwent LGE-MRI. Left atrial (LA) fibrosis was quantified in all patients and right atrial (RA) fibrosis in 134 patients. All patients underwent catheter ablation with pulmonary vein isolation with posterior wall and septal debulking. Patients were followed prospectively for 329 ± 245 days. Ambulatory monitoring was instituted every 3 months. Symptomatic pauses and bradycardia were treated with pacemaker implantation per published guidelines. Results The average patient age was 65 ± 12 years. The average wall fibrosis was 16.7 ± 11.1% in the LA, and 5.3 ± 6.4% in the RA. RA fibrosis was correlated with LA fibrosis (R2 = 0.26; P < 0.01). Patients were divided into 4 stages of LA fibrosis (Utah I: <5%, Utah II: 5–20%, Utah III: 20–35%, Utah IV: >35%). Twenty-two patients (mean atrial fibrosis, 23.9%) required pacemaker implantation during follow-up. Univariate and multivariate analysis identified LA fibrosis stage (OR, 2.2) as a significant predictor for pacemaker implantation with an area under the curve of 0.704. Conclusions In patients with AF presenting for catheter ablation, LGE-MRI quantification of atrial fibrosis demonstrates preferential LA involvement. Significant atrial fibrosis is associated with clinically significant SND requiring pacemaker implantation.

Catheter ablation of AF targeting PVs rarely achieves permanent encircling scar in the intended areas. Overall atrial fibrosis present at baseline and residual fibrosis uncovered by ablation scar are associated with recurrent arrhythmia.

Advancing age and female sex are associated with a higher burden of atrial fibrosis in patients with AF. Women with a prior history of stroke also have higher fibrosis compared with both women and men without history of stroke. Advanced fibrosis may explain the female and age association with stroke in AF.

Introduction Success rates of catheter ablation in persistent atrial fibrillation (AF) remain suboptimal. A better and more targeted ablation strategy is urgently needed to optimize outcomes of AF treatment. We sought to assess the safety and efficacy of targeting atrial fibrosis during ablation of persistent AF patients in improving procedural outcomes. Methods The DECAAF II trial (ClinicalTrials. gov identifier number NCT02529319) is a prospective, randomized, multicenter trial of patients with persistent AF. Patients with persistent AF undergoing a first‐time ablation procedure were randomized in a 1:1 fashion to receive conventional pulmonary vein isolation (PVI) ablation (Group 1) or PVI + fibrosis‐guided ablation (Group 2). Left atrial fibrosis and ablation induced scarring were defined by late gadolinium enhancement magnetic resonance imaging at baseline and at 3–12 months postablation, respectively. The primary endpoint is the recurrence of atrial arrhythmia postablation, including atrial fibrillation, atrial flutter, or atrial tachycardia after the 90‐day postablation blanking period. Patients were followed for a period of 12–18 months with a smartphone ECG Device (ECG Check Device, Cardiac Designs Inc.). With an anticipated enrollment of 900 patients, this study has an 80% power to detect a 26% reduction in the hazard ratio of the primary endpoint. Results and Conclusion The DECAAF II trial is the first prospective, randomized, multicenter trial of patients with persistent AF using imaging defined atrial fibrosis as a treatment target. The trial will help define an optimal approach to catheter ablation of persistent AF, further our understanding of influencers of ablation lesion formation, and refine selection criteria for ablation based on atrial myopathy burden.