What is the clinical evidence from this study?

Study design: Observational. Population: Atrial fibrillation (n=37). Intervention: Nonenhancing (NE) regions on late gadolinium enhancement MRI immediately post-ablation vs. Hyperenhancing (HE) and normal tissue. Primary outcome: Proportion of permanent scar at 3 months post-ablation resulting from specific tissue types (p=<0.001).

What does this research mean for the field?

Nonenhancing (no-reflow) lesions on MRI immediately post-ablation are the primary source of permanent scar formation at 3 months, accounting for 59.0% of scar tissue compared to 30.6% from hyperenhancing tissue. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

June 4, 2026Open Access

Dark Regions of No-Reflow on Late Gadolinium Enhancement Magnetic Resonance Imaging Result in Scar Formation After Atrial Fibrillation Ablation

Q: What are the key findings of this study?

Nonenhancing (no-reflow) lesions on MRI immediately post-ablation were the primary source of permanent scar at 3 months (59.0% vs 30.6% for hyperenhancing tissue, p<0.001).

Q: What does this research mean for the field?

Nonenhancing (no-reflow) lesions on MRI immediately post-ablation are the primary source of permanent scar formation at 3 months, accounting for 59.0% of scar tissue compared to 30.6% from hyperenhancing tissue. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Q: What question did this study set out to answer?

The study aims to evaluate the association between acute ablation injuries seen on late gadolinium enhancement MRI and permanent scar formation at three months post-ablation.

Key Result

Nonenhancing (no-reflow) lesions on MRI immediately post-ablation were the primary source of permanent scar at 3 months (59.0% vs 30.6% for hyperenhancing tissue, p<0.001).

Key Points

The study aims to evaluate the association between acute ablation injuries seen on late gadolinium enhancement MRI and permanent scar formation at three months post-ablation.
Thirty-seven patients underwent high-resolution MRI pre-ablation, post-ablation, and at three months post-ablation using a 3-T scanner.
Ablation injuries were categorized as hyperenhancing or nonenhancing, with comparisons made to scarring at three months post-ablation.
Data on tissue types and scarring were analyzed for statistical significance.
59.0 ± 19% of scar at three months resulted from nonenhancing tissue, while 30.6 ± 15% came from hyperenhancing tissue.
Changes in left atrial wall showed HE, NE, and normal tissue percentages were 37.7 ± 13%, 34.3 ± 14%, and 28.0 ± 11%, respectively; p = NS.
Arrhythmia recurrence at 1-year follow-up correlated with 3-month wall enhancement degree (p = 0.02).

Study Design

Type

Observational (n=37)

Structured PICO

Do nonenhancing (NE) regions on LGE MRI immediately post-ablation better predict permanent scar formation at 3 months compared to hyperenhancing (HE) regions in patients undergoing atrial fibrillation ablation?

Population

37 patients presenting for atrial fibrillation ablation who underwent high-resolution MRI before, immediately post, and 3 months post-ablation.

Exposure

Radiofrequency ablation followed by high-resolution 3-T late gadolinium enhancement (LGE) MRI immediately post-ablation

Comparator

Comparison of hyperenhancing (HE) versus nonenhancing (NE) acute left atrial wall injuries on immediately post-ablation MRI

Outcome

Permanent scar formation at 3 months post-ablationsurrogate

Nonenhancing 'no-reflow' lesions on LGE MRI immediately post-ablation are significantly better predictors of permanent scar formation at 3 months than hyperenhancing lesions.

Main Result

Absolute Event Rate: 59% vs 30.6%

p-value: p=<0.001

Abstract

Objectives The aim of this study was to assess acute ablation injuries seen on late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) immediately post-ablation (IPA) and the association with permanent scar 3 months post-ablation (3moPA). Background Success rates for atrial fibrillation catheter ablation vary significantly, in part because of limited information about the location, extent, and permanence of ablation injury at the time of procedure. Although the amount of scar on LGE MRI months after ablation correlates with procedure outcomes, early imaging predictors of scar remain elusive. Methods Thirty-seven patients presenting for atrial fibrillation ablation underwent high-resolution MRI with a 3-dimensional LGE sequence before ablation, IPA, and 3moPA using a 3-T scanner. The acute left atrial wall injuries on IPA scans were categorized as hyperenhancing (HE) or nonenhancing (NE) and compared with scar 3moPA. Results Heterogeneous injuries with HE and NE regions were identified in all patients. Dark NE regions in the left atrial wall on LGE MRI demonstrate findings similar to the “no-reflow” phenomenon. Although the left atrial wall showed similar amounts of HE, NE, and normal tissue IPA (37.7 ± 13%, 34.3 ± 14%, and 28.0 ± 11%, respectively; p = NS), registration of IPA injuries with 3moPA scarring demonstrated that 59.0 ± 19% of scar resulted from NE tissue, 30.6 ± 15% from HE tissue, and 10.4 ± 5% from tissue identified as normal. Paired t-test comparisons were all statistically significant among NE, HE, and normal tissue types (p < 0.001). Arrhythmia recurrence at 1-year follow-up correlated with the degree of wall enhancement 3moPA (p = 0.02). Conclusions Radiofrequency ablation results in heterogeneous injury on LGE MRI with both HE and NE wall lesions. The NE lesions demonstrate no-reflow characteristics and reveal a better predictor of final scar at 3 months. Scar correlates with procedure outcomes, further highlighting the importance of early scar prediction.

Expert Takes1 quote

“As advanced techniques for scar imaging become available, MRI will be an indispensable tool within the catheter lab itself.”

Nassir Marrouche, Director of Electrophysiology, University of UtahUniversity of Utahauto_pipelineView source

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