Ringlike late gadolinium enhancement: prevalence, association with cardiac phenotype, and patient outcome in an unselected cohort referred for cardiovascular magnetic resonance imaging
Authors: Filomena D , Vandenberk B , Dresselaers T , Masci P G , Robyns T , Bogaert J 
Published: October 2024

Abstract

Background
The identification of a non-ischemic ringlike enhancement in the left ventricular (LV) myocardium by cardiac magnetic resonance imaging (CMR) has emerged as a significant biomarker associated with arrhythmogenic cardiomyopathy (CMP) and adverse patient outcomes. Recently, the term "scarring CMP" has been also proposed to encompass various conditions characterized by a high burden of non-ischemic, often ring-like, myocardial scarring, including both genetic and acquired etiologies.

Purpose
To systematically evaluate CMR phenotypic traits and etiologic backgrounds in patients with ringlike enhancement and to assess the burden of adverse outcomes during follow-up (FU).

Methods
This is a single-center, retrospective analysis of prospectively enrolled patients undergoing CMR (from 2002 to 2024). Ringlike late gadolinium enhancement (LGE) was defined as continuous enhancement in three or more adjacent segments based on the AHA 17 segment model. Patients records were reviewed for etiologic classification and FU assessment.

Results
Among 23.472 patients, 19.696 (84%) underwent LGE assessment. In 152 patients (0.77%; 73% male; mean age 48.5 ± 17 years) a ringlike LGE was identified. The mean number of LV segments with LGE was 10 ± 3. Right ventricular (RV) LGE was present in 23% of subjects. LV fatty metaplasia was detected in 22%. Infero-lateral segments were most frequently affected.
CMR showed the following morpho-functional features: LV dilatation (53%), LV hypokinesia (69%), LV hypertrophy (10.5%), LV non-compaction (11%), RV dilation (26%), and RV ejection fraction &lt; 40% (21%). Phenotypic classification according to 2023 ESC guidelines identified dilated CMP phenotype (43%), non-dilated LV CMP phenotype (39%), predominant arrhythmogenic right ventricular phenotype (6%), hypertrophic phenotype (7%). 5% of cases remained unclassified, all of them showing LV dilated non-hypokinetic phenotype.
Genetic analysis was performed in 101 patients (66%).
Etiologic classification revealed non-desmosomal gene related CMP (24%), desmosomal gene related CMP (8%), inflammatory CMP (16%), genetic neuromuscular diseases (5%), congenital metabolic errors (3%), familiar gene elusive CMP (2%) and unknown etiology (45%). Notably, only 17% of patients classified as having inflammatory CMP and 66% of those with unknown etiology underwent genetic testing, with negative results.
The median follow-up duration was 3 (IQR: 1-7) years. All-cause mortality occurred in 10.5% of patients, while 17% experienced sustained ventricular tachycardia, appropriate implantable cardioverter-defibrillator therapies, or sudden cardiac death. Heart transplantation or left ventricular assist device implantation was required in 8% of cases.

Conclusion
Ringlike LGE is a rare, non-disease-specific feature that can be found in different morpho-functional CMP phenotypes. It is associated with frequent genetic-determined etiology and high burden of arrhythmic and non-arrhythmic outcomes.