ABC | Volume 112, Nº4, April 2019

Short Editorial Quantification of Left Atrial Tissue Remodeling Using Intra-Atrial Dyssynchrony by Cardiac Magnetic Resonance Imaging Patrick T. Bering 1 e João L. Cavalcante 2,3 Medstar Washington Hospital Center, 1 Washington – District of Columbia Minneapolis Heart Institute - Abbott Northwestern Hospital, 2 Minneapolis – Minnesota Valve Science Center - Minneapolis Heart Institute Foundation, 3 Minneapolis – Minnesota Short Editorial related to the article: Intra-Atrial Dyssynchrony Using Cardiac Magnetic Resonance to Quantify Tissue Remodeling in Patients with Atrial Fibrillation Mailing Address: João L. Cavalcante • Director, Cardiac MRI, Structural Cardiovascular Imaging and Core Labs - Minneapolis Heart Institute - 800 East 28 th Street, Minneapolis, MN, 55407 Email: joao.cavalcante@allina.com Keywords Atrial Fibrillation; Remodeling Atrial; Atrial Dyssynchrony Diagnostic Imaging; Magnetic Resonance Imaging. DOI: 10.5935/abc.20190073 Morphological and functional characteristics of the left atrium (LA) play a key role in the pathogenesis of atrial fibrillation (AF), which represents a global health burden as the most common cardiac arrhythmia encountered in clinical practice. 1 For patients with drug-refractory AF, catheter-ablation may aid in a) prolonged restoration of sinus rhythm, b) decreased in total arrhythmic burden, symptomatic improvement, and c) better quality of life. However, catheter‑ablation may not have a durable effect for a significant number of patients despite repeated procedures. 2 A variety of innovative procedural technologies aim to improve patient freedom from AF. Scientific progress in the identification of patient characteristics that suggest a favorable or poor likelihood of procedural success may enhance patient selection for catheter-ablation and optimize time utilization for the cardiac electrophysiologist. Cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE) has been shown to be a promising, non-invasive tool for the measurement of LA fibrosis, which predicts the recurrence of AF after catheter‑ablation. 3,4 While this tissue characterization of the LA represents a promising technology for patients with AF in whom catheter-ablation is being considered, it remains mostly these days at expert centers, has labor-intensive post-processing and necessitates the use of gadolinium contrast, which may exclude patients who have advanced kidney disease or allergic reactions to gadolinium. Functional assessment with intra-atrial dyssynchrony utilizing tissue‑tracking represents an elegant technique to characterize LA mechanics that does not require gadolinium contrast or significant post-processing and was recently shown to correlate with the recurrence of AF after catheter-ablation. 4 In this issue, Ciuffo et al. 5 advance the understanding of adverse LA remodeling and dysfunction in patients with AF. Using CMR to measure intra-atrial dyssynchrony in sinus rhythm, defined as the standard deviation of the time to the peak longitudinal strain [SD-TPS (%)] and pre-atrial contraction strain [SD-TPS preA (%)] corrected by the cycle length. LA fibrosis was quantified using LGE images, which, interestingly, did not differ significantly between paroxysmal and persistent AF types. Notably, SD-TPS was significantly higher in patients with persistent AF than those with paroxysmal AF, although this association did not hold true for SD-TPS preA between the AF types. On multivariable adjustment for age, sex, BMI, AF type, history of heart failure, OSA, hypertension, minimal LA volume and maximum LA longitudinal strain, both SD-TPS and SD-TPS preA remained significantly associated with LA LGE, although the signal was much stronger for SD-TPS. Inter- and intra-reader reproducibility was excellent for both indices, and the data were post-processed in a short amount of time. These findings highlight the potential for intra-atrial dyssynchrony by CMR to represent a fast and accurate surrogate of LA fibrosis, especially in the prediction of AF recurrence after catheter-ablation. 3,4 The authors have appropriately acknowledged the potential for selection bias in their non-randomized, retrospective cohort, and this technique requires patients to be in sinus rhythm at the time of CMR imaging. Still, Ciuffo et al. 5 have added valuable insights into the understanding of LA remodeling in AF and must be praised for their work, which studied a real-world population and considered the important concern of work-flow for CMR post-processing. Their findings should stimulate more research into the use of intra-atrial dyssynchrony as non-invasive risk stratification for patients with AF, which does not require gadolinium contrast to enhance patient selection for invasive therapies such as catheter-ablation. 451