In 46 patients with moderate-to-severe degenerative mitral regurgitation (DMR), integrating left atrial reservoir strain (LASr) with late gadolinium enhancement (LGE-CMR) fibrosis percentage achieved an AUC of 0.91 for identifying concurrent atrial fibrillation (AF) — outperforming any single imaging parameter. AF patients showed lower LASr, higher left atrioventricular coupling index (LACI; best single predictor, AUC 0.85 at cutoff 58.59%), larger LA fibrosis area (>13.73 cm²), and elevated collagen turnover biomarker CITP, collectively pointing to advanced structural remodeling as the mechanistic bridge between DMR and AF.
This preprint, posted on medRxiv and not yet peer-reviewed, fills a meaningful gap: most DMR imaging studies rely on volumetric or functional echo alone, ignoring myocardial fibrosis quantification. The LACI finding is particularly notable — this relatively novel coupling index captures both atrial dilation and ventricular-atrial mechanical mismatch, and its strong discriminative performance here adds to a small but growing literature supporting its clinical utility. However, the 46-patient retrospective cohort is too small to support generalized cutoff adoption, and the nine-month follow-up limits conclusions about AF incidence or arrhythmic progression. LGE-CMR also carries practical barriers — cost, gadolinium exposure, and scan time — that constrain routine use. The CITP biomarker correlation hints at a systemic fibrotic phenotype worth investigating prospectively. Pending peer review and replication in larger cohorts, this work is best viewed as hypothesis-generating but methodologically interesting for refining pre-operative AF risk stratification in DMR.