BMJ Open. 2026 Sep 22;16(9):e121972. doi: 10.1136/bmjopen-2026-121972.
ABSTRACT
OBJECTIVES: Mitral regurgitation (MR) induces progressive atrial remodelling and dysfunction, yet conventional metrics may underestimate early mechanical impairment. This systematic review synthesised evidence on left atrial strain (LAS) across MR phenotypes, its prognostic utility and its response to intervention.
DESIGN: Systematic review conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
DATA SOURCES: MEDLINE, PubMed, Embase, CENTRAL and Web of Science were searched from 1 January 2010 to 10 July 2026.
ELIGIBILITY CRITERIA: Studies of adult patients with MR of any aetiology or severity using speckle-tracking echocardiography to report quantitative LAS. Case reports, reviews, conference abstracts without full text and non-English publications were excluded.
DATA EXTRACTION AND SYNTHESIS: Two reviewers independently extracted data and assessed the risk of bias using the Risk of Bias in Non-Randomised Studies of Exposures tool, with a third reviewer resolving disagreements. Substantial heterogeneity precluded quantitative meta-analysis.
RESULTS: Left atrial reservoir strain (LASr) was universally reduced in patients with MR compared with controls across all aetiologies. Secondary MR demonstrated more severe impairment than primary MR, reflecting combined volume and pressure overload. Progressive LAS deterioration accompanied increasing MR severity, with LASr independently predicting surgical necessity and outperforming left ventricular global longitudinal strain as a severity marker. Multiple prognostic thresholds demonstrated independent predictive value for adverse outcomes: LASr <35% predicted cardiovascular events, while LASr ≤15% in secondary MR independently predicted mortality. Postintervention LAS responses demonstrated substantial heterogeneity; patients achieving ≥15% LASr improvement experienced significantly lower all-cause mortality and heart failure hospitalisation, establishing LAS recovery as a surrogate marker of successful reverse remodelling.
CONCLUSIONS: LASr is a sensitive, consistent marker of atrial dysfunction in MR, identifying mechanical impairment prior to irreversible remodelling. As most supporting evidence is retrospective and single-centre, further prospective validation will help establish standardised thresholds for clinical use.
PROSPERO REGISTRATION NUMBER: CRD420251126721.
PMID:42772885 | DOI:10.1136/bmjopen-2026-121972