Prognostic value of left ventricular global longitudinal strain in secondary mitral regurgitation: a systematic review

Background/Introduction In mitral regurgitation (MR), optimal timing of intervention depends on early detection of left ventricular (LV) dysfunction. Conventional metrics such as ejection fraction and LV dimensions may remain preserved until advanced myocardial damage has already developed. LV global longitudinal strain (GLS) is a sensitive marker of subclinical myocardial dysfunction and may improve risk stratification beyond standard echocardiographic parameters. Purpose To evaluate the prognostic value of LV GLS in adults with moderate-to-severe secondary MR assessed before any surgical or transcatheter intervention. Methods A systematic review was conducted according to PRISMA 2020. PubMed, Web of Science, Scopus, ScienceDirect, and the Cochrane Library were searched from inception. Cohort studies enrolling adults with moderate-to-severe secondary MR that evaluated LV GLS and reported clinical outcomes were included. Outcomes comprised all-cause mortality, heart failure hospitalisation, major adverse cardiovascular events, and composite cardiovascular endpoints. Two reviewers independently screened studies and extracted data. Effect measures were hazard ratios (HRs) with 95% confidence intervals (CIs). Risk of bias was assessed using the Quality In Prognosis Studies (QUIPS) tool. Results The search identified 1,051 records; after deduplication and screening, 4 cohort studies met inclusion criteria. Two studies reported GLS as a continuous variable, whereas two used categorical thresholds or non-linear approaches. Across all studies, impaired GLS was consistently associated with a higher risk of adverse outcomes despite heterogeneity in outcome definitions and covariate adjustment. In categorical analyses, marked GLS impairment was associated with increased risk (e.g., HR 2.70, 95% CI 1.11–6.57 versus preserved GLS). In continuous analyses, higher absolute GLS values were associated with lower risk (e.g., HR 0.857 per 1% absolute increase, 95% CI 0.798–0.919). Differences in GLS reporting, modelling strategies, and adjustment sets precluded quantitative synthesis and pooled estimates. Overall risk of bias was low-to-moderate, with residual confounding representing the main limitation. Conclusions In adults with moderate-to-severe secondary MR evaluated before intervention, impaired LV GLS is consistently associated with worse clinical outcomes, including mortality and major cardiovascular events, even when conventional measures are preserved. These findings support GLS as a robust prognostic marker for risk stratification. Standardised prospective studies reporting GLS as a continuous variable with harmonised analytical approaches are needed to enable pooled estimates and clinically actionable thresholds.