Left atrial strain in heart failure with reduced ejection fraction: from emerging evidence to clinical integration

This editorial refers to ‘Measures of left atrial function and risk of incident atrial fibrillation in patients with heart failure with reduced ejection fraction’, by A. Stanchev et al., https://doi.org/10.1093/ehjci/jeaf205. In recent years, the left atrium (LA) has transformed from a passive bystander to a central player in cardiovascular imaging. Among the most compelling advances is the quantification of LA strain—particularly peak atrial longitudinal strain (PALS) and peak atrial contractile strain (PACS)—which has emerged as a robust and reproducible biomarker of LA function.1–3 The manuscript by Stanchev et al.4 adds significant momentum to this growing body of evidence by demonstrating the predictive value of LA functional indices—left atrial ejection fraction (LAEF), PALS, and PACS—for incident atrial fibrillation (AF) in a large, well-characterized cohort of outpatients with heart failure with reduced ejection fraction (HFrEF). Their results are not only clinically meaningful but also methodologically sound, providing further impetus to consider LA strain as part of routine echocardiographic assessment.5 Historically, echocardiographic assessment of the left atrium has relied heavily on volumetric measurements—most commonly the left atrial volume index (LAVi).2,3 While valuable, LA volume reflects cumulative structural remodelling and lags dynamic physiological alterations. Conversely, LA strain offers a more immediate and sensitive marker of myocardial dysfunction, capturing subclinical abnormalities in reservoir, conduit, and contractile function long before volumetric thresholds are breached.6,7 The work of Stanchev et al.4 leverages this strength by showing that reduced PALS and PACS, as well as decreased LAEF, independently predict the development of AF in patients with HFrEF. Importantly, the study population was free from AF at baseline, and the findings persisted after comprehensive multivariable adjustment. While left atrial enlargement remains a well-established marker of atrial remodelling, it often reflects a relatively late stage of pathophysiological change. In contrast, LA strain—particularly PALS and PACS—can detect functional impairment that precedes volumetric dilation. In the present study, the median LA volume index remained within normal or borderline ranges in both groups (30.0 mL/m² vs. 25.7 mL/m²), yet strain parameters such as PALS and PACS demonstrated independent prognostic value. These findings emphasize the incremental value of LA strain over size-based metrics and underscore its potential to detect subclinical atrial dysfunction earlier in the disease course (Figure 1). Summary of the findings and justification for a larger use of left atrial strain in heart failure. The incremental value of LA strain metrics over established echocardiographic risk markers, including LAVi and LVEF, was demonstrated through improvement in C-indices, with PALS yielding the most pronounced gain. While left atrial enlargement remains a well-established marker of atrial remodelling, it often reflects a relatively late stage of pathophysiological change. In contrast, LA strain, particularly PALS, can identify functional impairment that precedes volumetric dilation. In the present study, the median LA volume index remained within normal or borderline ranges in both groups (30.0 mL/m² vs. 25.7 mL/m²), yet strain parameters such as PALS and PACS demonstrated independent prognostic value. These findings underscore the potential of LA strain to provide earlier insight into atrial dysfunction, even in the absence of overt atrial enlargement.4 In contrast, LAEF and PACS showed attenuation in certain subgroups, particularly in women and in the presence of moderate-to-severe valvular disease, a finding that highlights the complexity of interpreting atrial mechanics when volume overload or sex-specific physiology comes into play. Several aspects of this study warrant emphasis: Cohort strength and follow-up: With a sample size of 452 and a median follow-up of nearly a decade, this retrospective Danish registry study provides robust event rates (26.1% incident AF) and long-term insight into LA remodelling and arrhythmogenic potential.4 Comparative analysis of LA functional measures: The authors not only evaluated LAEF, PALS, and PACS but also analysed their intercorrelations and incremental prognostic value. While PALS and PACS were highly correlated (R² = 0.70), LAEF showed only modest correlation with either strain parameter. This divergence supports the complementary—and not redundant—value of these indices. Subgroup analyses: Intriguingly, the prognostic role of LAEF and PACS was attenuated in women and patients with valvular heart disease. In contrast, PALS remained predictive regardless of sex or valvular pathology, highlighting its potential universality and resilience across subgroups. Real-world implications for HFrEF management: Given that AF is a known driver of morbidity in HFrEF, the ability to anticipate its development using a widely accessible, non-invasive tool like echocardiography is a notable clinical advance. Despite the convincing evidence presented by Stanchev et al. and others, LA strain has not yet achieved the same clinical penetration as left ventricular strain or volumetric assessment.4 Several barriers must be acknowledged: Standardization across vendors and platforms: Although inter- and intraobserver reproducibility of LA strain has been reported as high, variability across vendors, software packages, and acquisition protocols continues to limit broader adoption. While the study used EchoPAC, the interoperability and consistency of measurements across imaging platforms require further validation.5,8 Clinical reference values and cut-offs: The field lacks universally accepted reference ranges and prognostic cut-offs for PALS and PACS. In the absence of guideline-endorsed thresholds, interpreting LA strain results remains context-dependent and operator-reliant. The authors wisely modelled hazard ratios per 1% decrease, but further work is needed to define ‘at-risk’ values for clinical use. Integration into risk stratification algorithms: Though this study demonstrates incremental value over conventional parameters, how best to incorporate LA strain into AF risk scores (CHA₂DS₂-VASc, ARIC, or the Framingham AF risk score) remains undefined. Composite imaging-clinical scores may provide better discrimination and should be the focus of future investigations.9 Workflow and training considerations: Routine implementation of LA strain in busy echocardiography labs requires additional time, software licensing, and trained personnel. This creates logistical and financial hurdles that should not be underestimated. Automation and AI-assisted platforms may offer solutions, but require validation in high-throughput clinical settings.3,10 The authors rightly emphasize the pathophysiological underpinnings linking LA dysfunction to AF, especially in HFrEF.11 Elevated LA pressure, atrial fibrosis, calcium overload, and autonomic dysregulation contribute to a pro-arrhythmic substrate long before AF manifests clinically.6 LA strain thus functions not only as a risk marker but as a window into atrial remodelling and myocardial health. Moreover, LA dysfunction is not an isolated phenomenon.2 It interacts dynamically with left ventricular diastolic function, pulmonary hypertension, and right heart failure. Integrating LA strain with complementary parameters—such as LA stiffness index, LA conduit function, and atrial sphericity—may yield a more nuanced risk profile, particularly in heart failure phenotypes like HFpEF and cardiac amyloidosis, where LA involvement is profound. Left atrio-ventricular coupling index is another valuable approach reported.12 To facilitate the widespread adoption of LA strain, a few essential steps must be prioritized: Prospective trials: Ongoing and future prospective studies should evaluate how incorporating LA strain into management strategies alters outcomes in HFrEF and beyond (LA-HCM trial is one that we are starting in France very soon). Sex-specific and valvular insights: The sex-based heterogeneity and impact of valve disease observed in this study deserve deeper exploration. Dedicated trials should assess whether PALS-based risk models perform differently especially by sex. Technological convergence: Inter-vendor reproducibility studies must continue, ideally supported by consensus initiatives like EACVI/ASE task forces.5,10 Development of vendor-neutral strain platforms with cloud-based analysis tools may enhance scalability. Guideline inclusion: The accumulation of robust data, including the present study, calls for consideration of LA strain in future ESC and ASE guidelines for AF risk stratification but also heart failure assessment.13 The study by Stanchev et al.4 is a valuable contribution to a rapidly evolving field. It strengthens the case for LA strain—especially PALS—as a sensitive and clinically relevant marker of AF risk in patients with HFrEF. Their findings move us one step closer to transitioning from validation to clinical implementation. Yet, for LA strain to become a true routine measure, a concerted effort from imaging societies, industry, and clinical stakeholders is required. Bridging this final translational gap is both a challenge and an opportunity we can no longer afford to defer. The data underlying this article will be shared on reasonable request to the corresponding author.