Integrating LVEF, GLS, and LA strain to define three-category functional LV-LA coupling phenotypes in CABG candidates
S Mohamedhoesein, J Schenk, E Kho, D P Veelo, S M BoekholdtAbstract
Background
LVEF is routinely used to assess LV function in CABG patients but often misses early myocardial dysfunction. GLS and LA reservoir strain (LArs) provide more sensitive measures of ventricular and atrial mechanics, enabling a more precise, chamber specific characterization of preoperative LV-LA coupling. This approach extends beyond existing indices such as the left atrioventricular coupling index (LACI), defined as the ratio of left atrial to left ventricular end diastolic volume and used to quantify atrioventricular coupling.
Purpose
To examine the relationship between LVEF, GLS, and LArs, and to derive a new, functional LV-LA coupling phenotype model in patients scheduled for CABG surgery, that offers a chamber specific preoperative assessment of cardiac vulnerability in CABG candidates than LVEF alone and extends beyond existing indices such as LACI.
Methods
Transthoracic echocardiography was prospectively performed in 37 elective CABG patients (mean age 65 ± 8.1 years; 92% male). Abnormality thresholds were defined as LVEF <50%, GLS >-16%, and LA reservoir strain (LArs) <38%. Prevalence of impaired GLS was compared between reduced and preserved LVEF groups. Mean LArs values were compared between LVEF and GLS groups to assess LV-LA mechanical discordance. Correlations across LVEF, GLS, and LArs were evaluated to characterize atrial-ventricular mechanical relationships. LVEF, GLS, and LArs were then integrated to construct a three-category LV-LA remodeling phenotype model.
Results
Abnormal GLS was significantly more common in patients with reduced versus preserved LVEF (79% vs 26%, p=0.0027). The mean LArs between the LVEF <50% and ≥50% was similar (29.6% ± 13.5 vs 37.2 ± 13.6, p=0.11). Interestingly, the mean LArs was significantly lower in patients with impaired GLS (27.1% ± 10.1 vs 40.5% ± 13.9, p=0.002). Additionally, LVEF showed no meaningful correlation with LArs (r=0.27, p=0.110), whereas GLS demonstrated a significant association (r=-0.49, p=0.002), indicating that atrial mechanical impairment aligns more closely with subclinical LV dysfunction than with LVEF. Integration of LVEF, GLS, and LArs yielded three category remodeling phenotypes (primary remodeling, atypical phenotypes, and normal/healthy remodeling, which captured distinct mechanical patterns and diagnostic discordance, not captured by LVEF only (Figure).
Conclusion
GLS identified myocardial dysfunction in patients with preserved LVEF and showed a strong association with reduced LArs, whereas LVEF did not discriminate LA mechanical impairment. The combination of GLS and LArs may be more representative for assessment of cardiac vulnerability perioperatively. The three category functional LV-LA coupling taxonomy revealed distinct remodeling patterns and diagnostic discordances not captured by LVEF alone or by the existing LACI which is not chamber specific. This integrated framework may enhance preoperative risk characterization in CABG candidates.For image description, please refer to the figure legend and surrounding text.