Mitral Surgery: Is GLS a Better Predictor of Success Than LVEF?

Mitral regurgitation surgery: beyond the ejection fraction

In the management of severe primary mitral regurgitation (MR), surgery — repair or replacement — remains the gold standard. However, the practitioner faces a hemodynamic paradox: correcting the regurgitation abruptly reduces preload, which often leads to a drop in left ventricular ejection fraction (LVEF) that can persist over the long term, even if preoperative values were normal. This study addresses the limitations of LVEF, a load-dependent parameter, by exploring the utility of Speckle-tracking echocardiography (STE) and Myocardial Work (MW).

The objective of this prospective study was to precisely describe acute and late changes in cardiac function through strain indices (GLS, PALS) and myocardial work (GWI, GWE). Beyond simple hemodynamic observation, the authors sought to identify preoperative echocardiographic predictors capable of anticipating long-term clinical improvement (NYHA class).

The central hypothesis is based on the superior sensitivity of STE and MW indices in detecting subclinical dysfunction and more accurately reflecting actual myocardial performance, regardless of fluctuating loading conditions during the immediate postoperative phase and the 26-month follow-up.

Methodology for the prospective evaluation of myocardial function

This prospective observational study recruited 42 consecutive patients (mean age 65 ± 12 years, 50% male) suffering from severe primary mitral regurgitation (MR) with preserved left ventricular ejection fraction (LVEF) (mean 59 ± 4%). Exclusion criteria included atrial fibrillation, history of cardiac surgery, and concomitant coronary or aortic interventions.

The experimental protocol followed the patients over three distinct periods:

• Baseline: Complete clinical and echocardiographic evaluation before oral surgery.
• Early postoperative period: Evaluation performed within the week following mitral valve repair or replacement, during the hospitalisation phase.
• Long-term follow-up: A subgroup of 32 patients underwent re-evaluation after a mean period of 26 ± 5 months.

Cardiac performance analysis was performed using standard 2D echocardiography and Speckle-Tracking Echocardiography (STE) to measure global longitudinal strain (GLS) and atrial strain (PALS). Myocardial Work (MW) calculation was performed by integrating strain data with peripheral blood pressure (pressure-strain loops) to define the global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Predictors of symptom improvement (NYHA class) were identified by statistical analysis (ROC curves).

Postoperative dynamics: Acute decline and long-term functional recovery

The study included 42 patients (mean age 65 ± 12 years, 50% male) presenting with severe primary mitral regurgitation (MR) with preserved left ventricular ejection fraction (LVEF) (mean 59 ± 4%). The results highlight a dissociation between LVEF and myocardial strain indices (STE) during follow-up.

Acute postoperative phase: a collapse in performance indices

In the week following the procedure (valve repair or replacement), a significant reduction in hemodynamic load was observed, accompanied by a drop in functional parameters:

• LVEF: Reduced in 48% of patients (n = 20).
• Myocardial Work (MW): Global Work Index (GWI) decreased in 79% of patients (n = 33).
• STE: A decrease in Speckle-Tracking parameters was noted in all cardiac cavities, reflecting the immediate impact of surgery on ventricular mechanics.

Long-term follow-up (26 ± 5 months): the Strain rebound

Of the 32 patients evaluated over the long term, a notable functional recovery was documented, although selective:

Predictors of symptom persistence

The analysis identified a key preoperative marker for anticipating clinical recovery. A basal left ventricular GLS > -17.7% (representing a less negative, and therefore impaired, strain) allows for the identification of patients with persistent symptoms at long-term follow-up (AUC 0.68, p = 0.02).

Concretely, if the preoperative GLS is already altered beyond this threshold, the subjective functional benefit after surgery is statistically lower, despite the correction of the valvular leak.

Clinical analysis: the decoupling between LVEF and GLS

The results of this study highlight a postoperative haemodynamic paradox: the immediate drop in left ventricular ejection fraction (LVEF) in 48% of patients and in the Global Work Index (GWI) in 79%. This acute decline, observed as early as the first week, does not reflect intrinsic myocardial impairment, but rather the sudden increase in afterload following the suppression of mitral regurgitation. In the long term (26 ± 5 months), the study reveals a notable decoupling: while LVEF does not return to its baseline values, Global Longitudinal Strain (GLS) and Myocardial Work (MW) parameters significantly improve in more than 70% of subjects. This recovery of GLS is a more faithful reflection of reverse remodelling and the actual clinical improvement of the patients.

Predictive value and limitations of the study

The key point for practice lies in the identification of a prognostic threshold: a preoperative GLS > -17.7% identifies patients at risk of long-term persistence of symptoms (NYHA) (AUC 0.68, p = 0.02). This confirms that Speckle-Tracking Echocardiography (STE) is more sensitive than LVEF for detecting subclinical dysfunction. However, the scope of these results is limited by the modest size of the cohort (n=42 patients recruited, 32 followed long-term) and the strict exclusion of patients with atrial fibrillation or presenting coronary or aortic comorbidities, which restricts generalisation to the global population of primary mitral regurgitation.

Implications for post-surgical follow-up

Unlike LVEF, which remains influenced by loading conditions, myocardial work (MW) indices and GLS offer a more stable view of cardiac performance. The study suggests that assessing myocardial work (GWI, GWE) provides a better understanding of early postoperative LVEF decline as a physiological adaptation. For the clinician, integrating GLS into the preoperative assessment now seems essential to refine surgical timing before the onset of irreversible myocardial dysfunction.

Summary of results

This prospective study of 42 patients demonstrates that after an immediate post-operative drop in LVEF (48% of cases) and Global Work Index (79%), only GLS significantly improves in the long term (26 ± 5 months) in more than 70% of subjects. Impaired preoperative GLS (> -17.7%) was identified as the key predictor of long-term functional symptom persistence (AUC 0.68; p = 0.02), whereas LVEF remains stably decreased.

In concrete terms, for the practitioner:

• Do not be alarmed by a low LVEF postoperatively: LVEF may remain permanently lower than baseline values without reflecting the actual functional status. GLS is a much more reliable indicator of myocardial recovery during follow-up.
• Evaluating functional prognosis via basal GLS: A preoperative GLS threshold higher than -17.7% (indicating impaired strain) should alert you to the risk of persistent symptoms despite technically successful surgery.
• Using myocardial work (MW) in the acute phase: The Global Work Index (GWI) allows for better monitoring of LV performance immediately after the procedure, as it is independent of sudden variations in afterload, unlike conventional strain.

Technical glossary of the study

GLS (Global Longitudinal Strain): A true "early warning system" for myocardial function, GLS measures the longitudinal deformation of the left ventricle via Speckle-Tracking. In this study, it proves to be much more sensitive than the ejection fraction for detecting subclinical dysfunction. Furthermore, a preoperative GLS higher than -17.7% is the gold standard identifying patients at risk of long-term persistent symptoms.

MW (Myocardial Work): This innovative method estimates left ventricular performance by integrating strain data with ventricular pressure (estimated via peripheral blood pressure). It is the missing link for evaluating cardiac function independently of loading conditions (afterload), which is crucial in the changing context of mitral surgery.

GWI (Global Work Index): Represents the total work generated by the ventricle, calculated as the area inside the pressure-strain loop. For the practitioner, it is a global indicator of energy performance. The study shows that it drops in 79% of patients immediately after the procedure before normalising.

PALS (Peak Atrial Longitudinal Strain): An index of left atrial deformation, PALS is used here as a marker of atrial fibrosis and functional status. Its preoperative degradation is correlated with a less favorable prognosis, highlighting the importance of not only looking at the ventricle during MR.

STE (Speckle-Tracking Echocardiography): Imaging technique analysing the displacement of acoustic "speckles" within the myocardium. It is an automated kinetic dissection that provides finer performance indices than simple visual inspection, particularly for post-surgical follow-up where the human eye reaches its limits.

Pressure-Strain Loop: Visualization tool integrating systolic pressure and strain to quantify myocardial work. It allows for the distinction between constructive work (effective for ejection) and wasted work, offering a comprehensive overview of cardiac efficiency that LVEF alone cannot convey.

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