Left atrial function in patients with rheumatic mitral stenosis: addressing prognostic insights beyond atrial fibrillation prediction

Abstract

Aims: Rheumatic mitral stenosis (MS) frequently leads to impaired left atrial (LA) function because of pressure overload, highlighting the underlying atrial pathology. Two-dimensional speckle tracking echocardiography (2D-STE) offers early detection of LA dysfunction, potentially improving risk assessment in patients with MS. This study aims to evaluate the predictive value of LA function assessed by 2D-STE for clinical outcomes in patients with MS.

Methods and results: Between 2011 and 2021, patients with MS underwent LA function assessment using 2D-STE, with focus on the reservoir phase (LASr). Atrial fibrillation (AF) development constituted the primary outcome, with death or valve replacement as the secondary outcome. Conditional inference trees were employed for analysis, validated through sample splitting. The study included 493 patients with MS (mean valve area 1.1 ± 0.4 cm², 84% female). At baseline, 166 patients (34%) had AF, with 62 patients (19%) developing AF during follow-up. LASr emerged as the primary predictor for new-onset AF, with a threshold of 17.9%. Over a mean 3.8-year follow-up, 125 patients (25%) underwent mitral valve replacement, and 32 patients (6.5%) died. A decision tree analysis identified key predictors such as age, LASr, severity of tricuspid regurgitation (TR), net atrioventricular compliance (C _n), and early percutaneous mitral valvuloplasty, especially in patients aged ≤49 years, where LASr, with a threshold of 12.8%, significantly predicted adverse outcomes.

Conclusion: LASr emerged as a significant predictor of cardiovascular events in this MS cohort, validated through a decision tree analysis. Patients were stratified into low- or high-risk categories for adverse outcomes, taking into account LASr, age, TR severity, and C _n.

Keywords: atrial fibrillation; decision tree analysis; left atrial reservoir strain; rheumatic mitral stenosis; risk prediction.

Graphical Abstract

Left atrial function in patients with rheumatic mitral stenosis. A total of 493 patients with mitral stenosis, age 46.4 ± 12.5 years, were prospectively recruited between 2011 and 2021. Left atrial function was assessed using two-dimensional speckle tracking echocardiography during the reservoir phase (LASr). The primary outcome was the new onset of atrial fibrillation (AF), and the secondary outcome was a composite of death or valve replacement. Based on the decision tree analysis, LASr was the most important predictor of new-onset AF, establishing a cut-off point of 17.9%. Age emerged as the primary predictor for the secondary outcome. However, in patients aged ≤49 years, LASr was the first discriminatory variable with a cut-off point of 12.8% for predicting adverse outcome. 2D-STE, two-dimensional speckle tracking echocardiography; C_n, net atrioventricular compliance; LA, left atrial; LASr, left atrial strain during the reservoir phase; MVR, mitral valve replacement; SR, sinus rhythm; TR, tricuspid regurgitation.

Figure 1

Assessment of LA strain by 2D speckle-tracking echocardiography. (A) An echocardiographic apical four-chamber view with a colour-coded region of interest for LA strain trace. (B) Measurement of LA strain during the reservoir phase (LASr) at end-diastole, as indicated by the arrow.

Figure 2

A flow chart of the study population.

Figure 3

(A) A survival conditional inference tree for new-onset AF. LASr was identified as the most important predictor of new-onset AF. For those with LASr ≤ 17.9%, LA volume was a discriminatory variable. (B) Estimated survival curves for the final nodes provided by the conditional inference tree for new-onset AF. Node 5 is of patients with LASr > 17.9%, Node 3 is of those with LASr ≤ 17.9% and LAVi ≤ 70.6 mL/m², and Node 4 is of those with LASr ≤17.9% and LAVi >70.6 mL/m².

Figure 4

(A) A survival conditional inference tree for event-free survival prediction. The first variable, which best divided the sample, was age with a cut-off point of 49 years. (B) Estimated survival curves for the final nodes provided by the conditional inference tree for cardiovascular events defined as death or the need of mitral valve replacement.

Figure 5

LA strain measurements in two patients with similar LA size and MS severity. (A) LA strain in a patient with MS with favourable outcome overtime, without events. (B) LA strain in another patient who progressed with a worsening of functional class and underwent mitral valve replacement.