The current guidelines associate indications for surgery in mitral regurgitation (MR) with left ventricle size and function. However, there is not enough emphasis in current guidelines on left atrial function, which is thought to be an important factor predicting adverse outcomes in MR. The aim of this study was to investigate the left atrial function at different stages of mitral regurgitation and its value in predicting the indications of mitral valve surgery.
This was a retrospective study with 163 consecutive chronic primary MR patients who underwent color doppler echocardiography at the Guangxi Zhuang Autonomous Region Second People\'s Hospital between January 2016 and June 2018. All patients were in sinus rhythm, classified into three groups, according the degree of mitral regurgitation. Comparison was made with 30 control patients. Using Simpson\'s methods, we recorded maximal left atrial volume, left atrial volume before active contraction and minimal left atrial volume, from which left atrial expansion index, left atrial passive emptying fraction, left atrial active emptying fraction, and the total left atrial emptying fraction were derived.
Left atrial volume was expanded and left atrial emptying fraction was reduced in the mitral regurgitation group. By multivariate analysis, left atrial passive emptying fraction and left atrial active emptying fraction were independent predictors of mitral regurgitation requiring surgery. Using receiver-operating characteristic analysis, left atrial passive emptying fraction <97.4% demonstrated 98% sensitivity and 67% specificity for predicting the presence of surgical indication (area under the curve: 0.91; P < .001).
During mitral regurgitation, left atrial volume increases and functions decrease. The left atrial passive emptying fraction can be used as an additional tool to predict the indications of mitral valve surgery.

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Current guidelines recommend that the atria be measured in 2D echocardiographic (2DE) apical views using the method-of-disks (MOD) or area-length (AL) technique as an alternative, although no definitive data exists that these are interchangeable. However, standard apical views maximize the long-axis of the left ventricle, rather than the dimensions of the atria, resulting in atrial foreshortening. We hypothesized that the increase in normal values of atrial volumes in the recent guidelines update was driven by data obtained using either the AL technique or dedicated atrial-focused views, which maximize the longitudinal dimension of the atria and thus provide larger volumes than the MOD measurements in standard apical views. We prospectively studied 30 patients (Philips iE33) to compare 2DE measurements of left and right atrial volumes (LAV, RAV) using the MOD and AL techniques in standard and atrial-focused views, against 3D echocardiography (3DE) derived volumes (QLab) as a reference. Compared to standard views, atrial-focused views provided significantly larger MOD volumes for both atria, which were in better agreement with 3DE, as reflected by higher correlation coefficients (LAV: r = 0.95 vs. 0.89; RAV: r = 0.89 vs. 0.84), smaller biases (LAV: -1 ml vs. 7 ml; RAV: 3 ml vs. 7 ml) and tighter limits of agreement. This was also the case for the AL measurements, which were minimally larger than the MOD values (NS) for both atria. In conclusion, atrial-focused views are a more accurate alternative to standard apical views, which provides larger volumes. This finding can explain the increase in the normal values in the recent guidelines update, which was mostly driven by the use of atrial-focused views, rather than by the differences between MOD and AL techniques. This understanding is essential in order to correctly integrate the revised normal values into clinical practice.

BACKGROUND: Left atrial (LA) mechanics in patients with severe mitral regurgitation (MR) remain largely unexplored. The aim of the present evaluation was to assess the effect of severe MR on LA function, its potential relation with conventional surgical indications, and long-term postoperative survival.
METHODS: Two-dimensional speckle-tracking strain and volumetric indices of LA reservoir, conduit, and contractile function were assessed in 121 patients with severe MR and 70 controls. Patients were divided according to the presence (n = 46) or absence (n = 75) of one or more guidelines-based criteria for mitral surgery (symptoms, left ventricular ejection fraction ≤ 60%, left ventricular end-systolic diameter ≥ 40 mm, atrial fibrillation, or systolic pulmonary arterial pressure >50 mm Hg).
RESULTS: In patients with severe MR compared with controls, significant LA reservoir and contractile dysfunction was observed, which was more pronounced in patients with mitral surgery indication (P < .05 for all strain and volumetric indices). Of all indices of LA function, LA reservoir strain was an independent predictor (odds ratio, 0.88; 95% confidence interval, 0.82-0.94; P < .001) and had the highest accuracy to identify patients with indications for mitral surgery (area under the receiver operating characteristic curve, 0.8; 95% confidence interval, 0.72-0.87). A total of 117 patients underwent mitral valve surgery. Patients with LA reservoir strain ≤24% showed worse survival at a median of 6.4 years (interquartile range, 4.7-8.7 years) after mitral surgery (P = .02), regardless the symptomatic status before surgery. LA reservoir strain, on top of mitral surgery indications, provided incremental predictive value for postoperative survival.
CONCLUSIONS: Impaired LA reservoir strain in patients with severe organic MR relates to long-term survival after mitral valve surgery, independently of and incremental to current guidelines-based indications for mitral surgery.