Severe Rheumatic Mitral Stenosis, Worse Left Atrial Mechanics is Closely Associated with Echo Criteria for Intervention

Abstract

Background: Rheumatic mitral valve (MV) stenosis is associated with progressive left atrial (LA) fibrosis and functional impairment, Pulmonary artery systolic pressure (PASP) and right ventricular (RV) dysfunction. The aims of the study were to determine in those patients with severe MV stenosis if LA mechanical function as assessed by speckle tracking echocardiography could identify those with increased PASP, atrial fibrillation (AFib), and RV dysfunction.

Subjects and methods: Patients with severe MV stenosis were identified from the institutional echo database. Echocardiograms were read off line and measurements included atrial and ventricular strain. Patients were divided into tertiles of LA reservoir strain (LASr) values and data compared between the groups.

Results: Ninety-seven patients, 67 females, mean age 47.4 ± 11.9 years, had MV mean gradient of 8.3 ± 5.1 mmHg, MV area by pressure half time of 1.3 ± 0.3 cm² and LASr of 11.18% ± 6.4%. Those patients in the lowest LASr tertile had more AFib (72%, P = 0.0001), PASP >50 mm Hg (39%, P = 0.005), and worst RV impairment. In multivariable logistic regression analysis, LASr, age, and mean MV gradient were the independent predictors of AFib and PASP >50 mm Hg. Cutoffs, determined by receiver operating characteristic curve analysis had high specificity for the composite outcome of Afib and PASP >50 mmHg (85% for LASr <7.7%).

Conclusion: In severe MV stenosis LASr, age and mean MV gradient, are independent predictors of Afib and PASP >50 mmHg. LASr <7.7% has high sensitivity and specificity in identifying those who meet ESC guideline 2017 criteria for valve intervention, suggesting its potentially helpful addendum to the surveillance of patients with MV stenosis.

Keywords: Atrial fibrillation; atrial strain; mitral stenosis; pulmonary hypertension; rheumatic heart disease; valvular heart disease.

Figure 1

Flowchart describes the derivation of the study population

Figure 2

Box-plot of hemodynamic parameter according to LA reservoir strain tertiles. Box-plot for stroke volume index. EF: Ejection fraction, LVGLS: Global longitudinal strain of the left ventricle, PASP: Pulmonary artery systolic pressure, TAPSE: Tricuspid annular plain systolic excursion, (right ventricular free wall longitudinal strain) are represented according to tertiles of left atrial reservoir strain (Group 1:33 subjects, left atrial reservoir strain ≤7%; Group 2: 32 subjects, left atrial reservoir strain 8-13%, Group 3: 32 subjects left atrial reservoir strain ≥14%)

Figure 3

Strain of the left atrium and right ventricle. Tracing and strain of the left atrium, (a) and right ventricle (b) by Arena version 4.6 software

Figure 4

Receiver operating characteristic for atrial fibrillation and PASP. Left atrial reservoir strain was the parameter with higher under the curve either for atrial fibrillation or PASP ≥50 mmHg (0.8 and 0.726 respectively) among the parameters tested (left atrial volume, mitral valve mean gradient, mitral valve area by pressure half time)

Figure 5

Receiver operating characteristic for the patients the meet the ESC 2017 criteria for mitral valve stenosis intervention left atrial reservoir strain had the higher area under the curve

Figure 6

(a) 4 chamber view: severely dilated atria. (b) MV area was evaluated using PHT method (220/PHT) or by 2D planimetry (e) and 3D planimetry (f). (c), (d) Peak and mean mitral gradients were obtained from the apical position using CW Doppler recordings for the estimation of MV stenosis severity (peak and mean gradients)