Left atrial dynamics and the pulmonary circulatory-right ventricular uncoupling in patients with severe degenerative mitral regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Background The uncoupling of right ventricular (RV) function to pulmonary circulation (Pc) represents a prognostic index in patients affected by degenerative mitral regurgitation (DMR) undergoing surgical or percutaneous repair. In this context, the deterioration of Left Atrial (LA) dynamics favors the development of pulmonary venous congestion and vascular remodeling, triggering pulmonary hypertension (PH) and right ventricular (RV) dysfunction. However, the relationship between LA function and RV-to-Pc coupling is not well defined in this population. Purpose The aim of the study was to investigate the association between RV-to-Pc uncoupling, assessed by the ratio between tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PAPS), and LA dynamics, evaluated with Speckle Tracking Echocardiography (STE), in patients with DMR. Methods 351 consecutive patients with hemodynamically-significant DMR who were evaluated for cardiac surgery at San Raffaele Hospital and underwent a complete transthoracic and transesophageal echocardiography were retrospectively enrolled (mean age 59±14 years, 65% males). Patients were then stratified in two groups according to TAPSE/PAPS ratio (group I: TAPSE/PAPS >0.4 mm/mmHg; group II: TAPSE/PAPS ≤0.4 mm/mmHg). LA function was evaluated analyzing LA strain at peak relaxation (Global peak atrial longitudinal strain) and STE analysis was performed offline. All the patients enrolled were in sinus rhythm. Results At baseline, patients exhibited normal LV dimensions and function (EDVi 70±20 ml/m2, LVEF 63±6%), increased LA size (48±20 ml/m2) and a mean GPALS of 26±13%. Additionally, a preserved RV function and coupling with PC was found in the population in study (average TAPSE/PASP at admission: 0.84±0.2 mm/mmHg), with only 10% of the cohort exhibiting a reduced TAPSE/PAPS ratio. When stratified according to RV-to-PC coupling, patients with higher TAPSE/PAPS (>0.4 mm/mmHg) exhibited significantly higher values of LA reservoir strain (group I: GPALS 27.8±12.7% vs group II GPALS 22.7±11.3%; p = 0.04) (Figure 1, 2). Additionally, a direct correlation between LA-Strain values and TAPSE/PAPS ratio was noticed (r=0.3, CI 95% 0.21–0.5; p<0.001). Conclusions In DMR, there is a strong association between echo-derived measures of LA mechanics and RV to Pc uncoupling, with higher values of LA strain correlating with a better RV functioning and coupling. These results, although preliminary, suggest the importance of a multiparametric approach in the risk-stratification of these patients, potentially improving the long-term outcome.