Relation of Right Atrial Mechanics to Functional Capacity in Patients With Systemic Sclerosis

Cardiac involvement in systemic sclerosis (SSc) implies a worse prognosis. Little is known about the right atrial (RA) mechanics in this disease, but recent data suggest that it correlates well with the functional capacity of the patients in conditions with known right heart involvement. Thus we aimed to investigate the abnormalities of the RA function as compared with healthy subjects and to assess the potential correlations between RA mechanics and the functional capacity in SSc patients using 2D speckle tracking technique. A total of 70 SSc patients (age: 57 ± 12 years) were investigated. Functional capacity was measured with 6-minute walk test (6MWT). Echocardiographic parameters of the right ventricular (RV) systolic function (TAPSE, RVFAC), parameters of the tricuspid inflow (E, A), and tricuspid annular systolic (S), early- (e') and late- (a') diastolic myocardial velocities were measured. RV wall thickness was obtained. RA reservoir (ε_R), conduit (ε_CD), and contractile (ε_CT) strain were measured. RA stiffness was calculated as ratio of E/e' to ε_R. Echocardiographic data were compared with an age- and gender-matched group of 25 healthy volunteers. RA ε_R (49.3 ± 10.7 vs 59.6 ± 9.9%, p = 0.000) and ε_CD (26.8 ± 8.1 vs 34.3 ± 7.3%, p = 0.000) were significantly lower in SSc patients. No significant difference was found in ε_CT (22.9 ± 5.8 vs 25.3 ± 5.7%, p = 0.082). RA stiffness was significantly increased in SSc patients (0.11 ± 0.04 vs 0.08 ± 0.02, p = 0.001). 6MWT distance was 391 ± 95m. In stepwise multiple linear regression analysis RV wall thickness (r = -0.289, p = 0.030) and RA stiffness (r = -0.418, p = 0.002) became independent predictors of 6MWT distance. In conclusion, RA ε_R and ε_CD are impaired, while RA stiffness is increased in SSc compared with healthy subjects. Speckle tracking-derived RA stiffness is turned out to be one of the main determinants of the functional capacity in SSc patients.