Correlation between serum sodium level and prognosis of pulmonary arterial hypertension

Objective To investigate the relationship between serum sodium level and prognosis in patients with pulmonary arterial hypertension (PAH). Methods 100 patients with PAH were enrolled from January 2014 to December 2016 at Wuhan Asia Heart Hospital retrospectively, including 57 patients with PAH associated with congenital heart disease (CHD), 29 patients with idiopathic pulmonary arterial hypertension (IPAH) and 14 patients with PAH associated with connective tissue disease (CTD). According to the patient's blood sodium level, the patients were divided into hyponatremia group (blood sodium <135 mmol/L, 40 cases) and normal blood sodium group (60 cases). The correlation between serum sodium level and prognosis of PAH was analyzed. Results Compared with the normal blood sodium group, the patients with hyponatremia had more clinical symptoms (82.5% vs. 45.0%, P<0.001), higher incidence of edema (75.0% vs. 27.8%, P<0.001), higher hospitalization rate (72.5% vs. 38.3%, P<0.001), higher right atrial pressure [(13.4±5.1) mmHg vs. (8.2±3.6) mmHg, P<0.001], lower cardiac output index [(21.2±8.5) ml/m2vs. (34.7±8.9) ml/m2,P<0.01], ratio of right ventricular diameter to the left ventricular diameter (1.93±0.45 vs. 1.31±0.52, P<0.001) was higher in hyponatremia group while, and tricuspid annular plane systolic excursion [(1.52±0.5) cm vs. (1.93±0.40) cm, P=0.001] was lower. But the mean pulmonary artery systolic pressure was similar between two groups [(48.9±8.3) mmHg vs. (48.5±10.7) mmHg, P=0.542]. Conclusion The level of blood sodium is significantly correlated with the severity and prognosis of patients with PAH. Hyponatremia may be an important indicator for poor prognosis in PAH patients, but more research is needed.