High levels of serum lactate dehydrogenase correlate with the severity and mortality of idiopathic pulmonary arterial hypertension.

Liver dysfunction reflects the status of heart failure, and previous studies have demonstrated that serum lactate dehydrogenase (S-LDH) levels are increased in patients exhibiting heart failure and liver dysfunction. Right heart failure is a main characteristic of idiopathic pulmonary arterial hypertension (IPAH). The aim of the present study was to assess the prognostic significance of S-LDH levels in patients with IPAH. S-LDH levels were determined in 173 patients with IPAH, and these patients were subclassified into two groups according to a defined upper reference limit of S-LDH (250 IU/l). Right heart catheterization was performed in all patients. A total of 53 patients were found to have elevated S-LDH to ≥250 IU/l. In a mean follow-up period of 31.2±17.9 months, 57 patients succumbed. In the group with lower S-LDH levels (S-LDH <250 IU/l), 16.7% of the patients succumbed, compared with 69.8% of patients in the group with higher S-LDH levels (S-LDH ≥250 IU/l). The Kaplan-Meier survival curves demonstrated that patients with higher S-LDH levels had a significantly lower survival rate than did those with lower S-LDH levels (log-rank test, P<0.001). Cox proportional hazard analyses identified reduced body mass index, reduced cardiac index, elevated World Health Organization functional class, higher S-LDH and an absence of PAH-targeted therapy as significant predictors of adverse outcomes. In conclusion, elevated S-LDH is a risk factor for mortality in patients with IPAH.