Correlation of echocardiographic findings of pulmonary hypertension with six-minute walk test and plasma pro b-type natriuretic peptide level in systemic lupus erythematous

INTRODUCTION Pulmonary arterial hypertension (PAH) is an increasingly recognized complication of systemic lupus erythematous (SLE), which may remain undiagnosed if asymptomatic. OBJECTIVE This study aimed to determine the correlation between echocardiographic findings of PAH and six-minute walk test (6WMT) and serum pro b-type natriuretic peptide (proBNP) level in patients with SLE. METHODS This cross-sectional study was performed on 50 SLE patients selected from patients referring to the outpatient's department of the Rheumatology Clinic at Imam Reza Hospital in Mashhad, Iran, from July 2013 through September 2014, using resting transthoracic echocardiography to estimate systolic pulmonary artery pressure (sPAP). Variables were summarized as counts and/or percentages or as mean±SD. Inter-group comparisons were made performing two-tailed Fisher's exact test or Mann-Whitney U test, using SPSS 22. RESULTS In general, five out of fifty patients were diagnosed to have PAH with sPAP>30 mmHg (range: 31-40 mmHg) based on echocardiographic findings. Spirometric parameters did not show any differences between the two groups (p>0.05), while the difference in total distance walked during six minutes and serum proBNP level between SLE patients with and without PAH was significant (P<0.05). A high correlation was found between PAP and serum proBNP level, but not between PAP and the distance walked during six-minutes in SLE patients. CONCLUSION The point prevalence of PAH in SLE patients was 10%; the significant correlation between PAP and serum proBNP level suggests that it can be used as a valuable marker for early diagnosis of asymptomatic pulmonary hypertension in patients with SLE.