Introduction: 6-min walking test and NT-proBNP are used for risk stratification in Pulmonary Arterial Hypertension (PAH). Validated risk calculators provide only fixed steps of meters walked (6-MWD) and NT-proBNP cut-off to stratify survival at 1-year.

Aims: we evaluated relationship between survival, 6-MWD and NT-proBNP at time of diagnosis, 6 months (6-m) and 1 year (1-y) follow-up.

Methods: Mann-Whitney U two-sample test was used to assess correlation between 6-MWD, NT-proBNP at baseline, 6-m and at 1-y with survival. Pearson?s correlation coefficient (r) was used to assess the correlation between 6-MWD and NT-proBNP. All tests were 2-tailed and statistical significance level was set at p<0.05.

Results: a monocentric cohort of 60 patients with haemodynamic diagnosis of PAH, WHO I, was studied. At time of analysis, 19 pts died (32%), 13 were lost during follow-up (22%), 2 underwent lung transplant (3%). 16 and 3 pts were respectively on double and triple treatment regimen. A significative correlation between 6-MWD and NT-proBNP was found at baseline and 6-m follow-up (r =-0.343, p=0.018 at baseline; r=-0.349, p=0.016 at 6-month) but not significative anymore at 1-y. NT-proBNP was correlated to survival at any time (baseline p=0.023, 6-m p=0.006, 1-y p=0.001), instead of 6-MWD (baseline p=0.12, 6-m p=0.20, 1-year 0.13).

Conclusion: NT-proBNP showed a significant statistical correlation with survival at any time of clinical evaluation, before and after 1-year treatment period. Despite 6-MWD showed a positive trend for a better survival, it was not statistically relevant. In conclusion, routine NT-proBNP dosage should guide an early aggressive treatment regimen more accurately than 6-MWD.