Analysis of small subgroup of PAH patients who died revealed that they had significantly higher WHO class at baseline visit (2.75 ± 0.46 vs 2.0 ± 0.50, p = 0.01), BNP concentrations (456 ± 280 vs 164 ± 47 pg/ml, p = 0.006) and lower 6MWT distances (312 ± 90 vs 425 ± 83 m, p = 0.01). This evidence concerns the gene NPPB and pulmonary arterial hypertension.