As PTT and PBVi appear to serve as surrogate biomarkers of cardiopulmonary disease and are known to correlate with biochemical (brain natriuretic peptide), clinical (6-min walk test, New York Heart Association functional classification) and structural and hemodynamic parameters (cardiac output, pulmonary artery wedge pressure, valve disease severity), it is not surprising that these indexes are associated with conventional clinical endpoints. The gene discussed is NPPB; the disease is cor pulmonale.