Pulmonary hypertension (PH) due to chronic lung disease (WHO Group 3) increases cost and is associated with worse survival when compared to patients with chronic lung disease without PH. However, the clinical characteristics of patients with WHO Group 3 PH are not well described.
To determine the clinical characteristics, hemodynamics, right ventricular (RV) function, and survival in patients with WHO Group 3 PH and to compare it to patients with pulmonary arterial hypertension (WHO Group 1).
We studied all patients with WHO Group 3 PH (n=98) and WHO Group 1 PAH (n=162) referred to our center. We used Kaplan-Meier method and Cox proportional hazard analysis to determine survival and independent predictors of mortality.
WHO Group 3 patients were older and had a higher proportion of males than Group 1 patients. When assessing invasively measured hemodynamics, Group 3 patients had lower mean pulmonary arterial pressures (40±10 vs. 45±14, p=0.002), lower pulmonary vascular resistance (7.5±3.4 vs. 10.5±6.4, p<0.001), and higher pulmonary arterial compliance (1.7±0.9 vs. 1.3±0.7, p<0.001) than Group 1 patients. However, Group 3 patients walked less on the six-minute walk test (237±112 vs. 332±140 meters, p<0.001) and had lower RV fractional area change (29±10% vs. 33±11%, p=0.024) when compared to Group 1 patients. Finally, group 3 PH had a worse survival when compared to Group I PAH (Figure 1).
Group 3 PH patients walked shorter distances, had more RV dysfunction, and worse survival despite having less severe pulmonary vascular disease when compared to Group 1 patients.