Prognostic value and diagnostic properties of the diastolic pulmonary pressure gradient in patients with pulmonary hypertension and left heart disease.

Background: The use of the diastolic pressure gradient (DPG) for the diagnosis of combined post- and pre-capillary pulmonary hypertension (Cpc-PH) versus isolated post-capillary pulmonary hypertension (Ipc-PH) in patients with PH due to left heart disease (PH-LHD) remains controversial. We studied the incremental prognostic information provided by DPG and potential sources of disagreements between different hemodynamic criteria for Cpc-PH.

Methods: We studied 393 patients with PH-LHD who underwent right heart catheterization and were followed for hospitalizations and all-cause mortality for a median of 53 months. Patients were classified into Ipc-PH or Cpc-PH using DPG, pulmonary vascular resistance (PVR) or transpulmonary gradient (TPG)-based criteria.

Results: Classifying PH categories according to DPG alone was not associated with a significant difference in clinical outcomes between patients with Ipc-PH and Cpc-PH (P = 0.17). By contrast, PVR criteria alone were associated with a strong prognostic separation between Ipc-PH and Cpc-PH (P = 0.005). Adding DPG to the PVR-based classification contributed no additional prognostic information. Classifying PH using the cutoff of DPG >7 mmHg or TPG >15 mmHg, resulted in an almost perfect agreement (κ statistic 0.87; 93.4% agreement). However, in cases of disagreement, occurring with low or negative DPG values, the TPG-based classification was more likely to be correct.

Conclusion: The DPG does not add incremental prognostic information beyond PVR. Using DPG/PVR criteria to differentiate between Ipc-PH and Cpc-PH is equivalent to using TPG/PVR criteria with a TPG threshold >15 mmHg. However, the use of DPG for diagnostic purposes may lead to misclassification of PH when DPG is low or negative.