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.