[Pulmonary hypertension: pre- or post-capillary? The role of provocative tests in the cath lab]

The discrimination between heart failure with preserved ejection fraction (HFpEF) and pulmonary arterial hypertension (PAH) requires a multiparametric approach, eventually culminating in right heart catheterization. Solving this differential diagnosis is crucial in order to properly tailor patient treatment, with relevant clinical implications. However, it is not uncommon to be confronted with patients at intermediate or high risk of having HFpEF whose pulmonary artery wedge pressure (PAWP) falls in a grey zone in between 13 and 15 mmHg. In these patients, a provocative test in the cath lab might be considered, with the aim of unmasking an occult form of HFpEF with non-overt hemodynamic manifestations, or to definitely exclude it.Saline load and physical exercise can be viewed as the most suitable provocative tests seeking to help for the differential diagnosis in this specific patient population. Although normative values for the hemodynamic response to these maneuvers have been proposed, supporting evidence is still preliminary or equivocal. In this paper, we will review the pathophysiological background for the application of provocative tests in the cath lab, as well as methodological and interpretative aspects to discriminate between HFpEF and PAH, highlighting strengths and weaknesses of fluid load and physical exercise.