Haemodynamic spectrum in heritable pulmonary arterial hypertension: a continuum from pre-capillary to combined pulmonary hypertension-case series.

Background: Heritable pulmonary arterial hypertension (PAH) is a rare form of pre-capillary pulmonary hypertension that typically affects young patients. With increased survival and subsequent ageing of these patients, newly acquired cardiovascular conditions may influence the pulmonary haemodynamic profile and impact management. Case summary: We report a case series of four patients with mutations in genes associated with PAH to illustrate the spectrum of pulmonary haemodynamics under the influence of superimposed acquired conditions. The first two cases involve patients with a long-standing diagnosis of heritable PAH and severe pre-capillary pulmonary hypertension, who developed overt left-sided diastolic dysfunction later in follow-up due to the acquisition of multiple cardiovascular comorbidities. The second two cases describe patients with a genetic pre-disposition to develop PAH and conditions that are risk factors for left heart disease, with mild elevation of resting pulmonary pressures, in whom exercise right heart catheterization unmasked occult left-sided diastolic dysfunction. Discussion: Pulmonary haemodynamics are complex and dynamic over time, even in patients with or at risk of heritable PAH, when additional acquired cardiovascular conditions emerge. Correct phenotyping at diagnosis and during follow-up of patients at risk of heritable PAH, along with a clear understanding of the underlying pulmonary haemodynamic profile, is crucial for appropriate management.