Who’s Who of Pulmonary Hypertension
Redefining Classification to Advance Precision Care
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See Article by Zhu, Gonzaga-Jauregui, and Welch et al
Since inception in 1973, the World Health Organization group classification system for pulmonary hypertension (PH) has provided researchers and clinicians an evolving framework from which to investigate, diagnose, and treat patients with a diverse collection of pulmonary vascular diseases.1 The original schema distinguished primary PH from secondary; primary encompassing contemporary classifications of idiopathic, familial, and drug-induced PH.2 A second form took the general shape recognized by present-day practitioners: defining World Health Organization groups 1 to 5 based on similarities in pathological findings, hemodynamic characteristics, and management.1 Subsequent iterations have maintained a comparable structure with additions and changes paralleling scientific advancement. The definitions are widely accepted worldwide, and consequently used daily in practice by clinicians, as inclusion/exclusion criteria for clinical research, and in the labeling of new therapeutics for the treatment of PH.
The disorders comprising World Health Organization group 1 or pulmonary arterial hypertension (PAH) are characterized by an arterial vasculopathy of the pulmonary circulation, with mutual features including luminal obliteration, loss of distal arterioles, and endothelial dysfunction with prominent vasoconstriction.3 Although the entities in group 1 PAH share a common final pathology, ongoing research has …