What is the correct classification for a patient with pulmonary arterial hypertension demonstrated by elevated mPAP and normal left-sided filling pressures?

In this scenario, the classification of pulmonary arterial hypertension (PAH) is based on specific hemodynamics and the underlying causes of the condition. When a patient demonstrates elevated mean pulmonary artery pressure (mPAP) alongside normal left-sided filling pressures, this indicates that the pulmonary hypertension is related specifically to the pulmonary arteries rather than being a consequence of left heart pathology.

The classification of pulmonary hypertension is outlined by the World Health Organization (WHO) and is divided into five groups. Group 1 is specifically identified as pulmonary arterial hypertension, which encompasses idiopathic PAH, heritable PAH, drug-induced PAH, and PAH associated with other conditions such as connective tissue disease, HIV infection, and others. The key feature of this classification is that the elevated pressures occur due to primary changes in the pulmonary vasculature.

In contrast, Group 2 pulmonary hypertension is associated with left heart disease; Group 3 includes pulmonary hypertension secondary to chronic lung diseases or hypoxia; Group 4 refers to pulmonary hypertension caused by chronic thromboembolic processes; and Group 5 encompasses all other forms, including those with multifactored etiologies.

Given the provided hemodynamic parameters—elevated mPAP and normal left-sided filling pressures—