Epidemiology of pulmonary hypertension in the elderly

Pulmonary hypertension (PH) is a haemodynamic and pathophysiological condition defined as increase in mean pulmonary arterial pressure ≥ 25 mmHg at rest as assessed by right heart catheterization (RHC). It can be due to a primary elevation of pressure in the pulmonary arterial system alone (pulmonary arterial hypertension), or secondary to elevations of pressure in the pulmonary venous and capillary systems (pulmonary venous hypertension). PH can be a progressive, fatal disease if untreated, although the rate of progression is highly variable. The clinical classification of PH is intended to categorize multiple clinical conditions into five groups according to their similar clinical presentation, pathological findings, and haemodynamic characteristics. Pulmonary arterial hypertension (PAH) describes group 1, while pulmonary hypertension (PH) describes group 2 through group 5. Group 1: PAH. PAH is a clinical condition characterized by the presence of pre-capillary PH and pulmonary vascular resistance (PVR) > 3 Wood units, in the absence of other causes of pre-capillary PH such as PH due to lung diseases, chronic thromboembolic PH, or other rare diseases. It consists of sporadic idiopathic PAH (iPAH), heritable PAH (also known as familial PAH), and PAH associated (aPAH) with drugs and toxins, connective tissue diseases (CTD), human immunodeficiency virus (HIV) infection, portal hypertension, congenital heart disease (CHD), and schistosomiasis. Group 2: PH due to left heart disease (PH-LHD). PH due to LHD is characterized PH associated with an elevated left atrial and pulmonary venous pressure. PH due to left ventricular (LV) systolic or diastolic dysfunction, valvular heart disease, inflow/outflow tract obstruction, congenital cardiomyopathies and pulmonary veins stenosis are included in this group. Group 3: PH due to lung diseases and/or hypoxia. PH due to lung diseases and/or hypoxemia includes PH due to chronic obstructive pulmonary disease (COPD), interstitial lung disease, other pulmonary diseases with mixed restrictive and obstructive pattern, sleep-disordered breathing, alveolar hypoventilation disorders, and other conditions associated with hypoxemia. The underlying lung disease in this group as a whole is usually severe. Group 4: chronic thromboembolic PH (CTEPH) and other pulmonary artery obstructions. Chronic thromboembolic PH is due to chronic thromboembolic occlusion of the proximal or distal pulmonary vasculature. Pulmonary hypertension in this group has the potential for improvement or cure with pulmonary thromboendarterectomy. Group 5: pulmonary hypertension with unclear and/or multifactorial mechanisms. Pulmonary hypertension with unclear and/or multi-factorial mechanisms included patients with PH caused by chronic hemolytic anemia [e.g., sickle cell disease (SCD), beta-thalassemia, or spherocytosis], myeloproliferative disorders, systemic disorders (e.g., sarcoidosis), metabolic disorders (e.g., glycogen storage disease), chronic kidney disease, or miscellaneous causes. PH is, in general, an uncommon manifestation of these disorders.