Aims Pulmonary hypertension (PH) in asymptomatic patients is a rare cause of sudden death. This study aims to determine the incidence of this entity and raise awareness among pathologists.

Methods We retrospectively investigated 44 cases of sudden unexpected death in relation to PH in patients not on antihypertensive therapy. This is the largest pathological study reported.

Results We report 44 cases of sudden death due to PH in which 28 (63.63%) were female and 16 (36.36%) were male, and the age range was from 5 days to 93 years old (mean age: 24±20). The majority had no clinical evidence of PH prior to death with none on therapy. The majority died at rest, 18 cases (40.90%), while 7 patients (15.90%) died following cardiac surgery and 7 patients (15.90%) during pregnancy or postpartum, 6 of whom had congenital heart disease. The cause of PH was recognised as congenital heart disease in 27 patients (61.36%), 14 of whom had simple congenital heart disease, such as atrial or ventricular septal defect,and 13 had complex congenital heart disease with associated atrial septal defect or ventricular septal defect. The remaining 17 patients (29.55%) suffered from primary PH due to plexiform arteriopathy, veno-occlusive disease and thromboembolic disease. Extensive sampling of the lungs is required to detect the lesions microscopically in these conditions.

Conclusions It is important that clinicians and pathologists be aware of the risk of sudden unexpected death in asymptomatic patients with PH, especially in those with congenital heart disease, after cardiac surgery or pregnancy.