PAH-SDB: Sleep-Disordered Breathing and Outcomes in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive pulmonary vascular disease characterized by increased pulmonary vascular resistance, right ventricular dysfunction, and clinically important morbidity and mortality. Sleep-disordered breathing (SDB) and sleep-related hypoxemia are common in patients with PAH, but their prevalence, physiological determinants, longitudinal trajectories, prognostic significance, and potential role in individualized management remain incompletely defined. PAH-SDB is a prospective, multicenter, observational patient registry enrolling adults with right-heart-catheterization-confirmed World Health Organization Group 1 PAH at pulmonary vascular centers across China. Participants will undergo standardized nocturnal sleep and cardiorespiratory monitoring together with comprehensive PAH assessment, including clinical characteristics, functional status, biomarkers, echocardiography, hemodynamics, treatment, and outcomes. Selected participants may undergo additional polysomnography, cardiac magnetic resonance imaging, wearable monitoring, repeated sleep assessments, or biospecimen collection when available and ethically approved. The registry will characterize the prevalence and phenotypes of sleep-disordered breathing and nocturnal physiological abnormalities; examine their relationships with PAH severity and right ventricular-pulmonary vascular function; determine their value for predicting clinical worsening, hospitalization, transplantation, and mortality; evaluate longitudinal changes in sleep physiology in relation to PAH treatment and disease trajectory; and develop and validate multimodal statistical and artificial-intelligence models for phenotyping, risk prediction, and treatment-response stratification. Clinical management will remain at the discretion of treating physicians, and the registry will not assign PAH or sleep-related therapies.

Inclusion Criteria: * Age ≥18 years at enrollment. * Diagnosis of WHO Group 1 pulmonary arterial hypertension established by right heart catheterization using contemporary hemodynamic criteria: mean pulmonary artery pressure \>20 mmHg at rest, pulmonary arterial wedge pressure ≤15 mmHg, and pulmonary vascular resistance \>2 Wood units, with clinical classification consistent with Group 1 PAH. * PAH etiology may include idiopathic, heritable, drug/toxin-associated, connective-tissue-disease-associated, congenital-heart-disease-associated PAH after appropriate clinical classification, portal-hypertension-associated PAH, HIV-associated PAH, or other recognized Group 1 PAH subtypes. * Clinically stable enough to undergo overnight sleep/cardiorespiratory monitoring, as judged by the treating team. * Able and willing to provide written informed consent and participate in longitudinal follow-up. * Enrollment at a participating center with availability of the required baseline PAH dataset and a technically interpretable protocol-standardized sleep recording. Exclusion Criteria: * Pulmonary hypertension predominantly attributable to left heart disease (Group 2), lung disease and/or hypoxia (Group 3), chronic thromboembolic pulmonary hypertension or other pulmonary artery obstruction (Group 4), or unclear/multifactorial mechanisms (Group 5). * Pulmonary veno-occlusive disease / pulmonary capillary hemangiomatosis when the clinical phenotype is considered separately from conventional PAH for the planned analysis, unless the protocol intentionally includes this subgroup and prespecifies it as a distinct stratum. * Acute decompensated right heart failure, cardiogenic shock, severe active infection, or another acute condition that would make the baseline sleep recording unrepresentative or unsafe; these patients may be reconsidered after stabilization. * Current hospitalization primarily for an acute non-PAH illness likely to substantially distort nocturnal respiratory physiology. * Inability to obtain an adequate baseline sleep/cardiorespiratory recording after protocol-defined repeat attempt, unless the participant is retained in a registry-only stratum for non-sleep analyses. * Inability to provide informed consent or anticipated inability to complete meaningful follow-up. * Any other condition that, in the investigator's judgment, would prevent reliable study participation or data interpretation.