The RECONNECTIVE Registry is an observational single center study, focused on the subgroup of precapillary pulmonary hypertension related to connective tissue diseases. All patients will have hemodynamic confirmation by right heart catheterization and will be follow-up for at least 5 years from admission. All patients diagnosed with Group I Pulmonary Arterial Hypertension (PAH) associated with Connective Tissue Diseases (CTD) and Group IV Pulmonary Hypertension (PH) with CTD will be included. The purpose of the registry is to learn and understand the clinical outcomes and natural history of the pulmonary arterial hypertension in this subgroup of patients to improve the medical care and treatment.

Connective tissue diseases represents an important risk factor for pulmonary hypertension, either due to vasculopathy or chronic pulmonary thromboembolism. These chronic conditions are characterized by being disabling, progressive and fatal in a short time and are caused by multiple mechanisms that results in remodeling of the pulmonary microvasculature and right heart failure.

In recent years, due to international registries, we have acquired a better understanding of high-risk subpopulations, their poor prognostic factors, and the results of specific combination therapies. In Mexico, the National Institute of Medical Sciences and Nutrition Salvador Zubirán (INCMNSZ) is a referral center for connective tissue diseases and pathologies of the pulmonary circulation. The RECONNECTIVE registry is a five years follow-up cohort that offers the possibility to obtain data regarding to the clinical characteristics and hemodynamic assesment of pulmonary circulation. The main objective is to evaluate the clinical course of the PAH in this subgroup of patients and their specific therapy for PAH.

Inclusion Criteria:

• Incident and prevalent patients diagnosed with Group I associated with Connective Tissue Diseases (CTD)
• Incident and prevalent patients diagnosed with Group IV Pulmonary Arterial Hypertension (PAH) associated with Connective Tissue Diseases (CTD) with evidence of a chronic thromboembolic pulmonary disease by ventilation/perfusion pulmonary gammagraph or computed tomography pulmonary angiogram with at least three months of total anticoagulation therapy.
• Patient diagnosed with a connective tissue disease according to the classification criteria of the American College of Rheumatology.
• Precapillary pulmonary hypertension confirmed by right heart catheterization (RHC): Mean pulmonary arterial pressure (mPAP) >20 mm Hg with a pulmonary arterial wedge pressure ≤ 15 mm Hg and Pulmonary vascular resistance (PVR) ≥ 2.0 Wood units

Exclusion Criteria:

• Patients who meet the criteria for another group of pulmonary hypertension (Groups II, III or V).

Patients with Group I Pulmonary Arterial Hypertension (PAH) associated to Connective Tissue Diseases (CTD) and Group IV Pulmonary Hypertension group (PH) with CTD.