Introduction: Pulmonary arterial hypertension (PAH) is a progressive, fatal disease associated with non-specific symptoms, which may lead to diagnosis delays and poor outcomes. Research Question: Which symptoms and diagnostic procedures occur prior to PAH diagnosis and do they vary based on diagnosis delay? Aim: To describe PAH symptoms and diagnostic procedures among patients newly diagnosed with PAH. Methods: Adults with PAH were identified from Optum’s de-identified Clinformatics ® Data Mart Database (2016-2021). Eligible patients had continuous health plan enrollment ≥12 months (mo) before the first recorded PAH-related symptoms (i.e., index date ) and from the index date until the first recorded PAH diagnosis on a medical claim (i.e., study period ). Patients also had ≥1 fill for a PAH treatment and ≥1 right heart catheterization at any time post-index. PAH symptoms and diagnostic procedures were described during the study period, overall, and stratified by time between the index date and first PAH diagnosis (i.e., diagnosis delay ; ≤12 mo, 12–24 mo, and >24 mo). Results: The sample included 538 patients (≤12 mo: N=327; 12–24 mo: N=126; >24 mo: N=85). Mean age was 66 years, 60.6% were female, and mean (range) diagnosis delay was 11.8 (0.0–50.2) mo. During the study period, most patients had ≥2 unique symptoms recorded, but those with longer delay had more fatigue (≤12 mo: 26.6%; 12–24 mo: 55.6%; >24 mo: 54.1%), edema (29.1%; 42.9%; 51.8%), and dizziness (10.1%; 23.0%; 18.8%), among others. Mean delay was shorter when the first symptoms were ascites (4.2 mo) and syncope (6.4 mo) and longer for fatigue (14.2 mo) and dizziness (14.0 mo). On average, patients with longer delay had more diagnostic procedures pre-diagnosis (≤12 mo: 4.3; 12–24 mo: 8.2; >24 mo: 8.7), driven by more electrocardiograms (ECG; 1.9; 4.2; 4.5). Overall, 85.5% of patients had an ECG and 83.5% had a transthoracic echocardiography pre-diagnosis. Conclusions: Symptoms such as fatigue, edema, and dizziness were more common in patients with longer time to diagnosis and these patients had more diagnostic procedures. Greater physician awareness and new screening tools (e.g., predictive algorithms using ECG data) could accelerate PAH diagnosis and treatment aiming at improving patient outcomes.