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RATIONALE Point-of-care ultrasonography is an invaluable asset for inpatient decision-making. Whether handheld ultrasound can be utilized in the outpatient management of pulmonary hypertension (PH) is unknown. OBJECTIVES We investigated whether a handheld ultrasound estimate of right atrial pressure correlates with B-type natriuretic peptide (BNP) and clinical outcome over time in PH outpatients. METHODS This prospective study included outpatients in a PH Comprehensive Care Center clinic who had a same-day BNP level. We used a handheld ultrasound to measure inferior vena cava (IVC) size and collapsibility, which were used to estimate right atrial pressure (eRAP) and categorize it as normal, intermediate, or high. Correlation analysis was used to compare these ultrasound measurements to BNP at baseline and over time. Cox regression was used to determine if these measurements were associated with time to clinical worsening. RESULTS Ninety patients (60% Group 1 PH) were enrolled. Patients with an intermediate or high eRAP category at baseline had higher BNP levels than patients with normal eRAP. For every transition in eRAP category (e.g. from normal to intermediate) between clinic visits, BNP changed by an average of 155 pg/mL (95% CI 84 to 227). Higher baseline eRAP category was independently associated with more than two-fold increased risk for clinical worsening (HR 2.44, 95% CI 1.47-4.07). CONCLUSIONS Right atrial pressure estimated by portable handheld ultrasound correlates with BNP at baseline and serially over time. Furthermore, eRAP is independently associated with clinical worsening. The use of portable handheld ultrasound to estimate right atrial pressure should be considered in PH clinics. Clinical trial registered at clinicaltrials.gov (NCT02873039).