Use of Handheld Ultrasound to Estimate Right Atrial Pressure in a Pulmonary Hypertension Clinic

Rationale: Point-of-care ultrasonography is an invaluable asset for inpatient decision-making. Whether handheld ultrasound can be used in the outpatient management of pulmonary hypertension 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 outpatients with pulmonary hypertension. Methods: This prospective study included outpatients in a Pulmonary Hypertension Comprehensive Care Center clinic who had a same-day BNP concentration. We used a handheld ultrasound to measure inferior vena cava 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 with BNP at baseline and over time. Cox regression was used to determine whether these measurements were associated with time to clinical worsening. Results: Ninety patients (60% Group 1 pulmonary hypertension) were enrolled. Patients with an intermediate or high eRAP category at baseline had higher BNP concentrations 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% confidence interval [CI], 84-227). Higher baseline eRAP category was independently associated with more than twofold increased risk for clinical worsening (hazard ratio, 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 pulmonary hypertension clinics. Clinical trial registered at clinicaltrials.gov (NCT02873039).