Distinction Between Precapillary and Postcapillary Pulmonary Hypertension by the Atrial Volume Ratio on Transthoracic Echocardiography

Objectives The differential diagnosis between precapillary and postcapillary pulmonary hypertension (PH) is important for deciding on the appropriate therapeutic strategy. The aim of this study was to assess whether the atrial volume ratio can differentiate precapillary and post-capillary PH. Methods Seventy-seven patients with PH who underwent transthoracic echocardiography (TTE) and right heart catheterization were retrospectively studied. Pulmonary hypertension was defined as a mean pulmonary arterial pressure of 25 mm Hg or higher by right heart catheterization. Patients with a pulmonary capillary wedge pressure higher than 15 mm Hg were classified as having postcapillary PH, and patients with a pulmonary capillary wedge pressure of 15 mm Hg or lower were classified as having precapillary PH. The atrial volume ratio derived from TTE was defined as right atrial volume divided by left atrial volume. Results Forty-four (57%) of 77 patients had precapillary PH by the right heart catheterization classification. The atrial volume ratio was significantly higher in precapillary PH than in postcapillary PH (1.03 ± 0.69 versus 0.50 ± 0.19; P