Abstract 18195: Relationship Between Echocardiographic and MRI-derived Measures of RV Size and Function in Patients with Pulmonary Arterial Hypertension

Abstract

Objectives: The right ventricle (RV) is a chamber with complex geometry that is difficult to visualize on transthoracic echocardiography (TTE). TTE parameters have been established to estimate the RV systolic function, but validation in pulmonary hypertension patients is limited. We aim to evaluate two commonly used parameters, tricuspid annular plane systolic excursion (TAPSE) and fractional area change (FAC) by both MRI and TTE and compare with the MRI-derived “gold standard” RV ejection fraction (RVEF).

Methods: Cardiac MRI and TTE images were acquired in 42 consecutive patients with pulmonary hypertension referred for cardiac MRI. TTE images were acquired within a 1-week interval for 36/42 and within 2 months for 6/42. MRI and TTE measurements were made by independent observers. MRI images were analyzed using commercially available software and RVEF calculated using volumes derived from short axis images at end-diastole and end-systole, defined by the largest and smallest RV volume, respectively. For both MRI and TTE, TAPSE was measured on 2D 4-chamber images and FAC was calculated from the end-diastolic and end-systolic areas of the RV on 2D 4-chamber images. Trabeculations were excluded on all area and volume measurements for both TTE and MRI.

Results: There was excellent agreement between MRI and TTE measurements, with Pearson’s correlation coefficient of r=0.96 for FAC and r=0.85 for TAPSE. Evaluating RV size, MRI end-diastolic volume correlated well with RV area by MRI, r=0.92, and RV area by TTE, r=0.88. With regard to function, MRI-derived “gold standard” EF correlated best with MRI-derived FAC, r=0.83, and TTE-derived FAC, r=0.85. RVEF did not correlate as well with MRI-derived TAPSE, r=0.7, or TTE-derived TAPSE, r=0.8. P-value is <0.0001 for all.

Conclusions: Echocardiographic estimates of RV volume, by end-diastolic area, and function, by FAC and TAPSE are accurate in patients with pulmonary hypertension, with FAC being more accurate than TAPSE.