1350438 - Atrial Size and Function Predicts Right Ventricular Dysfunction After the Cone Operation for Ebstein Anomaly

Despite the improvement in outcomes after the cone operation for Ebstein anomaly, post-operative right ventricular dysfunction (RVD) is common. Previous studies have shown increased T1 by CMR in the left ventricle in Ebstein anomaly suggestive of diffuse myocardial fibrosis which likely impacts both systolic and diastolic ventricular function. Right atrial volume (RAV) in Ebstein anomaly likely reflects both the severity and duration of tricuspid regurgitation pre-cone, and the degree of diastolic dysfunction of the right ventricle (RV). In this study we sought to evaluate the role of preoperative CMR measures including atrial parameters in predicting RVD after the cone operation.

Methods:

This was a retrospective review of 23 consecutive patients who had a pre-cone operation CMR and postoperative echocardiogram. Automated biplane atrial function evaluation using offline analysis software ((CVi⁴², Circle Cardiovascular Imaging Canada) was performed to measure left atrial (LA) volumes and ejection fractions; contours were adjusted manually. The RAVs were measured from a standard 4 chamber SSFP cine. LA and RA maximal (end-systolic) and minimal (end-diastolic) volumes were calculated according to the biplane area-length and the single plane area-length method, respectively (Figure 1). The atrialized RV was not included in the RA contour, as the anatomic annulus defined the border of the RA.  Right and left ventricular volumes and ejection fractions were also computed from 4CH and short axis stacks, respectively, in the typical fashion. The Celermajer index and cartiothoracic index were calculated from the 4-chamber view in diastole² (Figure 2).  Finally, RVD presence was defined by at least moderate dysfunction by last echocardiogram. T-test was used to compare the groups with and without RVD.  

Results:

The median age at the cone operation was 17.9 years (interquartile range 7.2-30.8 years). The median follow-up to most recent echocardiogram was 9 months. Ten patients (43%) had postoperative RVD. Patients with postoperative RVD had a more dilated RV, lower LV ejection fraction and higher cardiothoracic ratio by preoperative cardiac CMR (table 1). Interestingly, there was no significant difference in RVEF between the postop RVD group and the group without RVD (p=0.09). Additionally, patients with postoperative RVD had a higher RA maximal volume (p=0.033), RA minimal volume (p=0.045) and a lower left atrial ejection fraction (p=0.048). There was no difference between the two groups in tricuspid regurgitant fraction on pre OP CMR. 

Conclusion:

Short and mid-term RVD is common after the cone operation and is associated with preoperative RV and right atrial dilation. Additionally, lower left atrial and left ventricular ejection fraction were associated with RVD suggesting a role for biventricular interaction. Preoperative CMR is an important tool to help predict patients who will develop postoperative RVD.  Further study is needed to understand long-term RV function changes.