Abstract Body (Do not enter title and authors here): Background
Staged palliation process for single ventricle (SV) patients alters preload, afterload, and ventricular mechanics, making accurate function assessment essential. Left ventricular echocardiography markers have been applied to SV patients such as ejection fraction (EF), though reliability is limited. Continuous wave Doppler (CWD)-derived dp/dt during isovolumetric contraction has surfaced as a potential non-geometric contractility index.

Hypothesis
We predicted that CWD-derived dp/dt would correlate with cardiac magnetic resonance (CMR) -derived EF in adults with SV physiology.

Methods
This was a single-center retrospective study of SV patients ≥18 at the Ahmanson/UCLA between 2010-2024. Inclusion required echo and CMR with volumetrics within one year. We measured dp/dt by obtaining the time interval that AV regurgitation velocity increased from 1 to 3 m/s. Correlation, linear regression, and ROC analysis were performed.

Results
A total of 71 patients met inclusion criteria. Median age of 28.9 years (IQR: 23.6, 34.5), and 41 (57.8%) were female. 37 (52%) had a single left ventricle (LV), 30 (42.3%) had a single right ventricle, and 4 (5.6%) had mixed morphology. AV-valve regurgitation was classified as trace in 13 (25.3%), mild 37 (52.2%), moderate (25.4%), and severe 1 (1.6%). Median time between CMR and echo study was 13 days (IQR: -2, 64). Median CMR EF was 51%, with no significant difference by ventricular morphology (p=0.15). Median dp/dt was 803 mmHg/sec and did not significantly differ between right and left ventricle (p=0.09). Linear regression showed no association between dp/dt and CMR EF (p=0.1); however, with nEDV as a correction factor, correlation improved (β=0.025, p=0.007). The coefficient for the interaction term between dp/dt and nEDV was -0.0002 (p=0.025) which means that the association between dp/dt becomes stronger as nEDV decreases. ROC analysis revealed that qualitative echocardiogram assessment by experienced ACHD cardiologists (AUC 0.77) outperformed dp/dt (AUC 0.55-0.62) in identifying moderate-severe dysfunction.

Conclusions
We demonstrate that echo CWD derived dp/dt has poor ability in distinguishing between mild and moderate/severe systolic SV dysfunction on CMR in ACHD patients. Even with adjustment for nEDV, dp/dt should not be used as an objective parameter to evaluate SV function. Our study shows that careful assessment by well-trained ACHD cardiologists is more sensitive in determining significant SV dysfunction.