**Introduction / Hypothesis**
Tricuspid regurgitation (TR) is associated with increased mortality and poor prognosis. Novel investigational transcatheter tricuspid valve (TV) repair/replacement devices have the potential to address a large unmet need in TR patients. Cardiac computed tomography (CT) is the reference standard for determining patient eligibility and accurate device sizing for transcatheter TV therapies. However, 3-dimensional transthoracic echocardiography (3D TTE) is more widely available and recent advances have enhanced 3D visualization of the tricuspid valve and tricuspid annulus (TA). We aimed to compare TA dimensions by 3D TTE using a semi-automated measurement package versus the reference standard CT

**Methods**
We retrospectively identified 37 patients with severe TR that underwent 3D TTE and CT chest angiogram for workup of possible transcatheter tricuspid intervention from 2021 to 2023. 3D TTE datasets were obtained from the tricuspid inflow and apical 4-chamber right ventricular-focused views. TA dimensions were measured by two independent readers (AD, JJT) blinded to the CT measures using an automated software package (4D autoTVQ, GE EchoPAC version 204).  CT images were obtained using retrospective electrocardiographic gating and the TA was measured using Circle Cardiovascular Imaging (cvi42) software. We tested agreement of CT with 3D TTE for a TA maximum diameter >55 mm versus ≤55 mm, which is near the upper threshold of tricuspid annular size for some current investigational tricuspid devices and a recently FDA-approved transcatheter tricuspid valve replacement device (EVOQUE valve, Edwards Lifesciences).

**Results**
Mean age was 80±7 years and 59% were female. Mean TA maximum diameter was 48.5±6.7 mm by 3D TTE and 48.7±7.0 mm by CT (p=0.64); mean difference was -0.2 mm (95% confidence interval -6.2, 5.7) and correlation was good (R=0.90, p<0.001). Mean TA area was 16.9±5.0 cm2 by 3D TTE and 17.3±4.8 cm2 by CT (p=0.08); mean difference was -0.4 cm2 (95% confidence interval -2.7, 2.0) and correlation was good (R=0.97, p<0.001). Mean TA perimeter was 146.7±20.6 mm by 3D TTE and 148.9±19.7 mm by CT (p=0.02); mean difference was -2.2 mm (95% confidence interval -12.9, 8.5) with good correlation (R=0.96, p<0.001).  Maximum TA diameter was ≤55 mm by CT was present in 32 patients and 3D TTE maximum diameter was ≤55 mm in 31 of these patients (96%). Maximum TA diameter was >55 mm by CT was present in 5 patients, agreement by 3D TTE was present in 4 of these patients (80%).

**Conclusion**
3D TTE slightly underestimates TA dimensions when compared to CT, but correlation was excellent for all three measurements.  There was good agreement for a maximum TA diameter >55 mm versus <55 mm (35/37, 95%). We feel our data suggest 3D TTE has potential for use as a screening tool in TR patients considered for transcatheter valve replacement. 3D TTE may be sufficient in some cases to identify patients with an annulus that is too large for available valve replacement devices, thus obviating the need for CT imaging in this subset.



**Introduction / Hypothesis**
Tricuspid regurgitation (TR) is associated with increased mortality and poor prognosis. Novel investigational transcatheter tricuspid valve (TV) repair/replacement devices have the potential to address a large unmet need in TR patients. Cardiac computed tomography (CT) is the reference standard for determining patient eligibility and accurate device sizing for transcatheter TV therapies. However, 3-dimensional transthoracic echocardiography (3D TTE) is more widely available and recent advances have enhanced 3D visualization of the tricuspid valve and tricuspid annulus (TA). We aimed to compare TA dimensions by 3D TTE using a semi-automated measurement package versus the reference standard CT

**Methods**
We retrospectively identified 37 patients with severe TR that underwent 3D TTE and CT chest angiogram for workup of possible transcatheter tricuspid intervention from 2021 to 2023. 3D TTE datasets were obtained from the tricuspid inflow and apical 4-chamber right ventricular-focused views. TA dimensions were measured by two independent readers (AD, JJT) blinded to the CT measures using an automated software package (4D autoTVQ, GE EchoPAC version 204).  CT images were obtained using retrospective electrocardiographic gating and the TA was measured using Circle Cardiovascular Imaging (cvi42) software. We tested agreement of CT with 3D TTE for a TA maximum diameter >55 mm versus ≤55 mm, which is near the upper threshold of tricuspid annular size for some current investigational tricuspid devices and a recently FDA-approved transcatheter tricuspid valve replacement device (EVOQUE valve, Edwards Lifesciences).

**Results**
Mean age was 80±7 years and 59% were female. Mean TA maximum diameter was 48.5±6.7 mm by 3D TTE and 48.7±7.0 mm by CT (p=0.64); mean difference was -0.2 mm (95% confidence interval -6.2, 5.7) and correlation was good (R=0.90, p<0.001). Mean TA area was 16.9±5.0 cm^2^ by 3D TTE and 17.3±4.8 cm^2^ by CT (p=0.08); mean difference was -0.4 cm^2^ (95% confidence interval -2.7, 2.0) and correlation was good (R=0.97, p<0.001). Mean TA perimeter was 146.7±20.6 mm by 3D TTE and 148.9±19.7 mm by CT (p=0.02); mean difference was -2.2 mm (95% confidence interval -12.9, 8.5) with good correlation (R=0.96, p<0.001).  Maximum TA diameter was ≤55 mm by CT was present in 32 patients and 3D TTE maximum diameter was ≤55 mm in 31 of these patients (96%). Maximum TA diameter was >55 mm by CT was present in 5 patients, agreement by 3D TTE was present in 4 of these patients (80%).

**Conclusion**
3D TTE slightly underestimates TA dimensions when compared to CT, but correlation was excellent for all three measurements.  There was good agreement for a maximum TA diameter >55 mm versus <55 mm (35/37, 95%). We feel our data suggest 3D TTE has potential for use as a screening tool in TR patients considered for transcatheter valve replacement. 3D TTE may be sufficient in some cases to identify patients with an annulus that is too large for available valve replacement devices, thus obviating the need for CT imaging in this subset.



Comparison of Tricuspid Annulus Dimension Measurements Using Automated Three-Dimensional Transthoracic Echocardiography and Computed Tomography in Patients Evaluated for Transcatheter Tricuspid Valve Intervention