Prognostic value of cardiac CT parameters in patients undergoing surgical correction for tricuspid regurgitation: a prospective study

Introduction

The association of tricuspid regurgitation (TR) severity with survival and the development of transcatheter tricuspid valve (TV) intervention has increased the focus on TV disease since several decades (1). Approximately 80% of significant TR cases are functional and associated with TV annular dilation and leaflet tethering in pressure and/or volume overload-related right ventricular (RV) remodeling (2). The 2020 American Heart Association/American College of Cardiology guideline for the management of patients with valvular heart disease includes TR severity and other factors, such as tricuspid annulus diameter (TAD), RV function, and pulmonary hypertension, as indications for TR intervention (3), and these should be included in imaging evaluation of TV disease.

Echocardiography is the primary investigation for assessing TV disease; however, multimodality imaging is preferred for comprehensive evaluation because cardiac magnetic resonance (CMR) imaging and computed tomography (CT) are complementary investigations to echocardiography (4). Compared to echocardiography, CMR provides a more accurate, reproducible assessment of RV volumes, systolic function, and other parameters, including TAD and the degree of leaflet tethering. Cardiac CT enables better anatomic visualization of TV apparatus and adjacent structures, thereby enabling transcatheter therapy planning (5). In case of arrhythmia and poor compliance, CMR image quality is often impaired; thus, cardiac CT constitutes a useful modality for RV functional evaluation.

A retrospective study demonstrated that preoperative cardiac CT-based TAD and RV volumes could predict immediate postoperative RV dysfunction (<7 days) after TV surgery (6). Nevertheless, the predictive value of perioperative cardiac CT parameters, including not only TAD and RV volume on preoperative CT but also the extent of postoperative RV volume decrease, for long-term postoperative outcomes is unclear. Therefore, we hypothesized that TAD and RV volume parameters measured on cardiac CT and the postoperative RV volume change could be associated with postoperative adverse outcomes after TV surgery.

The purpose of our study was to prospectively investigate the prognostic value of perioperative CT-derived TV annular and RV parameters in long-term postoperative adverse outcomes after TV surgery. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2024-2915/rc).

Methods

Patients

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This prospective study was approved by the Institutional Review Board of Severance Hospital (No. 4-2018-0725) and informed consent was taken from all individual participants.

We prospectively enrolled patients who met all the following criteria: (I) received TV surgery between June 2019 and January 2021; (II) underwent cardiac CT before TV surgery; (III) did not receive concomitant coronary artery bypass-grafting with TV surgery; and (IV) informed consent for study participation. The exclusion criteria included: (I) serum estimated glomerular filtration rate <60 mL/min/1.73 m²; (II) history of TV surgery before preoperative CT (Figure 1). Of the 84 eligible patients, 13 were excluded: two had decreased serum estimated glomerular filtration rate on follow-up study before the postoperative CT examination, 11 withdrew consent. Therefore, 71 patients underwent postoperative cardiac CT at 6 months after TV surgery. Among these 71 patients, five patients were excluded from analysis because four patients had primary TR etiology, and one patient had inadequate CT image quality for RV assessment. In total, 66 patients (36 women and 30 men; mean age 62.0±13.3 years) were included in the final analysis.

Figure 1 Flow chart of patient enrollment in this study. CT, computed tomography; TV, tricuspid valve.

CT acquisition protocol

At our institution, cardiac CT is routinely performed to evaluate coronary artery and intra-/extracardiac structures before scheduling patients with valvular heart disease to receive valve surgery. All preoperative and postoperative CT scans were performed with a wide-coverage, 256-row (16 cm in the z-axis) CT scanner (Revolution CT, GE Healthcare, Waukesha, WI, USA) with a tube rotation time of 280 ms (temporal resolution 140 ms). Patients were not premedicated with an oral beta-blocker for heart-rate control, and all CT angiography examinations were performed with prospective electrocardiogram-gating and single-beat acquisition (padding range of 20–120% of the R-R interval) to cover the whole cardiac cycle and alleviate the stair-step artifact (7,8). The triple-phase injection method (70 mL iopamidol, followed by 30 mL 50% blended iopamidol with saline, and 20 mL saline at 5 mL/s flow rate) was used to achieve sufficient RV enhancement. Scan delay times from contrast agent injection to scanning were determined individually using the bolus-tracking technique with a region-of-interest in the ascending aorta. All images were reconstructed with soft-tissue kernels and slice thickness of 0.625 mm, with 0.625-mm increments. Ten transverse datasets were reconstructed every 10% of the cardiac cycle and transferred to an image server for analysis using dedicated software (Aquarius iNtuition, Ver. 4.4.11, TeraRecon, San Mateo, CA, USA). The mean dose-length products of preoperative and postoperative cardiac CT were 257.3±71.4 and 310.4±78.2 mGy·cm, respectively.

CT image analysis

All CT analyses were performed by a cardiac radiologist, blinded to clinical information and echocardiographic results. On both preoperative and postoperative cardiac CT scans, RV volume was quantified with a semiautomatic three-dimensional region-growing method, both in end-diastolic and end-systolic phases (Figure 2) (9,10). The endocardial border was delineated using an attenuation-based thresholding method, with manual threshold adjustment until the appearances matched the visual assessment. Papillary muscles and trabeculations were excluded from the RV volume. End-diastolic and end-systolic volumes (EDV and ESV) were measured, and stroke volume (SV) was calculated as [EDV−ESV]. The RV ejection fraction (RVEF) was defined as “SV/EDV”.

Figure 2 A representative case in a 73-year-old female for measurement of RV volume using cardiac CT. (A,B) The RVEDV/BSA was measured at 261.66 mL (201.3 mL/m²) on preoperative cardiac CT, which was taken 5 days prior to the surgery. She had been diagnosed with prosthetic mitral valve dysfunction, native aortic valve steno-regurgitation, and severe TR. She subsequently underwent tricuspid valve repair using an annuloplasty ring, along with a redo-mitral valve replacement and aortic valve replacement. (C,D) Postoperative cardiac CT showed a decrease in RV volume [RVEDV 177.86 mL (134.7 mL/m²)], resulting in postoperative RVEDV change of −33.0%. On postoperative follow-up echocardiography at 7 months, she had a moderate residual TR and right ventricular systolic pressure of 42 mmHg. (A,C) Axial CT images (RV cavity in green) and (B,D) 3-dimensional volume rending images depict RV volume measurement. BSA, body surface area; CT, computed tomography; EDV, end-diastolic volume; RV, right ventricle; TR, tricuspid regurgitation.

Preoperative TV assessment comprised TAD measurement on multiplanar reformatted images in diastole showing maximal dimensions, as follows: (I) maximal diameter on four-chamber view (TAD_4ch); (II) maximal diameter on long-axis view (TAD_LA); and (III) average diameter derived from the TV annulus area on en-face (short-axis) view (TAD_avg) (6,11). For TAD and RV volume parameters, values indexed by body surface area (BSA) were analyzed. Postoperative RV volume changes were calculated for RVEDV/BSA, RVESV/BSA, RVSV/BSA as follows: 100 × (RV volume_post − RV volume_pre)/RV volume_pre. The RVEF change was calculated as RVEF_post − RVEF_pre.

Echocardiographic parameters

All patients underwent preoperative echocardiography (transthoracic or transesophageal echocardiography) within a median duration of 11 days (25^th to 75^th percentile, 2.8–34.0 days) from their TV surgery and underwent 6-month follow-up transthoracic echocardiography postoperatively at a median duration of 192.0 days (25^th to 75^th percentile, 183.0–199.0 days). Thereafter, further follow-up transthoracic echocardiography was performed annually or bi-annually. TR severity was graded semi-quantitatively from color and continuous-wave Doppler data using a multiparametric approach: none or trivial (0–1+), mild (2+), moderate (3+), or severe (4+) (12,13). Preoperative TAD was measured in end-diastole in the apical four-chamber view (TAD_echo) (12). The RV systolic pressure (RVSP) was calculated from the maximum velocity of the TR jet on transthoracic echocardiography according to the modified Bernoulli equation (14).

TV surgery

TV surgery, indicated according to the current guideline (3), was performed by one of two experienced cardiothoracic surgeons. In detail, TV surgery was indicated for severe TR undergoing left-sided valve surgery, or non-severe but progressive TR undergoing left-sided valve surgery with (I) TAD dilatation (tricuspid annulus end-diastolic diameter >40 mm or 21 mm/m²) on echocardiography or CT or (II) prior signs or symptoms from right-sided heart failure (3). Isolated TV surgery was considered in patients with signs and symptoms of right-sided heart failure and severe isolated secondary TR attributable to annular dilation (in the absence of pulmonary hypertension or left-sided disease) who are poorly responsive to medical therapy (3). In general, ring annuloplasty of TV was performed using either semi-rigid ring with flexible ends (Tri-AD; Medtronic, Minneapolis, MN, USA) or rigid (MC3; Edwards LifeScience, Irvine, CA, USA). In case of non-repairable valve morphology such as severe leaflet thickening and calcification, TV replacement was performed. During operation, the decision to occlude left atrial appendage was made in cases with persistent atrial fibrillation at the discretion of the surgeon, using one of following two methods: closure with an internal ligation method or amputation with a stapler device.

Data analysis

Clinical data were collected from medical records until the clinical follow-up end date of April 30, 2022 (mean postoperative follow-up period 597.9±182.2 days). Preoperative echocardiographic data included TR severity, TAD_echo, RVSP, and left ventricular ejection fraction. Postoperative follow-up transthoracic echocardiography data at least 6 months or later after surgery included residual TR severity and RVSP. In cases with preoperative TR with moderate to severe degree, type of TR was classified into atrial secondary functional TR and ventricular secondary functional TR, according to the recent proposed criteria (15). There was no cardiac implantable electronic device-related TR in our study population.

Study endpoint

The primary endpoint was the postoperative adverse outcome, including death from any cause, unplanned postoperative admission within postoperative follow-up period, or residual TR, or elevated RVSP >50 mmHg on postoperative transthoracic echocardiography after discharge (at least 6 months or later after TV surgery).

Statistical analysis

Statistical analyses were performed using computerized statistics programs (MedCalc for Windows, version 20.106; MedCalc Software, Mariakerke, Belgium, and R version 4.2.1, R Foundation for Statistical Computing, Vienna, Austria). Normally distributed data were identified using the Shapiro-Wilk W test. Continuous variables were presented as mean ± standard deviation and were compared using the independent t-test for normally distributed data or the Mann-Whitney U test for non-normally distributed data. Comparison of clinical, CT, and echocardiographic variables between patients with and without postoperative adverse outcomes was performed using the Chi-squared or Fisher’s exact test for categorical variables, or the independent t-test or Mann-Whitney U test for continuous variables. Cumulative event rates were investigated by the Kaplan-Meier curve. Cutoffs of echocardiography or CT-derived parameters for comparison of survival curve were set by maximally selected rank statistics. Intergroup differences in event-free survival time were compared using the log-rank test. Restricted mean survival time was compared between groups at postoperative timepoints of 1 and 2 years. Cox proportional hazard regression analyses were performed to identify significant prognostic factors for postoperative adverse outcomes. Hazard ratios with 95% confidence intervals were used to ascertain risk estimations for unadjusted and adjusted analyses of clinical variables. Proportional hazard assumption of each variable was assessed using Schoenfeld residuals (16). Associations of postoperative volume change between clinical, echocardiographic, and CT parameters were assessed using logistic regression analysis. Probability values <0.05 were considered statistically significant.

Results

Baseline characteristics

Baseline clinical characteristics are summarized in Table 1. All patients received TV repair (ring annuloplasty) except one patient who underwent TV replacement due to severe leaflet thickening calcification. Three (4.5%) patients underwent isolated TV surgery: one due to secondary TR following prior left-sided valve correction and two due to atrial functional TR associated with atrial fibrillation. During postoperative follow-up, adverse outcomes occurred in 8 (12.1%) of 66 patients (1 unplanned admission after surgery, 6 residual TR, and 4 elevated RVSP >50 mmHg on at least 6 months follow-up postoperative transthoracic echocardiography); no death occurred. Two patients had both residual TR and elevation RVSP, and one patient had residual TR and unplanned admission after surgery due to chest pain. Patients with postoperative adverse outcome were significantly older than those without adverse outcomes (74.0±4.1 vs. 60.3±13.3 years, P<0.001). There were no significant intergroup differences in other demographic characteristics.

Echocardiography data and CT analysis results

Patients with postoperative adverse outcome had more frequent severe TR grades, longer TAD_echo, and higher RVSP on echocardiography, compared to those without postoperative adverse outcome (P<0.05, Table 1). Preoperative cardiac CT was performed within 7.5 days (25^th to 75^th percentile, 3.0–21.0 days) from TV surgery; postoperative cardiac CT was performed at 193.8±12.9 days after TV surgery. Postoperative CT in one patient was inadequate to measure RV volume on diastolic phase because of arrhythmia during CT examination. Therefore, postoperative RV volume change could be measured for 65 patients (mean −21.6%±20.1% for RVEDV/BSA; −19.4%±23.3% for RVESV/BSA). In patients with postoperative adverse outcomes, TAD_4ch/BSA on CT was significantly longer than in those without postoperative adverse outcomes (P<0.05, Table 2). RVEDV/BSA, RVESV/BSA, and RVSV/BSA on both preoperative and postoperative CT scans were significantly larger in patients with postoperative adverse outcomes than in those without postoperative adverse outcomes (P<0.05, Table 2). RVEF on preoperative CT was significantly higher in patients with postoperative adverse outcomes (P=0.009). Patients with adverse outcomes had a greater extent of reduction in RV volume (RVEDV/BSA and RVESV/BSA) than those without postoperative adverse outcomes (P<0.05, Table 2).

Prognostic value of cardiac CT-derived parameters

All clinical, echocardiographic, and CT-derived variables satisfied proportional hazard assumption before and after adjustment (Tables S1,S2). In the unadjusted Cox PH model, age, severe TR and longer TAD/BSA on preoperative echocardiography and longer TAD/BSA on preoperative CT, larger RV volume (RVEDV/BSA and RVSV/BSA) on preoperative and postoperative cardiac CT scans, higher RVEF on preoperative CT, and greater volume decrease in RVEDV were significant predictors of postoperative adverse outcomes (Table 3). After adjusting clinical variables (age), severe TR and the longer TAD/BSA on echocardiography, longer TAD_4ch/BSA on preoperative CT, larger RVEDV/BSA and RVSV/BSA on preoperative CT were significant predictors of postoperative adverse outcomes. Greater postoperative RVEDV/BSA change showed a significant association after adjustments.

For classifying groups for survival comparison, optimal cutoff values were calculated for five echocardiographic or CT parameters variables that were significant predictors on adjusted Cox proportional hazard model (Table S3). The best cutoff values for preoperative RVEDV/BSA and postoperative RVEDV decrease were 169.2 mL/m² and −40.5%, respectively.

When restricted mean survival time was compared between groups, patients with longer TAD for both echocardiography and CT showed smaller restricted mean survival time at 1- and 2-year time point, than patient with shorter TAD (Figure 3A), indicating worse event-free survival. Patients with larger RVEDV/BSA and RVSV/BSA on preoperative CT and greater decrease in postoperative RVEDV/BSA showed worse event-free survival at 1- and 2-year timepoints (Figure 3B,3C). Among five parameters, the largest intergroup difference was observed in comparison by preoperative RVSV/BSA (cutoff 37.2 mL/m²) at postoperative 1-year timepoint (difference of 3.0 months, P<0.001) and RVEDV/BSA (cutoff 169.2 mL/m²) at postoperative 2-year timepoint (difference of 8.7 months, P<0.001). In patients with preoperative RVEDV/BSA ≤169.2 mL/m², no event occurred (Figure 3C). In patients with preoperative RVEDV/BSA >169.2 mL/m², there was no significant difference in overall event-free survival in comparison by postoperative RVEDV change, but a small difference in restricted mean survival time was seen at 1-year was noted between groups showing longer restricted mean survival time in patients with RVEDV change >−40.5% (difference of 1.0 month, P<0.001; Figure 3C).

Figure 3 Kaplan-Meier curves show postoperative event-free survival and restricted mean survival time, stratified by echocardiography or CT parameters. Green lines represent patients with TAD or RV volume above the cutoffs and RV volume change below the cutoff, whereas blue lines represent those with TAD or RV volume below the cutoffs and RV volume change above the cutoff. Overall event-free survival and restricted mean survival time at 1- and 2-year time point were significantly shorter (A) in patients with longer preoperative TAD that shorter TAD (left, TAD/BSA on preoperative echocardiography; right, TAD_4ch/BSA on preoperative CT), (B) in patients with larger RV volume on preoperative CT (left, RVEDV/BSA; right, RVSV/BSA), and (C) patients with greater postoperative RV volume decrease (left, postoperative decrease in RVEDV/BSA in the entire study population). (C) In patients with preoperative RVEDV/BSA >169.2 mL/m², there was no significant difference in overall event-free survival in comparison by postoperative RVEDV change, but a small difference in restricted mean survival time was seen at 1-year was noted between groups (right, postoperative decrease in RVEDV/BSA in the subgroup with preoperative RVEDV/BSA >169.2 mL/m²). 4ch, four-chamber; BSA, body surface area; CT, computed tomography; EDV, end-diastolic volume; RMST, restricted mean survival time; RV, right ventricle; RVEDVi, indexed right ventricular end-diastolic volume; RVSVi, indexed right ventricular stroke volume; SV, stroke volume; TAD, tricuspid annulus diameter; TADi, indexed tricuspid annulus diameter.

Parameters associated with postoperative RV volume change

Greater volume reduction of RVEDV/BSA (≤−40.5%) was associated with severe TR, longer TAD/BSA, and higher RVSP on preoperative echocardiography, and longer TAD_4ch/BSA, larger RVEDV/BSA on preoperative CT (Table 4). No clinical variable was associated with greater RVEDV/BSA volume decrease. Comparison of clinical, echocardiographic, and CT parameters according to the RV volume-decrease extent and preoperative RV volume is presented in Table S4. In patients without preoperative RVEDV enlargement (RVEDV/BSA ≤169.2 mL/m²), severe TR on preoperative echocardiography was the only significant predictor of marked postoperative RVEDV/BSA volume reduction [odds ratio (OR) 17.571, P=0.019]. In patients with preoperative RV enlargement, no imaging parameter was associated with the extent of RVEDV/BSA change.

Discussion

This prospective study shows that preoperative and postoperative cardiac CT-based TAD and RV volume parameters can predict postoperative adverse outcomes after TV surgery. Longer TAD and RVEDV/BSA and RVESV/BSA on preoperative cardiac CT are independent predictors of postoperative adverse outcome. Greater extent of postoperative RVEDV/BSA change is associated with small increase in postoperative adverse outcome at 1-year follow-up, in case of enlarged preoperative RV volume.

Assessment of RV systolic function is crucial in preoperative planning in TR patients as impaired RV systolic function negatively impacts functional and survival outcomes following TV surgery (2,17). The prognostic value of preoperative CMR-based RV volume and functional parameters in severe TR for prediction of postoperative outcomes after TV surgery was investigated (18-20). A large preoperative RV volume or low RVEF is an adverse prognostic factor in postoperative death or major adverse cardiac events after TV surgery. Timely surgical correction of severe TR improves functional capacity and clinical outcomes (17), and CMR-based RV volume measurement helps determine the optimal timing for TR surgery (18,19). Despite our endpoint parameter partly differing from those of previous studies (e.g., death or major adverse cardiovascular event), the results showed that large preoperative RV volume on CT was associated with increased postoperative adverse outcomes and can be a determinant for the timing of TV surgery.

Cardiac CT is a useful, accurate modality for evaluating RV volume and function (21); however, the prognostic value of cardiac CT parameters for predicting outcomes after TV surgery was rarely investigated. In a previous study, TAD, tethering angles, and tethering height on preoperative cardiac CT correlated with preoperative TR severity; tethering height was an independent risk factor for recurrent TR (≥ mild) (22). In another study, longer TAD and larger RV volume on preoperative cardiac CT were independent predictors of immediate postoperative RV dysfunction (6). Our study assessed long-term prognostic value of perioperative cardiac CT parameters in TR patients who underwent TV surgery and this has not been previously investigated. Given the low event rate (12.1%), the survival curve with restricted mean survival time, rather than meticulous adjustment for Cox proportional hazard regression analysis, was presented. A longer TAD and larger preoperative volume on preoperative CT showed worse event-free survival at 1- and 2-year timepoints. Preoperative RVEDV/BSA (cutoff 169.2 mL/m²) and RVSV/BSA (cutoff 37.2 mL/m²) discriminated event-free survival with the largest difference among imaging-derived parameters.

A greater post-TV surgery RV volume decrease was associated with increased postoperative adverse outcomes, which was unexpected as successful TR surgery can remarkably reduce RV volumes and preserve RV systolic function (18). The clinical impact of the postoperative RV volume-reduction extent was unclear, partly owing to the lack of follow-up imaging studies with uniform postoperative intervals. Postoperative CMR-indicated RV volume and function changes at 10–52 months in patients operated for severe functional TR showed that RVEDV/BSA, RVESV/BSA, and RVEF decreased [27.2%±26.6%, 19.9%±33.8%, and 5.9%±34.5%, respectively] (18). We showed that on cardiac CT at 6 months after TV surgery, RVEDV/BSA and RVESV/BSA decreased by 21.6%±20.1% and 19.4%±23.3%, respectively. The greater postoperative RV-volume decrease was associated with some preoperative echocardiographic or CT parameters and was an adverse prognostic factor in our cohort. Cautious interpretation of these results is required, given that the parameter is closely associated with the preoperative RV volume. In patients with RVEDV/BSA <169.2 mL/m², no event occurred; thus, the extent of RVEDV/BSA change was not significant. Conversely, in 13 patients with preoperative RVEDV >169.2 mL/m², 5 and 8 patients with smaller and larger RVEDV/BSA decrease, respectively, showed significant but small (1.0 months) difference in restricted mean survival time at 1-year follow-up, but had no significant difference in clinical characteristics, imaging parameters, and long-term outcomes. Therefore, large preoperative RVEDV is an important risk factor for postoperative adverse outcomes, irrespective of the extent of RVEDV change.

Higher RVEF on preoperative CT correlated with increased postoperative adverse outcomes, which was inconsistent with previous CMR-based studies. The difference in volumetric methods (e.g., Simpson’s method vs. 3D-based method, or exclusion vs. inclusion of papillary muscle and trabeculation within endocardial border) between CT and CMR may have affected the results (21). Moreover, RVEF on CT might not entirely reflect RV systolic function in significant TR as the TR regurgitant fraction is not considered.

Our study has several limitations. First, selection bias exists as we prospectively enrolled patients after TV surgery. Postoperative mortality ranged from 6.7% to 25% (19,23,24), but only survivors who could undergo postoperative CT examinations were enrolled; thus, the participants had good general condition and normal renal function. Consequently, the overall event rate of adverse outcomes was not high; especially, hard events, including mortality, did not occur in the participants. Therefore, our study results cannot be generalized for all patients undergoing TV surgery. Nevertheless, this study shows the prognostic value of cardiac CT-derived parameters in survivors of TV surgery. Second, the postoperative RV volumes and volume change in one case were excluded from analysis due to poor image quality caused by arrhythmia. Finally, the potential hazard of radiation exposure by CT and the risk from iodinated contrast agent constitute limitations.

Conclusions

Perioperative assessment of cardiac CT imaging-based TAD and RV volume can provide independent prognostic information for postoperative adverse outcomes in patients undergoing TV surgery. Preoperative RVEDV/BSA is the most useful parameter for predicting postoperative adverse outcomes after TV surgery.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2024-2915/rc

Funding: This study was supported by the DongKook Life Science, Co., Ltd., Korea (No. 4-2018-0725) to Y.J.S.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2024-2915/coif). Y.J.S. reports the funding from DongKook Life Science, Co., Ltd., Korea. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board of Severance Hospital (No. 4-2018-0725), and informed consent was taken from all individual participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Nath J, Foster E, Heidenreich PA. Impact of tricuspid regurgitation on long-term survival. J Am Coll Cardiol 2004;43:405-9. [Crossref] [PubMed]
2. Shiran A, Sagie A. Tricuspid regurgitation in mitral valve disease incidence, prognostic implications, mechanism, and management. J Am Coll Cardiol 2009;53:401-8. [Crossref] [PubMed]
3. Otto CM, Nishimura RA, Bonow RO, Carabello BA, Erwin JP 3rd, Gentile F, Jneid H, Krieger EV, Mack M, McLeod C, O'Gara PT, Rigolin VH, Sundt TM 3rd, Thompson A, Toly C. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation 2021;143:e72-e227. [PubMed]
4. Khalique OK, Cavalcante JL, Shah D, Guta AC, Zhan Y, Piazza N, Muraru D. Multimodality Imaging of the Tricuspid Valve and Right Heart Anatomy. JACC Cardiovasc Imaging 2019;12:516-31. [Crossref] [PubMed]
5. Ahn Y, Koo HJ, Kang JW, Yang DH. Tricuspid Valve Imaging and Right Ventricular Function Analysis Using Cardiac CT and MRI. Korean J Radiol 2021;22:1946-63. [Crossref] [PubMed]
6. Suh YJ, Kim D, Shim CY, Han K, Chang BC, Lee S, Hong GR, Choi BW, Kim YJ. Tricuspid annular diameter and right ventricular volume on preoperative cardiac CT can predict postoperative right ventricular dysfunction in patients who undergo tricuspid valve surgery. Int J Cardiol 2019;288:44-50. [Crossref] [PubMed]
7. Kim JY, Suh YJ, Chang S, Im DJ, Hong YJ, Lee HJ, Hur J, Kim YJ, Choi BW. Feasibility of a single-beat prospective ECG-gated cardiac CT for comprehensive evaluation of aortic valve disease using a 256-detector row wide-volume CT scanner: an initial experience. Int J Cardiovasc Imaging 2018;34:293-300. [Crossref] [PubMed]
8. Suh YJ, Kim YJ, Kim JY, Chang S, Im DJ, Hong YJ. Choi BW. A whole-heart motion-correction algorithm: Effects on CT image quality and diagnostic accuracy of mechanical valve prosthesis abnormalities. J Cardiovasc Comput Tomogr 2017;11:474-81. [Crossref] [PubMed]
9. Sugeng L, Mor-Avi V, Weinert L, Niel J, Ebner C, Steringer-Mascherbauer R, Bartolles R, Baumann R, Schummers G, Lang RM, Nesser HJ. Multimodality comparison of quantitative volumetric analysis of the right ventricle. JACC Cardiovasc Imaging 2010;3:10-8. [Crossref] [PubMed]
10. Goo HW, Park SH. Semiautomatic three-dimensional CT ventricular volumetry in patients with congenital heart disease: agreement between two methods with different user interaction. Int J Cardiovasc Imaging 2015;31:223-32. [Crossref] [PubMed]
11. van Rosendael PJ, Joyce E, Katsanos S, Debonnaire P, Kamperidis V, van der Kley F, Schalij MJ, Bax JJ, Ajmone Marsan N, Delgado V. Tricuspid valve remodelling in functional tricuspid regurgitation: multidetector row computed tomography insights. Eur Heart J Cardiovasc Imaging 2016;17:96-105. [PubMed]
12. Zoghbi WA, Adams D, Bonow RO, Enriquez-Sarano M, Foster E, Grayburn PA, Hahn RT, Han Y, Hung J, Lang RM, Little SH, Shah DJ, Shernan S, Thavendiranathan P, Thomas JD, Weissman NJ. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr 2017;30:303-71. [Crossref] [PubMed]
13. Vahanian A, Beyersdorf F, Praz F, Milojevic M, Baldus S, Bauersachs J, et al. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J 2022;43:561-632. [Crossref] [PubMed]
14. Badano LP, Agricola E, Perez de Isla L, Gianfagna P, Zamorano JL. Evaluation of the tricuspid valve morphology and function by transthoracic real-time three-dimensional echocardiography. Eur J Echocardiogr 2009;10:477-84. [Crossref] [PubMed]
15. Muraru D, Badano LP, Hahn RT, Lang RM, Delgado V, Wunderlich NC, Donal E, Taramasso M, Duncan A, Lurz P, De Potter T, Zamorano Gómez JL, Bax JJ, von Bardeleben RS, Enriquez-Sarano M, Maisano F, Praz F, Sitges M. Atrial secondary tricuspid regurgitation: pathophysiology, definition, diagnosis, and treatment. Eur Heart J 2024;45:895-911. [Crossref] [PubMed]
16. Schoenfeld D. Partial residuals for the proportional hazards regression model. Biometrika 1982;69:239-41. [Crossref]
17. Kim YJ, Kwon DA, Kim HK, Park JS, Hahn S, Kim KH, Kim KB, Sohn DW, Ahn H, Oh BH, Park YB. Determinants of surgical outcome in patients with isolated tricuspid regurgitation. Circulation 2009;120:1672-8. [Crossref] [PubMed]
18. Kim HK, Kim YJ, Park EA, Bae JS, Lee W, Kim KH, Kim KB, Sohn DW, Ahn H, Park JH, Park YB. Assessment of haemodynamic effects of surgical correction for severe functional tricuspid regurgitation: cardiac magnetic resonance imaging study. Eur Heart J 2010;31:1520-8. [Crossref] [PubMed]
19. Park JB, Kim HK, Jung JH, Klem I, Yoon YE, Lee SP, Park EA, Hwang HY, Lee W, Kim KH, Kim YJ, Cho GY, Kim KB, Sohn DW, Ahn H. Prognostic Value of Cardiac MR Imaging for Preoperative Assessment of Patients with Severe Functional Tricuspid Regurgitation. Radiology 2016;280:723-34. [Crossref] [PubMed]
20. Ahn Y, Koo HJ, Kang JW, Choi WJ, Kim DH, Song JM, Kang DH, Song JK, Kim JB, Jung SH, Choo SJ, Chung CH, Lee JW, Yang DH. Prognostic Implication of Right Ventricle Parameters Measured on Preoperative Cardiac MRI in Patients with Functional Tricuspid Regurgitation. Korean J Radiol 2021;22:1253-65. [Crossref] [PubMed]
21. Kim JY, Suh YJ, Han K, Kim YJ, Choi BW. Cardiac CT for Measurement of Right Ventricular Volume and Function in Comparison with Cardiac MRI: A Meta-Analysis. Korean J Radiol 2020;21:450-61. [Crossref] [PubMed]
22. Kabasawa M, Kohno H, Ishizaka T, Ishida K, Funabashi N, Kataoka A, Matsumiya G. Assessment of functional tricuspid regurgitation using 320-detector-row multislice computed tomography: risk factor analysis for recurrent regurgitation after tricuspid annuloplasty. J Thorac Cardiovasc Surg 2014;147:312-20. [Crossref] [PubMed]
23. King RM, Schaff HV, Danielson GK, Gersh BJ, Orszulak TA, Piehler JM, Puga FJ, Pluth JR. Surgery for tricuspid regurgitation late after mitral valve replacement. Circulation 1984;70:I193-7. [PubMed]
24. Staab ME, Nishimura RA, Dearani JA. Isolated tricuspid valve surgery for severe tricuspid regurgitation following prior left heart valve surgery: analysis of outcome in 34 patients. J Heart Valve Dis 1999;8:567-74. [PubMed]