3D Echocardiographic and CMR Imaging for the Assessment of Right Ventricular Function and Tricuspid Regurgitation Severity

BACKGROUND: Tricuspid regurgitation (TR) is associated with increased mortality and is often underdiagnosed due to limitations in imaging modalities. While routine 2-dimensional echocardiography (2DE) demonstrates frequent disagreement with cardiac magnetic resonance imaging (CMR) in classifying TR severity, the incremental value of 3-dimensional echocardiography (3DE) remains unknown also due to the lack of a generalizable grading scheme across imaging modalities. Therefore, this study provides an intermodality comparison of all 3 imaging modalities (2DE, 3DE, and CMR) in evaluating TR severity and proposes an adapted 5-class grading scheme for TR severity using CMR. METHODS: A total of 144 patients with symptomatic TR were analyzed across 2 cohorts: a derivation cohort (n=91) from the University Hospital of Munich and a validation cohort (n=53) from the Heart Center Leipzig. All patients underwent multimodality imaging, including transthoracic 2DE, transesophageal 3DE, and CMR. The adapted 5-class CMR-based grading scheme was proposed and externally validated. RESULTS: In the derivation cohort (median age 81 years, 66% female), TR severity grading by 3DE highly correlated with CMR (87% concordance within a 1-grade difference), significantly outperforming 2DE (68% concordance). While 3DE underestimated RV dimensions compared with CMR ( P <0.001), it provided a comparable measure of TR severity and RV function. 2DE achieved the lowest accuracy rates compared with CMR (34.5%; P =0.005) with frequent overestimation of TR severity. An overestimation of TR severity by 3DE compared with CMR was significantly less frequent than with 2DE (21% versus 56%; P <0.001). Cohen κ analysis confirmed a substantial and superior agreement between 3DE and CMR compared with 2DE (κ=0.63 versus 0.41; P =0.01). The results were externally validated, showing comparable results within the derivation and validation cohorts. CONCLUSIONS: 3DE provides an accurate assessment of TR severity comparable to CMR. The proposed 5-class grading scheme for TR severity using CMR demonstrates high accuracy and external validity.