Quantitative Identification of High-Risk Tricuspid Regurgitation by Cardiac Magnetic Resonance

BACKGROUND: The role of cardiac magnetic resonance (CMR) quantification of tricuspid regurgitation (TR) to identify high-risk patients with TR remains poorly defined. The aim of this study was to assess the prognostic relevance of TR quantification and of its consequences by CMR in a large real-world cohort. METHODS: Comprehensive clinical, echocardiographic, and CMR data were collected from patients referred to clinical CMR between 2019 and 2024 and who had TR quantification using tricuspid regurgitant fraction (TRF) and parametric mapping analysis for liver extracellular volume (L-ECV). The primary end point was the composite of all-cause mortality and heart failure hospitalization, both under medical management accounting for the timing of tricuspid intervention for those that received it; the secondary outcome was all-cause mortality. RESULTS: In the 489 patients (median age, 68 years; 41% women) included into this retrospective observational study, median TRF was 21% (interquartile range, 14%-33%). Relative hazard of the composite end point analysis identified TRF thresholds of ≥20% and ≥40% as associated with increased hazard ratios >1 and >2 of the primary outcome, respectively. During a median follow-up of 2.3 years, Kaplan-Meier curves showed that survival free from both outcomes was inversely associated with increasing TRF severity (P<0.001). A TRF≥40% independently predicted both end points after multivariable adjustment. Among 371 with liver mapping data, L-ECV ≥32% was strongly associated with manifestations of right-sided heart failure and with long-term adverse outcomes (all P<0.001), providing incremental prognostic value in survival analysis. Patients with TRF ≥20% and L-ECV ≥32% had the highest rate of adverse events compared with those with TRF ≥20% but L-ECV <32% (P<0.001 for the primary and P=0.012 for the secondary outcome). CONCLUSIONS: In this large cohort, CMR provided several markers of high risk among patients with TR, with TRF thresholds considered by current guidelines as "moderate" TR already associated with worse long-term prognosis. TRF ≥40% was independently associated with both death and heart failure hospitalization. Moreover, L-ECV emerged as a novel imaging biomarker of systemic venous congestion, identifying right heart failure and adding incremental prognostic value to define high-risk patients with TR.