Prognostic Implications of RV-Arterial Coupling Estimated by CMR in a Large Cohort of Tricuspid Regurgitation Patients

BACKGROUND: Right ventricular-pulmonary arterial coupling is a known prognostic marker in patients with tricuspid regurgitation (TR). However, its assessment by cardiac magnetic resonance and its clinical implications have not been evaluated. We aimed to assess the prognostic role of a cardiac magnetic resonance surrogate of right ventricular-pulmonary arterial coupling in a large cohort of patients with a spectrum of TR severity. METHODS: Comprehensive data were collected from patients referred for cardiac magnetic resonance from 2019 to 2024 who had TR quantification. Right ventricular-pulmonary arterial coupling was calculated by dividing the forward right ventricular stroke volume (f-RVSV) by the right ventricular end-systolic volume (ESV). The outcome of interest was the composite of all-cause death and heart failure hospitalization, under medical management. RESULTS: In the 631 patients included, median age was 66 (interquartile range [IQR], 54–75) years, median tricuspid regurgitant volume was 18 (IQR, 12–30 mL), median left ventricular ejection fraction was 53 (IQR, 41–61)%, median RV ejection fraction was 53 (IQR, 45–58)%, and median f-RVSV/ESV ratio was 0.82 (IQR, 0.58–1.11). In restricted spline curve analysis, the f-RVSV/ESV ratio cutoff associated with a hazard >1 for the composite outcome was ≤0.57. At baseline, a low f-RVSV/ESV ratio was strongly associated with subjective and objective signs of right heart failure, higher TRI-SCORE, and worse right-sided chamber remodeling (all P <0.001). After a median follow-up of 1.8 years (IQR, 1.5–2.0), patients with a low f-RVSV/ESV ratio showed worse survival ( P <0.001). After comprehensive adjustment for clinical and imaging confounders, f-RVSV/ESV ≤0.57 remained a powerful predictor of outcome (adjusted hazard ratio, 2.36 [95% CI, 1.27–4.37]; P =0.004). Finally, patients with low f-RVSV/ESV displayed a worse long-term prognosis across mild, moderate, and severe TR groups ( P <0.001, P <0.001, and P =0.018, respectively). CONCLUSIONS: In this large cohort of patients with a wide spectrum of TR severity, right ventricular-pulmonary arterial coupling assessed by cardiac magnetic resonance was strongly associated with right-sided heart failure and worse long-term prognosis, even after comprehensive adjustment.