Hepatic Extracellular Volume Fraction by CMR: A Novel Prognostic Marker in Tricuspid Regurgitation

BACKGROUND: Tricuspid regurgitation (TR) leads to systemic venous congestion and congestive hepatopathy, but conventional TR imaging parameters incompletely capture systemic consequences. Hepatic extracellular volume fraction (ECV) on cardiac magnetic resonance T1 mapping may reflect hepatic tissue remodeling and provide prognostic information beyond conventional risk markers. METHODS: Consecutive patients with moderate or greater TR who underwent cardiac magnetic resonance with hepatic T1 mapping were studied. Hepatic ECV was calculated using pre- and postcontrast T1 values and hematocrit. Patients were stratified by hepatic ECV tertiles. The primary end point was all-cause mortality. RESULTS: Among 234 patients (mean age, 65.6±15.8 years; 46.2% men), mean hepatic ECV was 37.7±9.0%, with tertile cutoffs at 32.5% and 41.3%. Higher hepatic ECV tertiles were associated with worse biventricular function and greater TR severity. Right ventricular ejection fraction decreased across tertiles (48.2% versus 48.5% versus 40.3%, P <0.001), while right ventricular end-diastolic volume index increased (107.4 versus 105.4 versus 127.4 mL/m², P <0.001). The prevalence of severe TR (regurgitant fraction ≥50%) increased from 10.9% (mean) across tertiles 1 and 2 to 29.5% in tertile 3 ( P <0.001). During a mean follow-up of 2.2 years, 43 (18.4%) deaths occurred. Mortality increased across hepatic ECV tertiles: 12.8% versus 11.5% versus 30.8% ( P =0.002 for trend). Kaplan-Meier analysis showed 3-year survival rates of 88%, 89%, and 57% across tertiles 1, 2, and 3, respectively. In multivariable Cox regression adjusting for age, right ventricular dysfunction, and severe TR, hepatic ECV tertiles remained independently predictive of mortality (HR, 1.62 [95% CI, 1.06–2.48]; P =0.027). Forward stepwise analysis yielded significant incremental prognostic value beyond traditional TR risk factors, improving model discrimination from χ²=24.4 to 30.1 ( P =0.02). CONCLUSIONS: Hepatic ECV is a novel prognostic marker that provides incremental risk stratification in TR and has potential to impact therapeutic decision-making in the era of expanded treatment options for TR.