Opportunistic CT Fatty Muscle Fraction for Outcome Prediction in Patients Undergoing Transcatheter Mitral Valve Edge-to-Edge Repair

BACKGROUND: Frailty is a risk factor for adverse outcomes in patients undergoing mitral valve transcatheter edge-to-edge repair (M-TEER) and is interrelated with sarcopenia. This study aimed to investigate the prognostic value of fatty muscle fraction (FMF), measured from routine preinterventional computed tomography, as an imaging biomarker for frailty in patients undergoing M-TEER. METHODS: In patients undergoing M-TEER between 2010 and 2022 at the Heart Center Bonn who received preprocedural contrast-enhanced computed tomography, skeletal muscle quantity and quality at the L3 vertebral level were assessed on arterial-phase images using a deep learning-based segmentation algorithm. Fatty muscle fraction (FMF) was quantified and correlated with anthropometric, clinical, echocardiographic, and laboratory parameters. The primary end point was all-cause mortality at 1 year following the procedure, with additional follow-up at 30 days, 2 years, and 3 years. RESULTS: A total of 197 patients (median age, 79.3 years [interquartile range, 75.0–84.0]; 54.3% men; median EuroScore II, 4.1 [2.6–5.8]) were investigated. One-year survivors had significantly lower FMF values than nonsurvivors (49.0% [39.0–58.7] versus 57.6% [49.6–69.2]; P <0.001). Patients were divided into tertiles according to the extent of FMF: low FMF (<44.42%), medium FMF (44.42–56.69%), and high FMF (>56.69%). Following M-TEER, high FMF was associated with a higher all-cause mortality at 30 days (16.7% versus 6.1% versus 1.5%; P =0.005), 1 year (30.3% versus 19.7% versus 7.7%; P =0.004), 2 years (36.4% versus 22.7% versus 12.3%; P =0.005) and 3 years (37.9% versus 22.7% versus 13.8%; P =0.005) follow-up. Multivariable Cox regression analysis for 1-year mortality revealed age (hazard ratio, 0.96 [95% CI, 0.93–1.00]; P =0.023), male gender (hazard ratio, 3.65 [95% CI, 1.67–7.975]; P <0.001), and FMF (hazard ratio, 1.05 [95% CI, 1.02–1.08]; P <0.001) as independent predictors of 1-year all-cause mortality. CONCLUSIONS: Computed tomography-derived FMF, as a potentially new frailty marker, is independently associated with all-cause mortality in patients undergoing M-TEER and may serve as a promising parameter for risk stratification.