BACKGROUND: Systemic inflammation is increasingly recognized as an important contributor to cardiovascular outcomes. High-sensitivity CRP (C-reactive protein) is an established biomarker, but its prognostic value after mitral transcatheter edge-to-edge repair remains unclear. Clinical parameters such as body temperature may also reflect systemic inflammation; however, their prognostic role in this setting is uncertain. We sought to investigate the association between baseline inflammation makers and long-term outcomes in patients undergoing mitral transcatheter edge-to-edge repair. METHODS: We analyzed 3511 patients from the OCEAN (Optimized Catheter Valvular Intervention)-Mitral registry with available CRP, categorized by Centers for Disease Control and Prevention/American Heart Association cutoffs: <1.0 mg/L (n=1216), 1.0-3.0 mg/L (n=988), and >3.0 mg/L (n=1307). Body temperature was also assessed as an exploratory inflammatory marker. RESULTS: During a median follow-up of 13 (interquartile range, 10-26) months, 826 deaths and 911 composite event of cardiovascular death or hospitalization for heart failure were observed. In multivariable models, both CRP and body temperature were associated with higher risk of death (CRP: hazard ratio [HR], 1.98 [95% CI, 1.63-2.40]; and body temperature: HR, 1.49 [95% CI, 1.25-1.78]). Patients with both elevated CRP (>3.0 mg/L) and high temperature (≥37.0 °C) had the highest risk. Sequential Cox analyses showed an incremental value of CRP beyond clinical, laboratory, and echocardiographic variables. The prognostic effect was most pronounced in patients without preprocedural inotrope use. CONCLUSIONS: Elevated CRP is an independent and incremental predictor of death and heart failure outcomes after mitral transcatheter edge-to-edge repair, with its prognostic impact amplified by higher body temperature. These findings highlight the importance of incorporating systemic inflammation into risk stratification for structural heart interventions. REGISTRATION: URL: https://www.umin.ac.jp/ctr/; Unique identifier: UMIN-ID: UMIN000023653.