Post-discharge eGFR slope and mortality in acute heart failure with atrial fibrillation

Background The prognostic significance of longitudinal renal function decline remains underexplored in patients with acute heart failure (AHF) and atrial fibrillation (AF), in whom baseline renal dysfunction is common and risk stratification is challenging. Purpose To determine whether the post-discharge trajectory of estimated glomerular filtration rate (eGFR) predicts all-cause and cardiovascular (CV) mortality beyond baseline eGFR, and to explore effect modification by baseline renal function. Methods We retrospectively analysed a multicentre registry of 716 consecutive admissions for AHF with AF (2014–2020). The analysis cohort comprised 347 patients with complete data for the prespecified covariates and ≥2 eGFR points (including baseline) with at least one outpatient measurement between 3 and 24 months after discharge. Annual eGFR slopes (mL/min/1.73 m²/year) were derived from creatinine-based eGFR measurements obtained at approximately 3, 6, 12, and 24 months. All-cause mortality was evaluated using Cox regression. CV mortality was assessed using a Fine–Gray competing-risk model with non-CV death as the competing event. Associations were examined with eGFR slope modelled continuously (per interquartile range and per 5 mL/min/1.73 m²/year decrement) and dichotomously (rapid decline ≤−5 vs non-rapid >−5 mL/min/1.73 m²/year), adjusting for baseline eGFR and clinical covariates. Results Over a median follow-up of 2.0 years, a per-interquartile-range faster eGFR decline (12.3 mL/min/1.73 m²/year) was associated with higher all-cause mortality (HR 1.28, 95% CI 1.14–1.43; p<0.001) and CV mortality (sHR 1.29, 95% CI 1.12–1.48; p<0.001) after multivariable adjustment. Each 5 mL/min/1.73 m²/year more negative slope corresponded to an adjusted HR of 1.10 (95% CI 1.06–1.16) for all-cause death, supporting a graded risk relationship. Patients with rapid eGFR decline had more than three-fold higher risks of all-cause mortality (HR 3.29, 95% CI 1.93–5.62) and CV mortality (sHR 3.53, 95% CI 1.71–7.29) compared with those with non-rapid decline. Three-year survival was 60.8% in the rapid-decline group versus 83.4% in the non-rapid group, and the 3-year cumulative incidence of CV death was 23.6% versus 6.6%. The association between rapid decline and mortality was observed across baseline eGFR strata, with larger relative risks at lower baseline eGFR and a statistically significant interaction with renal function category (p_interaction=0.039), suggesting heightened vulnerability in patients with impaired renal reserve. Conclusion In patients with AHF and AF, the post-discharge eGFR trajectory independently predicts all-cause and CV mortality beyond baseline renal function, with greater impact at lower baseline eGFR. Tracking renal decline may refine risk stratification and help identify high-risk patients who could benefit from closer surveillance and targeted interventions.