Renal dysfunction at admission identifies a more severe clinical phenotype but not worse mid-term outcomes in acute heart failure

Introduction

Renal dysfunction is common in patients hospitalised for acute heart failure (AHF) and has traditionally been associated with adverse prognosis. However, beyond long-term outcomes, impaired renal function at admission may identify a distinct and clinically more severe phenotype. This study aimed to compare baseline characteristics, clinical presentation, and outcomes according to renal function at admission.

Methods

This retrospective observational study included 446 consecutive patients admitted to a heart failure programme between 2019 and 2025. Patients were stratified according to estimated glomerular filtration rate (eGFR) at admission (≥60 vs <60 mL/min/1.73m²). Baseline clinical, laboratory, and echocardiographic variables were analysed. Markers of acute severity and in-hospital mortality were recorded. Follow-up included major adverse cardiovascular events (MACE), defined as cardiovascular death or HF rehospitalisation. Survival analysis was performed using Kaplan–Meier curves and log-rank testing.

Results

Patients with eGFR <60 (n=225) were older (78 [73–83] vs 75 [64–80] years; p<0.001) and had a higher comorbidity burden (Charlson index 7 [5–9] vs 5 [4–6]; p<0.001). Hypertension (85% vs 71%; p<0.001), diabetes (59% vs 42%; p<0.001), dyslipidaemia (65% vs 52%; p=0.003), cerebrovascular disease (23% vs 9%; p<0.001), chronic kidney disease (59% vs 2.3%; p<0.001), and previously diagnosed HF (53% vs 28%; p<0.001) were more frequent. Pre-admission loop diuretic use was significantly higher (59% vs 34%; p<0.001).

Laboratory differences included lower haemoglobin (11.9 [10–13] vs 13.2 [12–14] g/dL; p<0.001) and higher BNP levels at admission (9290 [3553–16796] vs 4896 [1858–5707] pg/mL; p<0.001). LVEF did not differ between groups (45 [30–60] vs 40 [31–60]%; p=0.941).

Renal dysfunction was associated with a more severe acute presentation, including higher rates of acute pulmonary oedema (13% vs 8%; p=0.037), low cardiac output (13% vs 5%; p=0.002), diuretic resistance (16% vs 6%; p<0.001), severe pulmonary hypertension (23% vs 9%; p<0.001), right ventricular dysfunction (33% vs 23%; p=0.016), and in-hospital mortality (3% vs 0.5%; p=0.036).

Despite this more unstable clinical profile, Kaplan–Meier analysis showed no significant differences in mid-term MACE between groups (log-rank p=0.401).

Conclusion

In patients hospitalised for acute heart failure, renal dysfunction at admission, frequently reflecting underlying chronic kidney disease, identified a phenotype characterised by advanced comorbidity, greater haemodynamic instability, and higher in-hospital mortality, without translating into worse mid-term outcomes.Table 1Figure 1