Renal function and outcome in patients with infective endocarditis: Insights from the INFLAME cohort

Background

Infective endocarditis (IE) remains associated with high morbidity and mortality. Impaired renal function is an established risk factor for adverse outcomes in IE. However, longitudinal data on the trajectory of renal function during hospitalization and after discharge are limited.

Purpose

This study aimed to evaluate the impact of baseline renal function and its longitudinal course on clinical outcomes in patients with IE.

Methods

The INFLAME Cohort is a single-centre observational study including both retrospectively and prospectively enrolled patients treated since 2022. All adult patients hospitalized with suspected or confirmed IE were eligible for inclusion and categorized into three subgroups according to estimated glomerular filtration rate (eGFR) at baseline: group 1 with eGFR <30 ml/min, group 2 with eGFR 30-59 ml/min and group 3 with eGFR≥60 ml/min according to KDIGO stages. eGFR was investigated at baseline, at discharge and after 12 months.

Results

After exclusion of patients on hemodialysis, 392 remained for analysis. Hereof, 54 patients were categorized into group 1 (13.8%), 116 into group 2 (29.6%) and 202 in group 3 (51.5%), 20 could not be attributed due to missing values. The median age was 68.0 [58.0, 77.0] years and 28.6% were female. Comorbidities included history of cardiac surgery (41.3%), atrial fibrillation (41.2%), prosthetic valve implantation (35.5%), and COPD (13.3%).

Patients with more severe renal impairment were significantly more often female (44.4% versus 21.8%, p=0.001) and presented with higher rates of cardiomyopathy, more advanced dyspnoea, immunosuppression, implanted cardiac devices and anaemia. Despite undergoing less often surgery for treatment, patients in group 1 stayed longer in hospital and at an intermediate or intensive care unit, received longer catecholamines and more often mechanical ventilation (p<0.001, Table 1). All-cause mortality increased stepwise with declining baseline eGFR (75.5% in group 1, 47.4% in group 2, 25.9% in group 3; p<0.001, Figure 1). In-hospital improvement in renal function was not associated with better survival (p=0.3).

Compared with eGFR at discharge, but not at baseline, eGFR was significantly lower at 12 months (p= 0.01). Higher age, female sex and higher body mass index had a negative correlation with renal function. The presence of positive blood cultures had no impact on the course of renal function, whereas performed surgery showed better eGFR values at all investigated time points.

Conclusion

Baseline renal impairment in IE is associated with increased mortality and greater in-hospital resource utilization. Renal function declined at long-term follow-up, and in-hospital improvement was not associated with better survival. These findings highlight renal dysfunction as a marker of disease severity rather than a modifiable short-term prognostic factor in IE.Table 1Figure 1