Association Between Heart Failure Ejection Fraction Phenotypes and Contrast-Associated Acute Kidney Injury: A Systematic Review

Contrast-associated acute kidney injury (CA-AKI) is more common in patients with heart failure (HF). Stratified by left ventricular ejection fraction (LVEF), the effect of disease severity is still unknown. There is little and inconsistent data comparing the risk of CA-AKI among the various forms of HF identified by the latest guidelines of the European Society of Cardiology (ESC). A systematic search of PubMed, Embase, Cochrane Library, and Web of Science (January 1, 2011 - December 11, 2025) for studies reporting CA-AKI outcomes stratified by LVEF phenotypes (heart failure with reduced ejection fraction (HFrEF), heart failure with mildly reduced ejection fraction (HFmrEF), and heart failure with preserved ejection fraction (HFpEF)) was performed. We planned a meta-analysis, but due to heterogeneity in adjusted models and limited study data available, we present a narrative synthesis of adjusted effect estimates. Risk of bias was assessed using Risk Of Bias In Non-randomized Studies - of Exposures (ROBINS-E). Two observational cohort studies comprising 3,499 patients with HF met the eligibility criteria. Both studies reported multivariable-adjusted odds ratios. One study found no significant association between reduced ejection fraction (EF) and CA-AKI after adjustment (HFrEF vs. HFpEF adjusted OR 1.01, 95% CI 0.69-1.74; HFmrEF vs. HFpEF adjusted OR 1.31, 95% CI 0.87-1.96). Another study reported adjusted estimates suggesting higher odds with HFrEF compared with other phenotypes (reported adjusted OR 0.85, 95% CI 0.73-0.98 for phenotype-level comparisons). Because of the differences in study design, populations, and covariate adjustment, we did not pool estimates quantitatively; instead, we describe the findings narratively. Current evidence is limited to two observational cohorts and yields inconsistent adjusted estimates. Therefore, pooled effect estimates weren't reported. The findings suggest that EF alone may not fully reflect kidney vulnerability. Due to the limited number of observational studies, these findings should be interpreted with caution, highlighting the need for larger studies in the future.