The Prognostic Impact of Kidney Dysfunction in Unselected Patients Undergoing Coronary Angiography: In What Subgroups Does Kidney Dysfunction Matter?

<b>Background/Objectives</b>: In recent decades, shifting demographics and advancements in treating cardiovascular disease have altered the types of patients receiving coronary angiography (CA). However, data investigating the impact of kidney dysfunction stratified by the indication for CA are limited. <b>Methods</b>: Consecutive patients who underwent invasive CA at one institution between 2016 and 2022 were included in this study. Firstly, the prevalence and extent of coronary artery disease (CAD) in patients with different levels of kidney function was assessed. Secondly, the study examined how impaired kidney function affected long-term outcomes-specifically the risk of rehospitalization for heart failure (HF), acute myocardial infarction (AMI), or the need for coronary revascularization-at 36 months of follow-up. <b>Results</b>: A total of 7624 patients undergoing CA were included with a median estimated glomerular filtration rate (eGFR) of 68.9 mL/min/1.73 m² (IQR: 50.8-84.3). In total, 63.7% of patients had an eGFR ≥ 60 mL/min/1.73 m², 29.0% an eGFR of 30-<60 mL/min/1.73 m², and 7.3% an eGFR of <30 mL/min/1.73 m². Compared to patients with an eGFR ≥ 60 mL/min/1.73 m², those with an eGFR 30-<60 mL/min/1.73 m² and eGFR < 30 mL/min/1.73 m² had a higher prevalence of CAD (66.8% vs. 72.9% and 80.1%, respectively; <i>p</i> = 0.001) and three-vessel CAD (25.6% vs. 34.5% and 39.5%, respectively; <i>p</i> = 0.001). At 36 months of follow-up, patients with an eGFR 30-<60 mL/min/1.73 m² and eGFR < 30 mL/min/1.73 m² suffered from significantly higher risk of HF-associated rehospitalization (HR = 1.937, 95% CI: 1.739-2.157, <i>p</i> = 0.001 and HR = 3.223, 95% CI: 2.743-3.787, <i>p</i> = 0.001, respectively) and AMI compared to patients with an eGFR ≥ 60 mL/min/1.73 m² (reference group). The significantly higher risk of HF-related rehospitalization remained after multivariable adjustment. <b>Conclusions</b>: Both groups with impaired kidney function demonstrated a markedly higher risk of rehospitalization for HF at 36 months-even after multivariate adjustments. Increased risk of HF-related rehospitalization in patients with an eGFR < 30 mL/min/1.73 m² was especially evident if they also presented with decompensated HF and LVEF < 35%. In patients with an eGFR 30-<60 mL/min/1.73 m², presenting with angina pectoris and multivessel disease increased the risk of HF-related rehospitalization.