Predictors and outcome of contrast-induced acute kidney injury in older patients presenting with acute coronary syndrome
Authors: Bugani G , Tonet E , Pavasini R , Serenelli M , Mele D , Caglioni S , Vitali F , Zucchetti O , Verardi F.M , Biscaglia S , Ferrari R , Campo G 
Published: November 2020

Abstract

Background
The number of older patients presenting with acute coronary syndrome (ACS) is increasing. Routine percutaneous coronary intervention (PCI) is performed in order to improve outcome, but comorbidities associated with aging lead to a higher risk of treatment complications. Contrast-induced acute kidney injury (CI-AKI) represents potential harm in older and frail patients, but its impact on long term prognosis is not clear.

Purpose
To evaluate occurrence, predictors, and impact on long term outcome of CI-AKI in elderly patients presenting with ACS.

Methods
A prospective cohort of 392 older (≥70 years) ACS patients who underwent coronary angiography was enrolled. CI-AKI was defined as a serum creatinine increase at least ≥0.3 mg/dl in 48 h or at least ≥50% in 7 days. According to our department protocol, prophylactic hydration was performed to all patients with isotonic saline, given intravenously at a rate of 1 ml/kg body weight/h (0.5 ml/kg for patients with left ventricular ejection fraction &lt;35%) for 12 h before (unless for emergent patients) and 24 h after PCI. Median follow up was 4 [3.0–4.1] years. Long term adverse outcomes include all-cause mortality and any hospitalization for cardiovascular causes (ACS, heart failure, arrhythmia, cerebrovascular accident).

Results
CI-AKI was observed in 72 patients (18.4%). Among patients who developed or not CI-AKI, no difference was found between clinical presentation (Non-ST segment elevation myocardial infarction (NSTEMI) vs. STEMI), left ventricular ejection fraction and multivessel coronary disease. Estimated glomerular filtration rate (odd ratio (OR) 3.59, confidence interval (CI) 1.79–7.20, p&lt;0.001), contrast media volume (OR 1.006, CI 1.002–1.009, P=0.001), white blood cells (OR 1.18, CI 1.10–1.27, p&lt;0.001), haemoglobin level (OR 0.81, CI 0.70–0.94, p=0.005) and chronic obstructive pulmonary disease (OR=5.37, CI 2.24–12.90, p&lt;0.001) were independent predictors for CI-AKI. Patients with CI-AKI presented increased mortality rate both at 30-days (2.7% vs 0%, p=0.038) and at 4-years follow-up (all cause death 23.6 vs. 11.6%, p=0.013) (Figure 1: long term adverse outcomes). Multivariable Cox proportional hazards analysis revealed that diabetes (hazard ratio, HR 1.99, CI 1.33–2.97, p=0.001), atrial fibrillation (HR 2.49, CI 1.59–3.91, p&lt;0.001), Killip class &gt;1 (HR 2.20, CI 1.32–3.67, p=0.003) and haemoglobin level (HR 0.84, CI 0.76–0.92, p&lt;0.001) were independently associated with adverse outcome, while CI-AKI represent a risk factor only at univariate analysis.

Conclusions
CI-AKI is a common complication among older adults undergoing coronary angiography for ACS. Patients who developed CI-AKI had worse outcome at long term follow-up. Actually, the occurrence of CI-AKI was not identified as an independent predictor for long-term adverse outcome, while it may represent a marker of severity of comorbidity and consequent poor prognosis, rather than a causal agent itself.
Figure 1. Kaplan-Maier Curve

Funding Acknowledgement
Type of funding source: None