Impact of contrast-induced acute kidney injury on long-term major adverse cardiovascular events and kidney function after percutaneous coronary intervention: insights from a territory-wide cohort study in Hong Kong

BACKGROUND: The impact of contrast-induced acute kidney injury (CI-AKI) on long-term major adverse cardiovascular events (MACE) remains controversial. METHOD: This was a retrospective cohort study from 14 hospitals under the Hospital Authority of Hong Kong between 2004 and 2017. Severe CI-AKI was defined as an increase in serum creatinine of >50% from the baseline value, an absolute increase of >1 mg/dL (88 μmol/L) or requiring dialysis after percutaneous coronary intervention (PCI). Mild CI-AKI was defined as an increase in serum creatinine of >25% from the baseline value or an absolute increase of >0.5 mg/dL (44 μmol/L) after PCI but not fulfilling the criteria for severe CI-AKI. The primary endpoint was MACE, defined as a composite outcome of all-cause mortality, non-fatal myocardial infarction after hospital discharge, stroke or any unplanned coronary revascularization, in a time-to-first-event analysis up to 5 years after PCI. The secondary endpoints were individual components of MACE and cardiovascular mortality. RESULTS: A total of 34 576 patients were analysed. After adjustment for cardiovascular risk factors, procedural characteristics and medication use, the risk of MACE at 5 years was significantly higher with mild CI-AKI {hazard ratio [HR], 1.18 [95% confidence interval (CI) 1.12–1.26); P < 0.001} and severe CI-AKI [HR 1.92 (95% CI 1.78–2.07); P < 0.001]. Severe CI-AKI was associated with higher adjusted risks of each secondary end point and the risks monotonically accrued over time. CONCLUSIONS: Among patients undergoing a first-ever PCI, CI-AKI of any severity was associated with a higher adjusted risk of MACE at 5 years. Severe CI-AKI has a stronger association with MACE and its individual components, with an excess of early and late events.