Relation of subclinical serum creatinine elevation to adverse in-hospital outcomes among myocardial infarction patients

Background: Acute kidney injury is associated with adverse outcomes after acute ST elevation myocardial infarction (STEMI). It remains unclear, however, whether subclinical increase in serum creatinine that does not reach the consensus criteria for acute kidney injury is also related to adverse outcomes in STEMI patients undergoing primary percutaneous coronary intervention. Methods: We conducted a retrospective study of 1897 consecutive STEMI patients between January 2008 and May 2016 who underwent primary percutaneous coronary intervention, and in whom acute kidney injury was not diagnosed throughout hospitalization. We investigated the incidence of subclinical acute kidney injury (defined as serum creatinine increase of ≥ 0.1 and < 0.3 mg/dl) and its relation to a composite end point of adverse in hospital outcomes. Results: Subclinical acute kidney injury was detected in 321 patients (17%). Patients with subclinical acute kidney injury had increased rate of the composite end point of adverse in-hospital events (20.3% vs. 9.7%, p<0.001), a finding which was independent of baseline renal function. Individual components of this end point (occurrence of heart failure, atrial fibrillation, need for mechanical ventilation and in-hospital mortality) were all significantly higher among patients with subclinical acute kidney injury (p< 0.05 for all). In a multivariable regression model subclinical acute kidney injury was independently associated with higher risk for adverse in-hospital events (odds ratio 1.92.6, 95% confidence interval: 1.23–2.97, p=0.004). Conclusions: Among STEMI patients treated with primary percutaneous coronary intervention, small, subclinical elevations of serum creatinine, while not fulfilling the consensus criteria for acute kidney injury, may serve as a significant biomarker for adverse outcomes.