Background: Acute kidney injury (AKI) is a common complication following acute myocardial infarction (AMI) and associated with worse outcomes. Serum Potassium levels (K, mEq/L), which are regulated by the kidneys, are related with poor prognosis in patients with AMI.
Objectiv: To evaluate whether K levels predict imminent AKI in patients with AMI.
Methods: This retrospective nested case-control study was based on medical records of hospitalized AMI patients, 2002-2012. The cases (AKI group) were defined as an increase of ≥1.5-fold in serum creatinine level or a decrease of ≥25% in the estimated glomerular filtration rate (eGFR) during the hospitalization. The control group comprised of matched randomly selected patients that did not develop AKI. For both groups, all creatinine and K levels were obtained for up-to 72 h prior to the AKI diagnosis (index time).
Results: A total of 12,498/17,678 admissions met the inclusion criteria. The AKI and the control groups consisted of 430 and 1345 matched admission respectively. K levels, prior AKI diagnosis seemed to be higher in the AKI group. Multivariate analysis showed that K ≥ 4.5 within 36-56 h prior to the index time was an independent predictor of the subsequent AKI, OR = 2.3, p < .001. The c-statistic of the model was 0.859, p < .001. Predictivity of K for AKI was stronger among ST-elevation (STEMI) vs. Non-ST-elevation AMI (NSTEMI) patients (OR = 4, p < .001 vs. 1.7, p = .025 respectively; p-for-interaction = 0.038).
Conclusions: K ≥ 4.5 is an independent and incremental marker of imminent AKI in patients with AMI, predictivity is stronger in patients with STEMI than NSTEMI.
Keywords: Acute kidney injury; Acute myocardial infarction; Potassium; Prediction.
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