Supplementary Material for: Relation of Serum Creatinine Twitches and Outcomes among STEMI Patients

Background: Acute kidney injury (AKI) is notoriously associated with adverse outcomes and mortality in patients with acute coronary syndrome. However, using the general cutoff of 0.3 mg/dL increase from baseline for AKI definition and neglecting smaller changes could result in late diagnosis and impaired prognostication. We aimed to assess the prognostic utility of minor creatinine changes ("twitches") in a large cohort of ST-segment-elevation myocardial infraction (STEMI) patients and determine an optimal cutoff value for future use.

Methods: This retrospective analysis of a prospective database included 2933 consecutive patients admitted with STEMI between 2008-2022 to the cardiac intensive care unit of a large tertiary medical center. Renal function was assessed upon admission and at-least once daily thereafter. Creatinine twitches were defined as a change from baseline to peak creatinine level of between 0.1 to 0.3 mg/dl. 30-day and 1-year mortality were the main outcomes.

Results: From the study cohort (mean age 62 ±13, 19% female, 16% with prior MI), 551 (19%) subjects presented creatinine twitches and 254 (9%) developed AKI. Compared to subjects with stable creatinine, those with creatinine twitches had higher rates of 30-day (1% vs. 2.5%, p<0.001) and 1-year (1.6% vs. 4.4%, p<0.001) mortality. In cox multivariate analysis, creatinine twitches had a higher hazard for 1-year mortality (HR 1.87, 95% CI 1.1-3.2) and only a trend for 30-day mortality (HR 1.52, 95% CI 0.96-2.96). Creatinine rise had an area under the curve of 0.780 (95% CI 0.73-0.83) for 1-year mortality prediction, and 0.12 mg/dl was the optimal cutoff for prediction, with a sensitivity of 71%, specificity of 79%. In sub-group multivariate analysis, only twitches that did not resolve during hospitalization had higher hazard for mortality (HR 3.42, 95% CI 1.65-7.05).

Conclusion: Serum creatinine twitches are common among STEMI patients and correlate with elevated 30 days and 1-year mortality. These seemingly minor changes should prompt renal protective strategies for early detection and treatment.