Acute Kidney Injury Treated with Renal Replacement Therapy and 5-year Mortality After Myocardial Infarction-related Cardiogenic Shock: a Nationwide Population-based Cohort Study

Background: Myocardial infarction-related cardiogenic shock is frequently complicated by acute kidney injury. We examined the influence of acute kidney injury treated with renal replacement therapy (AKI-RRT) on risk of chronic dialysis and mortality, and assessed the role of comorbidity in patients with cardiogenic shock.

Methods: In this Danish cohort study conducted during 2005-2012, we used population-based medical registries to identify patients diagnosed with first-time myocardial infarction-related cardiogenic shock and assessed their AKI-RRT status. We computed the in-hospital mortality risk and adjusted relative risk. For hospital survivors, we computed 5-year cumulative risk of chronic dialysis accounting for competing risk of death. Mortality after discharge was computed with use of Kaplan-Meier methods. We computed 5-year hazard ratios for chronic dialysis and death after discharge, comparing AKI-RRT with non-AKI-RRT patients using a propensity score-adjusted Cox regression model.

Results: We identified 5079 patients with cardiogenic shock, among whom 13% had AKI-RRT. The in-hospital mortality was 62% for AKI-RRT patients, and 36% for non-AKI-RRT patients. AKI-RRT remained associated with increased in-hospital mortality after adjustment for confounders (relative risk=1.70, 95% confidence interval (CI): 1.59-1.81). Among the 3059 hospital survivors, the 5-year risk of chronic dialysis was 11% (95% CI: 8-16%) for AKI-RRT patients, and 1% (95% CI: 0.5-1%) for non-AKI-RRT patients (adjusted hazard ratio: 15.9 (95% CI: 8.7-29.3). The 5-year mortality was 43% (95% CI: 37-53%) for AKI-RRT patients compared with 29% (95% CI: 29-31%) for non-AKI-RRT patients. The adjusted 5-year hazard ratio for death was 1.55 (95% CI: 1.22-1.96) for AKI-RRT patients compared with non-AKI-RRT patients. In patients with comorbidity, absolute mortality increased while relative impact of AKI-RRT on mortality decreased.

Conclusion: AKI-RRT following myocardial infarction-related cardiogenic shock predicted elevated short-term mortality and long-term risk of chronic dialysis and mortality. The impact of AKI-RRT declined with increasing comorbidity suggesting that intensive treatment of AKI-RRT should be accompanied with optimized treatment of comorbidity when possible.