Warfarin treatment, kidney dysfunction and outcome in acute myocardial infarction patients with a history of atrial fibrillation

Abstract

Recent studies suggest that warfarin increases the risk of ischemic stroke and mortality in people with end-stage renal disease and atrial fibrillation (AF). It is unknown at which degree of renal dysfunction the risk outweights the benefit. Cross-sectional study with prospective follow-up in the SWEDEHEART registry. Inclusion criteria were consecutive survivors of MI with history of AF and known serum creatinine (n=24317). Patients were classified into 5 renal disease stages according to their estimated glomerular filtration rate (eGFR). Primary outcome was a composite of death, readmission due to MI, ischemic stroke and bleeding within 1 year. Secondary outcomes were each event separately. Multivariate adjustment included age, sex, comorbidities, presentation, hospital course and discharge medication. A total of 5292 (21,7%) patients received warfarin at discharge. Warfarin treatment was significantly associated with lower risk for both the primary (HR and 95% CI 0.76 [0.72-0.81]) and secondary outcomes (Death, 0.67 [0.61, 0.73]; MI readmission 0.88 [0.81, 0.96]; Ischaemic stroke 0.58 [0.48, 0.71]) without increasing the risk of bleeding (1.04 [0.88, 1.23]). As many as 53,5% of patients had moderate to several renal disease (eGFR<60 ml/min/1.73 m2). For each renal disease strata, warfarin treatment was associated with a decreased risk of overall events as well as of death MI readmission or stroke alone. Bleeding events were neither increased nor reached statistical significance across differing degrees of renal dysfunction. View this table: Table 1. Fully adjusted Cox regression models showing hazards associated with warfarin use in individuals with differing renal function compared to equivalent individuals not receiving warfarin Warfarin treatment associated with a decreased 1-year risk of a composite event of death, readmission for MI, stroke and bleeding in MI patients with a history of AF. This was also true in individuals with mild, moderate and severe renal disease.