AIMS: To examine: (i) the temporal changes in the management pattern; (ii) the reasons for any treatment disparities; (iii) the relationship between invasive treatment and outcome, among acute coronary syndrome (ACS) patients with vs. without kidney dysfunction.

METHODS AND RESULTS: Canadian ACS I, ACS II registries and Global Registry of Acute Coronary Events (GRACE) were prospective, multi-centre, observational studies of patients with ACS. From 1999 to 2007, non-ST elevation (NSTE) ACS patients were recruited in ACS I (n = 3295; 1999-2001), ACS II (n = 1956; 2002-2003), and GRACE (n = 6491; 2004-2007) in Canada. Using the four-variable Modified Diet in Renal Disease equation, we stratified the study population (n = 11,377) into three groups based on their estimated glomerular filtration rate (eGFR), and examined their treatment and outcome. While in-hospital use of coronary angiography and revascularization increased over time in all groups (P < 0.001), patients with kidney dysfunction were less likely to undergo invasive management (P < 0.001). Unadjusted 1 year mortality was lower among patients receiving in-hospital coronary angiography within all eGFR categories (> or =60 mL/min/1.73 m(2): 2.5 vs. 7.6%, P < 0.001; 30-59 mL/min/1.73 m(2): 8.0 vs. 14.6%, P < 0.001; <30 mL/min/1.73 m(2): 27.5 vs. 41.5%, P = 0.043). In-hospital revascularization was independently associated with lower 1-year mortality (adjusted OR = 0.52, 95% CI 0.36-0.77, P = 0.001), irrespective of eGFR (P for heterogeneity = 0.39). Underestimation of patient risk was the most common barrier to an invasive treatment strategy.

CONCLUSION: Despite temporal increases in invasive management of NSTE-ACS, patients with kidney dysfunction are more commonly treated conservatively, with an associated worse outcome. In-hospital revascularization was independently associated with improved survival, irrespective of eGFR. Randomized controlled trials involving patients with kidney dysfunction are needed to confirm whether more aggressive treatment will improve their poor outcome.