R Yan, AT Yan, M Tan, C-M Chow, JS Zaltzman, S Pearce, DH Fitchett, A Langer, SG Goodman, or the Canadian ACS Registry Investigators

BACKGROUND: Previous studies have shown that renal dysfunction is an independent predictor of adverse outcome after myocardial infarction (MI). However, there exist limited data on the relationship between the broad spectrum of renal dysfunction and outcome in unselected patients with acute coronary syndromes (ACS).

METHODS: The Canadian ACS Registry was a prospective observational study of 4627 patients with ACS from 51 centres in 9 provinces. Baseline characteristics, laboratory investigations, cardiac procedures, treatment and outcome in hospital were recorded on standard case report forms. Patients were stratified into quartiles of baseline creatinine clearance (CrCl) calculated according to the Cockcroft-Gault formula. One-year outcome was ascertained by standardized telephone interview.

RESULTS: CrCl was determined for 3531 patients (76.3%), and the cut-points for the quartiles were 54.4, 74.5, and 98.3 ml/min. 1105 patients (31.3%) had renal dysfunction defined as CrCl <60ml/min. Vital status at 1-year was available for 4329 patients (6% lost to follow-up). Advanced age, hypertension, diabetes, previous MI and heart failure were significantly more common across worsening CrCl strata. During index hospitalization, patients with renal dysfunction were less likely to undergo diagnostic cardiac catheterization and percutaneous coronary revascularization (P<0.001), but not coronary bypass surgery. Unadjusted 1-year all-cause mortality rates were 2.6%, 4.2%, 8.2%, 20.7% in the 4 strata of decreasing CrCl, respectively (P<0.001 for trend). In multivariate analysis, CrCl was independently associated with 1-year mortality (odds ratio 1.19 per 10 ml/min decrease in CrCl; 95% CI 1.12 to 1.28; P<0.001), and with 1-year death or MI (odds ratio 1.11; 95% CI 1.06 to 1.17; P<0.001). When creatinine (measured in 98.5% of patients) instead of CrCl was analyzed in the model, the independent association with mortality remained unchanged.

CONCLUSIONS: Renal dysfunction was common among unselected ACS patients, and was associated with other adverse clinical characteristics. After adjustment for other prognosticators, decreased CrCl remained a strong independent predictor of higher overall mortality and risk of death/non-fatal MI at 1-year. Effective management strategies for these high risk patients appear warranted.

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