Prognostic impact of moderate renal dysfunction in acute coronary syndromes

End-stage renal disease is associated with high cardiovascular mortality. The prognostic importance of milder degrees of renal impairment in patients who have had an acute coronary syndrome (ACS) is less well defined. The purpose of this study was to evaluate the impact of baseline renal dysfunction assessed by estimated glomerular filtration rate (GFR) on mortality in patients admitted with an ACS.

We studied all patients with an ACS consecutively admitted to an Intensive Cardiac Care Unit over 18 months. The GFR was estimated by means of the four-component Modification of Diet in Renal Disease study equation. Patients were grouped according to their estimated GFR (less than 45.0; 45.0 to 59.9; 60.0 to 74.9; and at least 75.0 ml/min/1.73 m2). Primary outcome was death from any cause.

The mean age of the 589 study patients was 64.1 years, 73.7% were male, and 49.2% had an ACS with ST-segment elevation. Arterial hypertension, diabetes mellitus, prior myocardial infarction, and Killip class > I were incrementally more common across increasing renal dysfunction strata (p < 0.01). The use of reperfusion therapy, beta-blockers, and coronary angioplasty was lower in groups with reduced estimated GFR (p < 0.001). Overall six-month mortality was 13.6%. Using the group with an estimated GFR of at least 75.0 ml/min/1.73 m2 as the reference group yielded odds ratios for six-month mortality that increased with the degree of renal impairment. After adjusting for baseline characteristics, impaired renal funtion remained associated with increased mortality. The multivariable-adjusted odds ratio for six-month mortality in patients with mild renal impairment (GFR 60.0 to 74.9 ml/min/1.73 m2) was 2.71 (95% confidence interval [CI] 1.09 to 6.69), compared with 7.53 (95% CI, 3.21 to 17.71) and 8.10 (95% CI, 3.18 to 20.60) in patients with moderate and more severe renal dysfunction, respectively.

Baseline renal dysfunction, as assessed by estimated GFR, is a potent and easily identifiable determinant of outcome after an ACS. Even mild levels of renal impairment are independently associated with increased mortality after an ACS.