Ankle-brachial Index for the Prognosis of Cardiovascular Disease in Patients with Mild Renal Insufficiency

OBJECTIVE: A low ankle-brachial index (ABI) is a known predictor for future cardiovascular events and mortality in patients with chronic kidney disease (CKD). While most prior studies have defined CKD as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2), recent reports have suggested that the cardiovascular risk may be increased even in early stages of renal insufficiency. We hypothesized that a low ABI may predict future cardiovascular morbidity and mortality in patients with mild impairment of the renal function. METHODS: The IMPACT-ABI study was a retrospective, single-center, cohort study that enrolled and obtained ABI measurements for 3,131 patients hospitalized for cardiovascular disease between January 2005 and December 2012. From this cohort, we identified 1,500 patients with mild renal insufficiency (eGFR =60-89 mL/min/1.73 m(2)), and stratified them into 2 groups: ABI ≤0.9 (low ABI group; 9.2%) and ABI >0.9 (90.8%). The primary outcome measured was the cumulative incidence of major adverse cardiovascular events (MACE; cardiovascular death, myocardial infarction, and stroke). RESULTS: Over a mean follow-up of 5.0 years, 101 MACE occurred. The incidence of MACE was significantly higher in patients with low ABI than in those with ABI >0.9 (30.2% vs. 14.4%, log rank p<0.001). A low ABI was associated with MACE in a univariate Cox proportional hazard analysis. A low ABI remained an independent predictor of MACE in a multivariate analysis adjusted for cardiovascular risk factors (hazard ratio (HR): 2.27; 95% confidence interval (CI): 1.33-3.86; p=0.002). CONCLUSION: Low ABI was an independent predictor for MACE in patients with mild renal insufficiency.