Metabolic syndrome and cardiovascular risk prediction in peripheral arterial disease

Background and aims: Metabolic syndrome (MetS) was reported to be associated with increased cardiovascular risk in various settings, however its prognostic impact in peripheral arterial disease (PAD) is scanty. Methods and results: We prospectively studied 173 patients with intermittent claudication and ankle/brachial index (ABI) <0.90, in whom MetS was defined using the criteria of both the revised version of the Adults Treatment Panel III (rATP III) and the International Diabetes Federation (IDF). Of these patients, 52.6% met the rATP III and 54.9% the IDF criteria for MetS. During a median follow-up of 31 months, 54 cardiovascular events occurred. Kaplan-Meier curves showed a greater incidence of ischemic events in patients with MetS than in those without. However, adjusted Cox analyses revealed that only IDF-MetS was independently associated with increased cardiovascular risk (HR = 1.91, 95% CI 1.03-3.51, p = 0.038). Kaplan-Meier curves for the four groups of patients delineated according to the bootstrapped ABI cut-off value (0.73) and the presence or absence of IDF-MetS revealed that the syndrome improved the predictive power of ABI alone. Actually, among patients with an ABI <= 0.73, those with IDF-MetS had a higher cardiovascular risk than those without the syndrome (HR = 2.55, 95% CI 1.22-5.12, p = 0.012). This was confirmed by c-statistic, which was 0.56 for ABI alone and increased to 0.65 (p = 0.046) when IDF-Mets was added to the pressure index. Conclusion: In PAD, IDF-MetS, but not rATF III-MetS, is associated with an increased risk of cardiovascular events. Furthermore, IDF-MetS adds to the prognostic value of ABI, currently the most powerful prognostic indicator in PAD. (C) 2009 Elsevier B.V. All rights reserved.