Differential impact of metabolic syndrome on arterial stiffness and wave reflections: Focus on distinct definitions Gregory P. Vyssoulis a , Panagiota G. Pietri a, ⁎ , Eva A. Karpanou b , Charalambos V. Vlachopoulos a , Stella-Maria Kyvelou a , Panagiotis Spanos a , Dennis V. Cokkinos b , Christodoulos I. Stefanadis a a Hypertension Unit, 1st Cardiology Department of Athens Medical School, Hippokration Hospital, Athens, Greece b Hypertension Centre, 1st Cardiology Department, Onassis Cardiac Surgery Centre, Athens, Greece Received 6 January 2008; received in revised form 22 June 2008; accepted 8 August 2008 Available online 19 September 2008 Abstract Background: Arterial stiffness and wave reflections are independent predictors of cardiovascular disease. Metabolic syndrome (MS) is related to increased aortic stiffness in several populations. However, it is unclear whether the association of MS with aortic stiffness differs according to the considered definition. Moreover, data regarding the association of wave reflections with MS are limited. For this purpose, we examined the relationship of arterial stiffness and wave reflections with MS by using four current definitions and a score. Methods: We studied 732 never treated, non-diabetic hypertensive patients. Metabolic syndrome was defined by Adult Treatment Panel III, American Heart Association, World Health Organization (WHO), International Diabetes Federation criteria and MS (GISSI) score. Arterial stiffness was assessed by measuring carotid-femoral pulse wave velocity (PWVc-f). Heart rate-corrected augmentation index (AIx 75 ) was estimated as a measure of wave reflections. Results: By all definitions, hypertensive patients with MS had higher PWVc-f compared to hypertensives without MS. On the contrary, no significant difference was observed in AIx 75 between patients with and those without MS except when MS was defined by WHO criteria. An independent association emerged between PWVc-f and GISSI score and MS components (p = 0.038 and 0.033 respectively) in patients with MS, after adjustment for age, gender, LDL cholesterol and smoking. Nevertheless, after further adjustment for systolic blood pressure or body mass index, the strength of this association was reduced to a non-significant level. Conclusion: Arterial stiffness is increased in patients with metabolic syndrome irrespective of the definition criteria. On the contrary, metabolic syndrome has no effect on wave reflections, except when this is defined by WHO criteria. Regarding the high prognostic significance of both arterial stiffness and wave reflections, these findings might have important clinical implications. © 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Metabolic syndrome; Definition criteria; Arterial stiffness; Wave reflections; Hypertension 1. Introduction In the general population, metabolic syndrome (MS) is associated with increased cardiovascular morbidity [1] and mortality [2] and high incidence of diabetes mellitus (DM) type II [3]. Moreover, hypertensive patients with, compared to those without MS exert almost two fold greater cardiovascular risk [4]. Although the prognostic role of MS has been very clearly established, there is still much debate on the definition of the syndrome. Indeed, National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) [5], American Heart Association (AHA, International Journal of Cardiology 138 (2010) 119 – 125 www.elsevier.com/locate/ijcard ⁎ Corresponding author. 1st Cardiology Department, Hippokration Hospital, V. Sofias 114, 11526, Athens, Greece. Tel.: +30 6946103447. E-mail address: panpietri@hotmail.com (P.G. Pietri). 0167-5273/$ - see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2008.08.005