SAGE-Hindawi Access to Research International Journal of Hypertension Volume 2011, Article ID 947246, 5 pages doi:10.4061/2011/947246 Review Article Resistant Hypertension and Obstructive Sleep Apnea: The Sparring Partners Costas Thomopoulos,1 Helena Michalopoulou,2 Alexandros Kasiakogias,3 Anna Kefala,3 and Thomas Makris1 1 Department of Cardiology, Elena Venizelou Hospital, 2 Elena Venizelou Sqr., Athens 11521, Greece 2 Department of Cardiology, Metaxa Cancer Hospital, 51 Mpotassi Str., Piraeus 18537, Greece 3 First Cardiology Clinic, University of Athens, Hippokration Hospital, 114 Vas. Soﬁas Str., Athens 11527, Greece Correspondence should be addressed to Costas Thomopoulos, thokos@otenet.gr Received 14 October 2010; Accepted 8 December 2010 Academic Editor: Vasilios Papademetriou Copyright © 2011 Costas Thomopoulos et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Enhanced target organ damage and cardiovascular morbidity represent common issues observed in both resistant hypertension and obstructive sleep apnea. Common pathophysiological features and risk factors justify their coexistence, especially in individuals with increased upper-body adiposity. Impaired sodium handling, sympathetic activation, accelerated arterial stiﬀening, and impaired cardiorenal hemodynamics contribute to drug-resistant hypertension development in obstructive sleep apnea. Eﬀective CPAP therapy qualiﬁes as an eﬀective “add-on” to the underlying antihypertensive pharmacological therapy, and emerging evidence underlines the favorable eﬀect of mineralocorticoid antagonists on both resistant hypertension and obstructive sleep apnea treatment. 1. Introduction In the recent years several original articles and review papers have focused on the association between arterial hypertension and obstructive sleep apnea syndrome (OSA) [1–4]. Such an association is supported by the interplay of common risk factors and pathophysiological pathways aﬀecting both the vascular wall and the upper airway [5]. Regarding risk factors, the obesity epidemic has prompted the recognition of an interaction between OSA and increased blood pressure (BP) [6]; additionally, as the population ages and gains weight, resistant hypertension is becoming more prevalent [7]. Up to date few small epidemiological studies have shown a signiﬁcant association between resistant hypertension and OSA, and based on that both the Seventh Report of the Joint National Committee and the 2007 European Society of Cardiology-European Society of Hypertension guidelines for the management of arterial hypertension recognized OSA as an identiﬁable and not uncommon cause of resistant hyper- tension [8, 9]. Surprisingly, the European guidelines added OSA to the causes of secondary hypertension, thus creating some confusion; indeed, it is yet unresolved whether OSA could represent just a bystander of essential hypertension and whether the gold standard therapeutic approach for OSA, namely, continuous positive airway pressure (CPAP), is accompanied by eﬃcacious treatment of hypertension [4, 5]. Either way, misdiagnosed or inappropriately treated OSA may prevent pharmacological treatment of drug-resistant essential hypertension from reducing BP levels within the goal [10]. In the present paper, we illustrate the pathophysiological and epidemiological evidence that supports the interrela- tionship between resistant hypertension and OSA and how these observations could be translated in clinical decisions in the context of an outpatient hypertension clinic. 2. Pathophysiological Issues 2.1. Obesity. Subjects with increased body size are more likely to suﬀer from hypertension and exhibit diﬃcult- to-control hypertension compared to nonobese controls