Assessment and pathophysiology of microvascular disease: recent progress and clinical implications Stefano Masi1,2†, Damiano Rizzoni 3,4†, Stefano Taddei 1, Robert Jay Widmer 5, Augusto C. Montezano 6, Thomas F. Lüscher7,8, Ernesto L. Schiffrin 9, Rhian M. Touyz 6, Francesco Paneni 8,10,11, Amir Lerman 5, Gaetano A. Lanza 12†, and Agostino Virdis 1*,† 1 Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy; 2 Institute of Cardiovascular Science, University College London, London, UK; 3 Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; 4 Division of Medicine, Istituto Clinico Città di Brescia, Brescia, Italy; 5 Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN, USA; 6 Institute of Cardiovascular & Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK; 7 Heart Division, Royal Brompton and Harefield Hospital and Imperial College, London, UK; 8 Center for Molecular Cardiology, University of Zürich, Zürich, Switzerland; 9 Department of Medicine and Lady Davis Institute, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, QC, Canada; 10 Department of Cardiology, University Heart Center, University Hospital Zurich, Zürich, Switzerland; 11 Department of Research and Education, University Hospital Zurich, Zürich, Switzerland; and 12 Department of Cardiovascular and Thoracic Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy *Corresponding author. Tel: +39 050 992558, Fax: +39 050 992409, Email: [email protected] † Stefano Masi, Damiano Rizzoni, Gaetano A. Lanza and Agostino Virdis contributed equally to the manuscript. The development of novel, non-invasive techniques and standardization of protocols to assess microvascular dysfunction have elucidated the key role of microvascular changes in the evolution of cardiovascular (CV) damage, and their capacity to predict an increased risk of adverse events. These technical advances parallel with the development of novel biological assays that enabled the ex vivo identification of pathways promoting microvascular dysfunction, providing novel potential treatment targets for preventing cerebral-CV disease. In this article, we provide an update of diagnostic testing strategies to detect and characterize microvascular dysfunction and suggestions on how to standardize and maximize the information obtained from each microvascular assay. We examine emerging data highlighting the significance of microvascular dysfunction in the development CV disease manifestations. Finally, we summarize the pathophysiology of microvascular dysfunction emphasizing the role of oxidative stress and its regulation by epigenetic mechanisms, which might represent potential targets for novel interventions beyond conventional approaches, representing a new frontier in CV disease reduction. Take home figure The importance of an integrated approach to microvascular research. The potential contribution of microvascular dysfunction to a specific diseased condition or clinical presentation is suspected and confirmed through central microvascular assessment methods (for example, by estimating the coronary flow reserve by left anterior descending transthoracic echocardiography). Subsequently, non-invasive, reproducible peripheral microvascular assessment techniques might help the identification of potential risk factors associated with microvascular dysfunction in the specific diseased condition. Mechanistic studies can be used to confirm the impact of the putative risk factor and the specific pathways through which it induces microvascular dysfunction. Finally, in situ studies performed on isolated arteries can be used to identify novel potential therapeutic targets. The use of drugs directed against such targets requires clinical validation, closing the circle of the microvascular research framework.