Opolski, Grzegorz, 1st Chair and Department of Cardiology, Medical University of Warsaw Opolski, Grzegorz, First Department of Cardiology, Warsaw Medical University Opolski, Grzegorz Opolski, Grzegorz, Medical University of Warsaw Opolski, Janusz Kochman i Grzegorz Opolski, Maksymilian P. Opolski, Maksymilian Opolski, Waldemar Karnafel i Grzegorz Oran, Mustafa, Namık Kemal University, Faculty of Medicine Orbach, Ady, Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and the Ruth and Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel Orczyk, Marek Orczykowski, Michał Orczykowski, Michał, National Institute of Cardiology, Arrhythmia Department, Warsaw, Poland (Poland) Orczykowski, Michał Ordak, Michał Ordu, Serkan, Kastamonu Private Anadolu Hospital, Department of Cardiology Orea, Arturo Orea-Tejeda, Arturo Orea-Tejeda, Arturo, Heart Failure Clinic Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, Mexico City, México Orea-Tejeda, Arturo, Heart Failure Clinic, Mexico City, México Orea-Tejeda, Arturo, Heart Failure Clinic, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, Mexico City, Mexico Orea-Tejeda, Arturo Oren, Daniel Orenes-Piñero, Esteban Oręziak, Artur, Institute of Cardiology Warsaw,Poland, Arrhythmia Dept.