Setting up a randomized trial to assess the association of mechanical dyssynchrony (MD) and the success of cardiac resynchronization therapy (CRT) in heart failure with a wide QRS complex is ethically challenging. We therefore investigated this association in a retrospective cohort study observing different treatment strategies which were chosen based on the availability of health care resources. The survival of 500 patients from six Western European centers treated with CRT was compared to their 137 Eastern European counterparts not treated with CRT, with regard to the presence of MD. MD was visually assessed and was defined as the presence of apical rocking and/or septal flash. Patients were followed for a mean of 26 ± 8 months for the occurrence of death of any cause. As compared with medical therapy alone, CRT was associated with a more favorable survival (hazard ratio (HR), 0.53; 95% confidence interval (CI) 0.35-0.79; P = 0.002). Patients with MD treated by CRT had better survival than patients belonging to all other groups-they showed 72%, 66% and 56% reduction in all-cause mortality, respectively, compared to patients with MD not treated by CRT (HR 0.28; 95% CI 0.17-0.44), patients without MD treated by CRT (HR 0.34; 95% CI 0.22-0.52) and patients without MD not treated by CRT (HR 0.44; 95% CI 0.25-0.76). Patients with wide QRS complex who are treated with CRT have a significantly better survival when MD is present.

Cardiovascular Center Aalst OLV Clinic Aalst Belgium

Department of Cardiology Clinical Hospital Centre Zemun Faculty of Medicine University of Belgrade Belgrade Serbia

Department of Cardiology Congenital Heart Diseases and Electrotherapy Medical University of Silesia School of Medicine With the Division of Dentistry Silesian Center for Heart Diseases Zabrze Poland

Department of Cardiology Heart and Diabetes Centre of North Rhine Westphalia Ruhr University Bochum Bad Oeynhausen Germany

Department of Cardiology Institute for Clinical and Experimental Medicine Prague Czech Republic

Department of Cardiology Oslo University Hospital Rikshospitalet Oslo Norway

Department of Cardiovascular Diseases University Hospital Gasthuisberg Catholic University Leuven Herestraat 49 3000 Leuven Belgium

Department of Circulation and Imaging Faculty of Medicine and Health Science NTNU Norwegian University of Science and Technology and Clinic of Cardiology St Olavs Hospital Trondheim Norway

Department of Internal Medicine and Gastroenterology Clinical Emergency Hospital University of Medicine and Pharmacy Carol Davila Bucharest Romania

Klinik für Innere Medizin Und Kardiologie St Vinzenz Hospital Cologne Germany

Practice Steuber and Prinz Clemens August Str 15 49751 Sögel Germany

WSB Academy Dąbrowa Górnicza Poland

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