New insight into device therapy for chronic heart failure

Abstract

Even with the remarkable results of cardiac resynchronization therapy (CRT) in the large randomized trials, approximately 30-40% of the patients failed to improve after CRT when the established selection criteria are used, highlighting the need for improvement of the current criteria. In addition, the exact mechanism and effects of CRT on echocardiographic and clinical parameters such as mitral regurgitation, strain and incidence of ventricular arrhythmias are currently unknown. The aim of the current thesis was to further explore these issues using varying non-invasive imaging techniques such as echocardiography, nuclear imaging, magnetic resonance imaging as well as device-based diagnostics. The results of Part I demonstrate that presence of mechanical dyssynchrony within the LV as measured with echocardiography is an important predictor of response after CRT. Also, other factors may influence response such as the presence and location of scar tissue in the LV as well the position of the LV pacing lead. Part II describes the acute and long-term benefit (LV function, strain, mitral regurgitation, myocardial blood flow, oxidative metabolism), prognosis, interruption of CRT and optimization of device settings. In addition, implantable cardioverter-defibrillator (ICD)-backup is preferred in all CRT candidates since 21% experienced appropriate ICD therapy within 2 year after implantation.