Cardiac Strains for Optimization of CRT in Non-Responders

In approximately 30% of patients, cardiac resynchronization therapy (CRT) fails to lead to any improvement of the patients' status. In this study, an investigation of a possible method of optimization through speckle tracking of cardiac strains is attempted. Patients not responding to Cardiac Resynchronization Therapy-Defibrillators (CRT-D) after 3 months are randomly divided into control and intervention groups. Atrioventricular interval is adjusted so that E and A waves do not overlap and the interventricular interval subsequently optimized to yield maximum improvement of the sum of longitudinal+radial+circumferential strains. The left ventricular ejection fraction (LVEF) and NYHA (New York Heart Association Classification improvement 3 months after optimization are evaluated and use of other strain combinations assessed.