BACKGROUND: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients suffering from chronic heart failure (CHF). Optimal device programming is crucial for maximum patient benefit. The goal of the present study was to assess device settings from CHF patients undergoing CRT optimization in a "real world" setting, and to delineate parameters most frequently requiring adjustment. METHODS: All patients who underwent CRT device implantation in the Cardiology Clinic at the University Hospital Zurich between January 2011 and September 2012 and in whom follow-up was available were included in this analysis. RESULTS: A total of 170 CHF patients were included in this analysis. True biventricular pacing was present in 44.0% of all patients, while QRS fusion was detected in 49.9%. The majority of the patients presented with suboptimal AV delays requiring adjustment. AV delays were therefore shortened due to the presence of QRS fusion in 53.3% and 38.1% of patients (sAV and pAV, respectively) or prolonged because of truncation of the A wave in the LV inflow pulse wave Doppler measurement (17.5% and 28.4% for sAV and pAV, respectively). In contrast, interventricular delay (VV delay) was rarely changed (11.9%). CONCLUSIONS: In our "real world" cohort, a substantial proportion of patients presented to their first post-operative consultation with suboptimal device settings. Our data indicate that the opportunity to optimize device settings is frequently wasted in the "real world", underlining the necessity for expert device follow-up to deliver optimal care to this challenging group of heart failure patients.