The aim of this study was to evaluate treatment of patients with moderate and severe heart failure (HF) who were resistant to pharmacotherapy in Latvia and to assess the cardiac resynchronisation therapy (CRT) by exploring the predisposing factors which provides CRT efficacy. We accomplished prospective analysis of left ventricle ejection fraction (LVEF) and other parameter changes 12 and 24 months after CRT device implantation, dividing the population into two groups: responders — to whom LVEF improvement was ≥10% and non-responders where ≥ 10% LVEF improvement was not achieved. The study included 50 chronic HF patients with preserved sinus rhythm, who underwent CRT device implantation in Latvia at the Pauls Stradiņš Clinical University Hospital from June 2009 to March 2012. In the group of patients where 12 and 24 months after CRT device implantation LVEF improvement ≥10% was achieved, there were statistically significantly more patients with left bundle branch block (LBBB) QRS morphology, wider QRS complex, nonischemic genesis of HF, and normal systolic blood pressure. Patients with LVEF improvement had more pronounced ventricular dyssynchrony measured by Echo before CRT device implantation and, accordingly, the CRT mode was programmed as left ventricle paced before right ventricle and close to 100% biventricular pacing was achieved and the patient was female.