According to results of several international clinical trials, Cardiac Resynchronisation Therapy (CRT) among patients with moderately or severely damaged heart's pumping capacity improves quality of life along with reduction of combined morbidity and hospitalisation measures. The procedure involves placing leads in both ventricles and as all complicated heart catheter procedures can be disturbed in many ways. In order to present possible difficulties occurring during the procedure, we investigate one case of ineffective CRT device implantation. We report a patient with permanent ventricular pacing treated in the Department of Electrocardiology, John Paul II Hospital in Krakow, who was admitted with signs of circulatory decompensation and consequently qualified for CRT. Although the patient was remaining in permanently controlled coumarine therapy, the massive thrombosis made the CRT impossible. In this rare condition following procedures are under consideration: implanting the electrode from the left side and connecting it to the right side located pacemaker (unless there is no thrombosis on this side), microthoracotomy with Hunter electrode epicardial placement to restore the proper heart stimulation. This case report highlights the importance of considering potential difficulties occurring during various electrocardiological procedures in patients with impaired pacemaker function.